From what I can find, and what I can calculate, five wires, each ~130
feet long, could make a nice inverted L for 160 meters. One leg for the vertical and horizontal portion of the antenna. Four legs for the counterpoise (ground plane). There are many broken wire antennas stored in my shed which are fodder for the radials. Do all of the legs for the counterpoise need to be 1/4 wavelength or can I substitute some shorter lengths? The feedpoint should somewhere above 50 ohms impedance. As I add more radials that number will reach 50 ohms asymptotically. I can get the vertical part up to 70 or 80 feet above ground with the rest of it horizontal. Most of the radiation should take place from the vertical part since it is closer to the feed point. But there should be some effect from the direction of the horizontal portion. How strongly does the direction of the horizontal portion effect the radiation pattern of the antenna system? My property allows me to point it from 300 degrees around to 200 degrees so I have plenty of options. Between 200 and 300 degrees there is a road used by loggers, and the folks maintaining the towers at the top of this mountain. They can break any antenna lower than 80 feet above ground. Spar poles and cranes clear out any dead limbs across the road. Inquiring minds... Kevin. KD5ONS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Good gracious. Why does everyone overthink 160m? OK, maybe just because it's fun. I get that.
But as to operation, I have one (1) antenna, and it is a 360 foot EDZ (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. No radials needed. Specifically I worked 47 of the 50 states in one 24 hour period on 160m (holdouts were AK, HI and NV - all picked up within a day or two). I could 'splain more, if anyone is interested. 73 Lyn, W0LEN -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of kevinr Sent: Tuesday, August 25, 2020 6:24 PM To: Elecraft Reflector Subject: [Elecraft] Inverted L for 160 meters From what I can find, and what I can calculate, five wires, each ~130 feet long, could make a nice inverted L for 160 meters. One leg for the vertical and horizontal portion of the antenna. Four legs for the counterpoise (ground plane). There are many broken wire antennas stored in my shed which are fodder for the radials. Do all of the legs for the counterpoise need to be 1/4 wavelength or can I substitute some shorter lengths? The feedpoint should somewhere above 50 ohms impedance. As I add more radials that number will reach 50 ohms asymptotically. I can get the vertical part up to 70 or 80 feet above ground with the rest of it horizontal. Most of the radiation should take place from the vertical part since it is closer to the feed point. But there should be some effect from the direction of the horizontal portion. How strongly does the direction of the horizontal portion effect the radiation pattern of the antenna system? My property allows me to point it from 300 degrees around to 200 degrees so I have plenty of options. Between 200 and 300 degrees there is a road used by loggers, and the folks maintaining the towers at the top of this mountain. They can break any antenna lower than 80 feet above ground. Spar poles and cranes clear out any dead limbs across the road. Inquiring minds... Kevin. KD5ONS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Two reasons why I want to use an inverted L. One) it fits my property
well. Two) I have never tried one before. I currently have an extra long doublet. I can't remember the exact length but seem to remember over 120 feet for each leg. The tuner on my K3 just won't match it below 2:1.0 so I don't want to transmit on it. It hears well enough but just won't match. Reason number two pushes me onward :) 73, Kevin. KD5ONS On 8/25/20 4:49 PM, Lyn Norstad wrote: > Good gracious. Why does everyone overthink 160m? OK, maybe just because it's fun. I get that. > > But as to operation, I have one (1) antenna, and it is a 360 foot EDZ (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. No radials needed. > > Specifically I worked 47 of the 50 states in one 24 hour period on 160m (holdouts were AK, HI and NV - all picked up within a day or two). > > I could 'splain more, if anyone is interested. > > 73 > Lyn, W0LEN > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of kevinr > Sent: Tuesday, August 25, 2020 6:24 PM > To: Elecraft Reflector > Subject: [Elecraft] Inverted L for 160 meters > > From what I can find, and what I can calculate, five wires, each ~130 > feet long, could make a nice inverted L for 160 meters. One leg for the > vertical and horizontal portion of the antenna. Four legs for the > counterpoise (ground plane). There are many broken wire antennas stored > in my shed which are fodder for the radials. Do all of the legs for the > counterpoise need to be 1/4 wavelength or can I substitute some shorter > lengths? The feedpoint should somewhere above 50 ohms impedance. As I > add more radials that number will reach 50 ohms asymptotically. > > I can get the vertical part up to 70 or 80 feet above ground with the > rest of it horizontal. Most of the radiation should take place from the > vertical part since it is closer to the feed point. But there should be > some effect from the direction of the horizontal portion. How strongly > does the direction of the horizontal portion effect the radiation > pattern of the antenna system? My property allows me to point it from > 300 degrees around to 200 degrees so I have plenty of options. Between > 200 and 300 degrees there is a road used by loggers, and the folks > maintaining the towers at the top of this mountain. They can break any > antenna lower than 80 feet above ground. Spar poles and cranes clear > out any dead limbs across the road. > > Inquiring minds... > > Kevin. KD5ONS > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by kevinr@coho.net
I use a L for all HF band . One wire going up about 60 feet then goes
horizontal about 85 feet or so. I use a somewhat equal length elevated radial about 10-12 feet off the ground. I use a couple of auto couplers, depending on the radio . A Icom AH-4 for my Icom radios and an SGC 230 for anything else. I don’t run an amp on HF so these work great. I also have a ICE discharge unit to bleed off static to the tuners. This cuts off at 30 MHZ, which is ok as I have separate 6 meter antennas. There are many references to match the antenna and many around here in hilly WV use elevated radials, usually only one to facilitate proper matching. -- Rick Genesis 1-29 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by kevinr@coho.net
**interspersed ...
On 8/25/2020 4:23 PM, kevinr wrote: > From what I can find, and what I can calculate, five wires, each ~130 > feet long, could make a nice inverted L for 160 meters. One leg for > the vertical and horizontal portion of the antenna. Four legs for the > counterpoise (ground plane). There are many broken wire antennas > stored in my shed which are fodder for the radials. Do all of the legs > for the counterpoise need to be 1/4 wavelength or can I substitute > some shorter lengths? **Radial elements on the ground can be of any length, longer [up to a point] is better. Their purpose is to provide a lower loss path than the earth for the return circuit. Elevated radials should be tuned, usually 1/4 wave, to be effective. You can think of them as the "other half" of the vertical radiator, and if you had room and could fold them down, you'd have a center-fed half wave antenna fed at 180 deg. > The feedpoint should somewhere above 50 ohms impedance. As I add > more radials that number will reach 50 ohms asymptotically. **Radiation resistance will be somewhere in the 50 ohm ballpark. Generally, the radiators are not resonant due to physical constraints and there will be some reactance in the feedpoint impedance. That is generally cancelled with a series capacitor [center conductor to radiator] or base inductive loading. > > I can get the vertical part up to 70 or 80 feet above ground with the > rest of it horizontal. Most of the radiation should take place from > the vertical part since it is closer to the feed point. **True. For the most part, the horizontal part acts as a capacity hat. Shipboard antennas for 600 m were often one or more horizontal wires between two masts with a downlead to the transmitter. Most [nearly all] of the radiation came from the downlead. > But there should be some effect from the direction of the horizontal > portion. How strongly does the direction of the horizontal portion > effect the radiation pattern of the antenna system? **It will have a small effect. So will the arrangement of the radials if they are asymmetric in spacing around the radiator or in length. In every case I've seen, the "Fly Poop Axiom"++ applies: Unless you're a broadcast station seeking to maximize field strength at the limits of your effective coverage, the effect is way below the other vagaries of Top Band. > My property allows me to point it from 300 degrees around to 200 > degrees so I have plenty of options. Between 200 and 300 degrees > there is a road used by loggers, and the folks maintaining the towers > at the top of this mountain. They can break any antenna lower than 80 > feet above ground. Spar poles and cranes clear out any dead limbs > across the road. The effect of having one of them take down your antenna will be far, far greater than that produced by precisely aiming the horizontal wire over their territory. Keep it away from the loggers ... with today's equipment, they rarely look up anyway. It's the Fly Poop Axiom vs the Elephant Poop Axiom. [:-) 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County ++Effects and changes so small they are like trying to pick fly poop out of the pepper." You can use your imagination for the elephants [:=) > > > Inquiring minds... > > Kevin. KD5ONS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by kevinr@coho.net
Why not model it? It would be very easy to do using the free version of EZNEC that comes with the ARRL Antenna Book, and you'd be able to try various combinations (like the fact that you could probably get away with just one counterpoise wire like I do) to see the effects. 73, Dave AB7E On 8/25/2020 4:23 PM, kevinr wrote: > From what I can find, and what I can calculate, five wires, each ~130 > feet long, could make a nice inverted L for 160 meters. One leg for > the vertical and horizontal portion of the antenna. Four legs for the > counterpoise (ground plane). There are many broken wire antennas > stored in my shed which are fodder for the radials. Do all of the legs > for the counterpoise need to be 1/4 wavelength or can I substitute > some shorter lengths? The feedpoint should somewhere above 50 ohms > impedance. As I add more radials that number will reach 50 ohms > asymptotically. > > I can get the vertical part up to 70 or 80 feet above ground with the > rest of it horizontal. Most of the radiation should take place from > the vertical part since it is closer to the feed point. But there > should be some effect from the direction of the horizontal portion. > How strongly does the direction of the horizontal portion effect the > radiation pattern of the antenna system? My property allows me to > point it from 300 degrees around to 200 degrees so I have plenty of > options. Between 200 and 300 degrees there is a road used by loggers, > and the folks maintaining the towers at the top of this mountain. > They can break any antenna lower than 80 feet above ground. Spar > poles and cranes clear out any dead limbs across the road. > > Inquiring minds... > > Kevin. KD5ONS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Lyn WØLEN
Pretty sure there are some significant pattern differences between ANY horizontal antenna and a vertical one on 160m ... at least at heights practical for amateur radio purposes. That's probably why. Dave AB7E On 8/25/2020 4:49 PM, Lyn Norstad wrote: > Good gracious. Why does everyone overthink 160m? OK, maybe just because it's fun. I get that. > > But as to operation, I have one (1) antenna, and it is a 360 foot EDZ (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. No radials needed. > > Specifically I worked 47 of the 50 states in one 24 hour period on 160m (holdouts were AK, HI and NV - all picked up within a day or two). > > I could 'splain more, if anyone is interested. > > 73 > Lyn, W0LEN > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of kevinr > Sent: Tuesday, August 25, 2020 6:24 PM > To: Elecraft Reflector > Subject: [Elecraft] Inverted L for 160 meters > > From what I can find, and what I can calculate, five wires, each ~130 > feet long, could make a nice inverted L for 160 meters. One leg for the > vertical and horizontal portion of the antenna. Four legs for the > counterpoise (ground plane). There are many broken wire antennas stored > in my shed which are fodder for the radials. Do all of the legs for the > counterpoise need to be 1/4 wavelength or can I substitute some shorter > lengths? The feedpoint should somewhere above 50 ohms impedance. As I > add more radials that number will reach 50 ohms asymptotically. > > I can get the vertical part up to 70 or 80 feet above ground with the > rest of it horizontal. Most of the radiation should take place from the > vertical part since it is closer to the feed point. But there should be > some effect from the direction of the horizontal portion. How strongly > does the direction of the horizontal portion effect the radiation > pattern of the antenna system? My property allows me to point it from > 300 degrees around to 200 degrees so I have plenty of options. Between > 200 and 300 degrees there is a road used by loggers, and the folks > maintaining the towers at the top of this mountain. They can break any > antenna lower than 80 feet above ground. Spar poles and cranes clear > out any dead limbs across the road. > > Inquiring minds... > > Kevin. KD5ONS > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by kevinr@coho.net
Interesting, I have a doublet 125 feet per leg and fed with 600 ohm true open ladder line (not window line) and the K-3 and KAT-500 both tune it to 1:1 160-6.
Feed point 40 feet up with ends at about 10 feet each. So inverted Vee. Sent from my iPad > On Aug 25, 2020, at 16:59, kevinr <[hidden email]> wrote: > > Two reasons why I want to use an inverted L. One) it fits my property well. Two) I have never tried one before. > > I currently have an extra long doublet. I can't remember the exact length but seem to remember over 120 feet for each leg. The tuner on my K3 just won't match it below 2:1.0 so I don't want to transmit on it. It hears well enough but just won't match. > > Reason number two pushes me onward :) > > 73, Kevin. KD5ONS > > >> On 8/25/20 4:49 PM, Lyn Norstad wrote: >> Good gracious. Why does everyone overthink 160m? OK, maybe just because it's fun. I get that. >> >> But as to operation, I have one (1) antenna, and it is a 360 foot EDZ (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. No radials needed. >> >> Specifically I worked 47 of the 50 states in one 24 hour period on 160m (holdouts were AK, HI and NV - all picked up within a day or two). >> >> I could 'splain more, if anyone is interested. >> >> 73 >> Lyn, W0LEN >> >> >> >> -----Original Message----- >> From: [hidden email] [mailto:[hidden email]] On Behalf Of kevinr >> Sent: Tuesday, August 25, 2020 6:24 PM >> To: Elecraft Reflector >> Subject: [Elecraft] Inverted L for 160 meters >> >> From what I can find, and what I can calculate, five wires, each ~130 >> feet long, could make a nice inverted L for 160 meters. One leg for the >> vertical and horizontal portion of the antenna. Four legs for the >> counterpoise (ground plane). There are many broken wire antennas stored >> in my shed which are fodder for the radials. Do all of the legs for the >> counterpoise need to be 1/4 wavelength or can I substitute some shorter >> lengths? The feedpoint should somewhere above 50 ohms impedance. As I >> add more radials that number will reach 50 ohms asymptotically. >> >> I can get the vertical part up to 70 or 80 feet above ground with the >> rest of it horizontal. Most of the radiation should take place from the >> vertical part since it is closer to the feed point. But there should be >> some effect from the direction of the horizontal portion. How strongly >> does the direction of the horizontal portion effect the radiation >> pattern of the antenna system? My property allows me to point it from >> 300 degrees around to 200 degrees so I have plenty of options. Between >> 200 and 300 degrees there is a road used by loggers, and the folks >> maintaining the towers at the top of this mountain. They can break any >> antenna lower than 80 feet above ground. Spar poles and cranes clear >> out any dead limbs across the road. >> >> Inquiring minds... >> >> Kevin. KD5ONS >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by David Gilbert-2
I am hearing quite a difference between my inverted V and my 1/4 wave
over a ground plane. For the last few weeks I've been hearing less noise on the vertical. Enough less to pull more ops out of the noise. When I try the inverted L I expect there to be a little more noise than the vertical, but less than the doublet. Now to test that hypothesis. Kevin. KD5ONS On 8/25/20 5:04 PM, David Gilbert wrote: > > Pretty sure there are some significant pattern differences between ANY > horizontal antenna and a vertical one on 160m ... at least at heights > practical for amateur radio purposes. > > That's probably why. > > Dave AB7E > > > On 8/25/2020 4:49 PM, Lyn Norstad wrote: >> Good gracious. Why does everyone overthink 160m? OK, maybe just >> because it's fun. I get that. >> >> But as to operation, I have one (1) antenna, and it is a 360 foot EDZ >> (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. No >> radials needed. >> >> Specifically I worked 47 of the 50 states in one 24 hour period on >> 160m (holdouts were AK, HI and NV - all picked up within a day or two). >> >> I could 'splain more, if anyone is interested. >> >> 73 >> Lyn, W0LEN >> >> >> >> -----Original Message----- >> From: [hidden email] >> [mailto:[hidden email]] On Behalf Of kevinr >> Sent: Tuesday, August 25, 2020 6:24 PM >> To: Elecraft Reflector >> Subject: [Elecraft] Inverted L for 160 meters >> >> From what I can find, and what I can calculate, five wires, each ~130 >> feet long, could make a nice inverted L for 160 meters. One leg for the >> vertical and horizontal portion of the antenna. Four legs for the >> counterpoise (ground plane). There are many broken wire antennas stored >> in my shed which are fodder for the radials. Do all of the legs for the >> counterpoise need to be 1/4 wavelength or can I substitute some shorter >> lengths? The feedpoint should somewhere above 50 ohms impedance. As I >> add more radials that number will reach 50 ohms asymptotically. >> >> I can get the vertical part up to 70 or 80 feet above ground with the >> rest of it horizontal. Most of the radiation should take place from the >> vertical part since it is closer to the feed point. But there should be >> some effect from the direction of the horizontal portion. How strongly >> does the direction of the horizontal portion effect the radiation >> pattern of the antenna system? My property allows me to point it from >> 300 degrees around to 200 degrees so I have plenty of options. Between >> 200 and 300 degrees there is a road used by loggers, and the folks >> maintaining the towers at the top of this mountain. They can break any >> antenna lower than 80 feet above ground. Spar poles and cranes clear >> out any dead limbs across the road. >> >> Inquiring minds... >> >> Kevin. KD5ONS >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by kevinr@coho.net
You probably should get acquainted with Rudy Severns, N6LF.
(https://www.antennasbyn6lf.com/) He has written more than you ever want to know about vertical antennas, More specifically to your case, are you planning the radials to be elevated? If so, they need to be the same length, in fact some effort should be made to get all of the currents the same. The last thing you want is a fifty ohm feedpoint impedance with a shortened vertical (which is what an L is). There is evidence that elevated radials are an improvement over on-the-ground or buried radials. Mine are on the ground, mainly because 1) I didn't want to give up radiator height to raise the radials, 2) all of the big guns bury theirs and I don't have room for full length radials anyway in my cactus patch. See my QRZ page for evidence. My modeling shows a little bit of directivity away from the horizontal wire, but it's negligible. Wes N7WS On 8/25/2020 4:23 PM, kevinr wrote: > From what I can find, and what I can calculate, five wires, each ~130 feet > long, could make a nice inverted L for 160 meters. One leg for the vertical > and horizontal portion of the antenna. Four legs for the counterpoise (ground > plane). There are many broken wire antennas stored in my shed which are > fodder for the radials. Do all of the legs for the counterpoise need to be 1/4 > wavelength or can I substitute some shorter lengths? The feedpoint should > somewhere above 50 ohms impedance. As I add more radials that number will > reach 50 ohms asymptotically. > > I can get the vertical part up to 70 or 80 feet above ground with the rest of > it horizontal. Most of the radiation should take place from the vertical part > since it is closer to the feed point. But there should be some effect from > the direction of the horizontal portion. How strongly does the direction of > the horizontal portion effect the radiation pattern of the antenna system? My > property allows me to point it from 300 degrees around to 200 degrees so I > have plenty of options. Between 200 and 300 degrees there is a road used by > loggers, and the folks maintaining the towers at the top of this mountain. > They can break any antenna lower than 80 feet above ground. Spar poles and > cranes clear out any dead limbs across the road. > > Inquiring minds... > > Kevin. KD5ONS > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
I have to be very careful of raised wires on my property. If they are
not above the height of an elk's antlers I am in trouble. I plan to bury them. This is something I've never done before which has its own merit. I have plenty of wire scrap from broken antennas so the non-resonant, buried radials work better for my circumstances. I need to calculate the feed point impedance to see if I need to design a balun for the system to work. Once my main project is done I'll have more time for modeling each method. Thanks for all the ideas guys, 73, Kevin. KD5ONS On 8/25/20 5:23 PM, Wes wrote: > You probably should get acquainted with Rudy Severns, N6LF. > (https://www.antennasbyn6lf.com/) He has written more than you ever > want to know about vertical antennas, > > More specifically to your case, are you planning the radials to be > elevated? If so, they need to be the same length, in fact some effort > should be made to get all of the currents the same. The last thing > you want is a fifty ohm feedpoint impedance with a shortened vertical > (which is what an L is). There is evidence that elevated radials are > an improvement over on-the-ground or buried radials. Mine are on the > ground, mainly because 1) I didn't want to give up radiator height to > raise the radials, 2) all of the big guns bury theirs and I don't have > room for full length radials anyway in my cactus patch. See my QRZ > page for evidence. > > My modeling shows a little bit of directivity away from the horizontal > wire, but it's negligible. > > Wes N7WS > > On 8/25/2020 4:23 PM, kevinr wrote: >> From what I can find, and what I can calculate, five wires, each ~130 >> feet long, could make a nice inverted L for 160 meters. One leg for >> the vertical and horizontal portion of the antenna. Four legs for >> the counterpoise (ground plane). There are many broken wire antennas >> stored in my shed which are fodder for the radials. Do all of the >> legs for the counterpoise need to be 1/4 wavelength or can I >> substitute some shorter lengths? The feedpoint should somewhere >> above 50 ohms impedance. As I add more radials that number will >> reach 50 ohms asymptotically. >> >> I can get the vertical part up to 70 or 80 feet above ground with the >> rest of it horizontal. Most of the radiation should take place from >> the vertical part since it is closer to the feed point. But there >> should be some effect from the direction of the horizontal portion. >> How strongly does the direction of the horizontal portion effect the >> radiation pattern of the antenna system? My property allows me to >> point it from 300 degrees around to 200 degrees so I have plenty of >> options. Between 200 and 300 degrees there is a road used by >> loggers, and the folks maintaining the towers at the top of this >> mountain. They can break any antenna lower than 80 feet above >> ground. Spar poles and cranes clear out any dead limbs across the road. >> >> Inquiring minds... >> >> Kevin. KD5ONS >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Kevin,
Your instincts are right on. But, to answer your question the radials do not need to be 130' long, but it is better than a shorter set. The inverted L represents a 1/4 wave over ground and needs the other half, the radials. But, here is where it gets a little tricky. 5 radials are not enough if they are on the ground, but elevate them and 5 starts to represent a better counterpoise. I have a 132 feet of wire for an inverted L but, I only go vertical for ~61'. I, too, have only 5 radials and they vary in length to fit my backyard; the horizontal section of my antenna goes over the house. The antenna does work well on 160-40 meters, and 1/2 the time I use it on 30 and 1/2 the time I use a 20 meter vertical dipole on 30; it's a pattern thing. And, I have only these two antennas. I do have a suggestion. That is feed your inverted L with a remote antenna tuner. This will allow your antenna to be used on other bands and keep loses low on the transmission line when high SWRs are present, and they will be. How much loss? that will depend on the feed line you use. On 8/25/2020 7:58 PM, kevinr wrote: > Two reasons why I want to use an inverted L. One) it fits my property > well. Two) I have never tried one before. > > I currently have an extra long doublet. I can't remember the exact > length but seem to remember over 120 feet for each leg. The tuner on > my K3 just won't match it below 2:1.0 so I don't want to transmit on > it. It hears well enough but just won't match. > > Reason number two pushes me onward :) > > 73, Kevin. KD5ONS > > > On 8/25/20 4:49 PM, Lyn Norstad wrote: >> Good gracious. Why does everyone overthink 160m? OK, maybe just >> because it's fun. I get that. >> >> But as to operation, I have one (1) antenna, and it is a 360 foot EDZ >> (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. No >> radials needed. >> >> Specifically I worked 47 of the 50 states in one 24 hour period on >> 160m (holdouts were AK, HI and NV - all picked up within a day or two). >> >> I could 'splain more, if anyone is interested. >> >> 73 >> Lyn, W0LEN >> >> >> >> -----Original Message----- >> From: [hidden email] >> [mailto:[hidden email]] On Behalf Of kevinr >> Sent: Tuesday, August 25, 2020 6:24 PM >> To: Elecraft Reflector >> Subject: [Elecraft] Inverted L for 160 meters >> >> From what I can find, and what I can calculate, five wires, each ~130 >> feet long, could make a nice inverted L for 160 meters. One leg for the >> vertical and horizontal portion of the antenna. Four legs for the >> counterpoise (ground plane). There are many broken wire antennas stored >> in my shed which are fodder for the radials. Do all of the legs for the >> counterpoise need to be 1/4 wavelength or can I substitute some shorter >> lengths? The feedpoint should somewhere above 50 ohms impedance. As I >> add more radials that number will reach 50 ohms asymptotically. >> >> I can get the vertical part up to 70 or 80 feet above ground with the >> rest of it horizontal. Most of the radiation should take place from the >> vertical part since it is closer to the feed point. But there should be >> some effect from the direction of the horizontal portion. How strongly >> does the direction of the horizontal portion effect the radiation >> pattern of the antenna system? My property allows me to point it from >> 300 degrees around to 200 degrees so I have plenty of options. Between >> 200 and 300 degrees there is a road used by loggers, and the folks >> maintaining the towers at the top of this mountain. They can break any >> antenna lower than 80 feet above ground. Spar poles and cranes clear >> out any dead limbs across the road. >> >> Inquiring minds... >> >> Kevin. KD5ONS >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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For mine I have 1/4 wave wire for 160, goes up 35-40 ft and over to pole
in corner of the yard with the remainder of the wire. I use mostly random length ground radials on top of the ground, some 1/4 wave, some sorter, some longer, mostly shorter,(someway shorter thanks to the lawn mower height), 12 so far and I add more when I get extra wire. 100 watts I work from here in Maryland to US west coast, Caribbean and into Europe and north Africa. I am happy for now but want to get more vertical height some day. Radials are sections of free 2 each 1000 foot rolls of 4 pair cat 5 cable. Jim/W3FA On 8/25/2020 19:23, kevinr wrote: > From what I can find, and what I can calculate, five wires, each ~130 > feet long, could make a nice inverted L for 160 meters. One leg for > the vertical and horizontal portion of the antenna. Four legs for the > counterpoise (ground plane). There are many broken wire antennas > stored in my shed which are fodder for the radials. Do all of the legs > for the counterpoise need to be 1/4 wavelength or can I substitute > some shorter lengths? The feedpoint should somewhere above 50 ohms > impedance. As I add more radials that number will reach 50 ohms > asymptotically. > > I can get the vertical part up to 70 or 80 feet above ground with the > rest of it horizontal. Most of the radiation should take place from > the vertical part since it is closer to the feed point. But there > should be some effect from the direction of the horizontal portion. > How strongly does the direction of the horizontal portion effect the > radiation pattern of the antenna system? My property allows me to > point it from 300 degrees around to 200 degrees so I have plenty of > options. Between 200 and 300 degrees there is a road used by loggers, > and the folks maintaining the towers at the top of this mountain. > They can break any antenna lower than 80 feet above ground. Spar > poles and cranes clear out any dead limbs across the road. > > Inquiring minds... > > Kevin. KD5ONS > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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KD5ODS is not over thinking anything. He is on the right track, an inverted
L is a much better top band antenna than a low all band horizontal wire. Kevin just needs to model his inverted L, he might be a little surprised to see which way the pattern skews. John KK9A Lyn W0LEN Good gracious. Why does everyone overthink 160m? OK, maybe just because it's fun. I get that. But as to operation, I have one (1) antenna, and it is a 360 foot EDZ (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. No radials needed. Specifically I worked 47 of the 50 states in one 24 hour period on 160m (holdouts were AK, HI and NV - all picked up within a day or two). I could 'splain more, if anyone is interested. 73 Lyn, W0LEN -----Original Message----- From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of kevinr Sent: Tuesday, August 25, 2020 6:24 PM To: Elecraft Reflector Subject: [Elecraft] Inverted L for 160 meters From what I can find, and what I can calculate, five wires, each ~130 feet long, could make a nice inverted L for 160 meters. One leg for the vertical and horizontal portion of the antenna. Four legs for the counterpoise (ground plane). There are many broken wire antennas stored in my shed which are fodder for the radials. Do all of the legs for the counterpoise need to be 1/4 wavelength or can I substitute some shorter lengths? The feedpoint should somewhere above 50 ohms impedance. As I add more radials that number will reach 50 ohms asymptotically. I can get the vertical part up to 70 or 80 feet above ground with the rest of it horizontal. Most of the radiation should take place from the vertical part since it is closer to the feed point. But there should be some effect from the direction of the horizontal portion. How strongly does the direction of the horizontal portion effect the radiation pattern of the antenna system? My property allows me to point it from 300 degrees around to 200 degrees so I have plenty of options. Between 200 and 300 degrees there is a road used by loggers, and the folks maintaining the towers at the top of this mountain. They can break any antenna lower than 80 feet above ground. Spar poles and cranes clear out any dead limbs across the road. Inquiring minds... Kevin. KD5ONS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Kevin,
Be careful when doing these comparisons. A 1/4 wave over a ground plane unless it has a really good radial system may not be as efficient than your inverted L. What I would normally suggest is an A/B test using signal strength at the receiving station, but that has it flaws also, what's the pattern. 73, Barry K3NDM On 8/25/2020 8:21 PM, kevinr wrote: > I am hearing quite a difference between my inverted V and my 1/4 wave > over a ground plane. For the last few weeks I've been hearing less > noise on the vertical. Enough less to pull more ops out of the > noise. When I try the inverted L I expect there to be a little more > noise than the vertical, but less than the doublet. Now to test that > hypothesis. > > Kevin. KD5ONS > > > On 8/25/20 5:04 PM, David Gilbert wrote: >> >> Pretty sure there are some significant pattern differences between >> ANY horizontal antenna and a vertical one on 160m ... at least at >> heights practical for amateur radio purposes. >> >> That's probably why. >> >> Dave AB7E >> >> >> On 8/25/2020 4:49 PM, Lyn Norstad wrote: >>> Good gracious. Why does everyone overthink 160m? OK, maybe just >>> because it's fun. I get that. >>> >>> But as to operation, I have one (1) antenna, and it is a 360 foot >>> EDZ (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. >>> No radials needed. >>> >>> Specifically I worked 47 of the 50 states in one 24 hour period on >>> 160m (holdouts were AK, HI and NV - all picked up within a day or two). >>> >>> I could 'splain more, if anyone is interested. >>> >>> 73 >>> Lyn, W0LEN >>> >>> >>> >>> -----Original Message----- >>> From: [hidden email] >>> [mailto:[hidden email]] On Behalf Of kevinr >>> Sent: Tuesday, August 25, 2020 6:24 PM >>> To: Elecraft Reflector >>> Subject: [Elecraft] Inverted L for 160 meters >>> >>> From what I can find, and what I can calculate, five wires, each ~130 >>> feet long, could make a nice inverted L for 160 meters. One leg for >>> the >>> vertical and horizontal portion of the antenna. Four legs for the >>> counterpoise (ground plane). There are many broken wire antennas >>> stored >>> in my shed which are fodder for the radials. Do all of the legs for the >>> counterpoise need to be 1/4 wavelength or can I substitute some shorter >>> lengths? The feedpoint should somewhere above 50 ohms impedance. As I >>> add more radials that number will reach 50 ohms asymptotically. >>> >>> I can get the vertical part up to 70 or 80 feet above ground with the >>> rest of it horizontal. Most of the radiation should take place from >>> the >>> vertical part since it is closer to the feed point. But there >>> should be >>> some effect from the direction of the horizontal portion. How strongly >>> does the direction of the horizontal portion effect the radiation >>> pattern of the antenna system? My property allows me to point it from >>> 300 degrees around to 200 degrees so I have plenty of options. Between >>> 200 and 300 degrees there is a road used by loggers, and the folks >>> maintaining the towers at the top of this mountain. They can break any >>> antenna lower than 80 feet above ground. Spar poles and cranes clear >>> out any dead limbs across the road. >>> >>> Inquiring minds... >>> >>> Kevin. KD5ONS >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [hidden email] >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [hidden email] >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
So Michael — what do you use for a baking between the open wire feeder and
the coaxial outputs of the KPA500? Go go with noises of a vertical antenna, a separate quiet receiving antenna like a K9AY is helpful. Important is to have fun. On Tue, Aug 25, 2020 at 20:31 Barry LaZar <[hidden email]> wrote: > Kevin, > > > > Be careful when doing these comparisons. A 1/4 wave over a ground > > plane unless it has a really good radial system may not be as efficient > > than your inverted L. What I would normally suggest is an A/B test using > > signal strength at the receiving station, but that has it flaws also, > > what's the pattern. > > > > 73, > > > > Barry > > > > K3NDM > > > > On 8/25/2020 8:21 PM, kevinr wrote: > > > I am hearing quite a difference between my inverted V and my 1/4 wave > > > over a ground plane. For the last few weeks I've been hearing less > > > noise on the vertical. Enough less to pull more ops out of the > > > noise. When I try the inverted L I expect there to be a little more > > > noise than the vertical, but less than the doublet. Now to test that > > > hypothesis. > > > > > > Kevin. KD5ONS > > > > > > > > > On 8/25/20 5:04 PM, David Gilbert wrote: > > >> > > >> Pretty sure there are some significant pattern differences between > > >> ANY horizontal antenna and a vertical one on 160m ... at least at > > >> heights practical for amateur radio purposes. > > >> > > >> That's probably why. > > >> > > >> Dave AB7E > > >> > > >> > > >> On 8/25/2020 4:49 PM, Lyn Norstad wrote: > > >>> Good gracious. Why does everyone overthink 160m? OK, maybe just > > >>> because it's fun. I get that. > > >>> > > >>> But as to operation, I have one (1) antenna, and it is a 360 foot > > >>> EDZ (dipole) cut for 3.5 MHz. It's great on all bands, 160 - 6m. > > >>> No radials needed. > > >>> > > >>> Specifically I worked 47 of the 50 states in one 24 hour period on > > >>> 160m (holdouts were AK, HI and NV - all picked up within a day or two). > > >>> > > >>> I could 'splain more, if anyone is interested. > > >>> > > >>> 73 > > >>> Lyn, W0LEN > > >>> > > >>> > > >>> > > >>> -----Original Message----- > > >>> From: [hidden email] > > >>> [mailto:[hidden email]] On Behalf Of kevinr > > >>> Sent: Tuesday, August 25, 2020 6:24 PM > > >>> To: Elecraft Reflector > > >>> Subject: [Elecraft] Inverted L for 160 meters > > >>> > > >>> From what I can find, and what I can calculate, five wires, each ~130 > > >>> feet long, could make a nice inverted L for 160 meters. One leg for > > >>> the > > >>> vertical and horizontal portion of the antenna. Four legs for the > > >>> counterpoise (ground plane). There are many broken wire antennas > > >>> stored > > >>> in my shed which are fodder for the radials. Do all of the legs for the > > >>> counterpoise need to be 1/4 wavelength or can I substitute some shorter > > >>> lengths? The feedpoint should somewhere above 50 ohms impedance. As I > > >>> add more radials that number will reach 50 ohms asymptotically. > > >>> > > >>> I can get the vertical part up to 70 or 80 feet above ground with the > > >>> rest of it horizontal. Most of the radiation should take place from > > >>> the > > >>> vertical part since it is closer to the feed point. But there > > >>> should be > > >>> some effect from the direction of the horizontal portion. How strongly > > >>> does the direction of the horizontal portion effect the radiation > > >>> pattern of the antenna system? My property allows me to point it from > > >>> 300 degrees around to 200 degrees so I have plenty of options. Between > > >>> 200 and 300 degrees there is a road used by loggers, and the folks > > >>> maintaining the towers at the top of this mountain. They can break any > > >>> antenna lower than 80 feet above ground. Spar poles and cranes clear > > >>> out any dead limbs across the road. > > >>> > > >>> Inquiring minds... > > >>> > > >>> Kevin. KD5ONS > > >>> > > >>> ______________________________________________________________ > > >>> Elecraft mailing list > > >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft > > >>> Help: http://mailman.qth.net/mmfaq.htm > > >>> Post: mailto:[hidden email] > > >>> > > >>> This list hosted by: http://www.qsl.net > > >>> Please help support this email list: http://www.qsl.net/donate.html > > >>> Message delivered to [hidden email] > > >>> > > >>> ______________________________________________________________ > > >>> Elecraft mailing list > > >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft > > >>> Help: http://mailman.qth.net/mmfaq.htm > > >>> Post: mailto:[hidden email] > > >>> > > >>> This list hosted by: http://www.qsl.net > > >>> Please help support this email list: http://www.qsl.net/donate.html > > >>> Message delivered to [hidden email] > > >> > > >> ______________________________________________________________ > > >> Elecraft mailing list > > >> Home: http://mailman.qth.net/mailman/listinfo/elecraft > > >> Help: http://mailman.qth.net/mmfaq.htm > > >> Post: mailto:[hidden email] > > >> > > >> This list hosted by: http://www.qsl.net > > >> Please help support this email list: http://www.qsl.net/donate.html > > >> Message delivered to [hidden email] > > > ______________________________________________________________ > > > Elecraft mailing list > > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > > Help: http://mailman.qth.net/mmfaq.htm > > > Post: mailto:[hidden email] > > > > > > This list hosted by: http://www.qsl.net > > > Please help support this email list: http://www.qsl.net/donate.html > > > Message delivered to [hidden email] > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:[hidden email] > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to [hidden email] -- 73 de Ted Edwards, W3TB and GØPWW and thinking about operating CW: "Do today what others won't, so you can do tomorrow what others can't." ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by kevinr@coho.net
If you are going to go with buried radials, I don't think 4 or 5 of them is going to do a very good job for you. Like N7WS recommended, look up N6LF's work and read it carefully. Seriously. 73, Dave AB7E On 8/25/2020 5:31 PM, kevinr wrote: > I have to be very careful of raised wires on my property. If they are > not above the height of an elk's antlers I am in trouble. I plan to > bury them. This is something I've never done before which has its own > merit. I have plenty of wire scrap from broken antennas so the > non-resonant, buried radials work better for my circumstances. I need > to calculate the feed point impedance to see if I need to design a > balun for the system to work. Once my main project is done I'll have > more time for modeling each method. > > Thanks for all the ideas guys, > > 73, Kevin. KD5ONS > > > On 8/25/20 5:23 PM, Wes wrote: >> You probably should get acquainted with Rudy Severns, N6LF. >> (https://www.antennasbyn6lf.com/) He has written more than you ever >> want to know about vertical antennas, >> >> More specifically to your case, are you planning the radials to be >> elevated? If so, they need to be the same length, in fact some >> effort should be made to get all of the currents the same. The last >> thing you want is a fifty ohm feedpoint impedance with a shortened >> vertical (which is what an L is). There is evidence that elevated >> radials are an improvement over on-the-ground or buried radials. >> Mine are on the ground, mainly because 1) I didn't want to give up >> radiator height to raise the radials, 2) all of the big guns bury >> theirs and I don't have room for full length radials anyway in my >> cactus patch. See my QRZ page for evidence. >> >> My modeling shows a little bit of directivity away from the >> horizontal wire, but it's negligible. >> >> Wes N7WS >> >> On 8/25/2020 4:23 PM, kevinr wrote: >>> From what I can find, and what I can calculate, five wires, each >>> ~130 feet long, could make a nice inverted L for 160 meters. One >>> leg for the vertical and horizontal portion of the antenna. Four >>> legs for the counterpoise (ground plane). There are many broken >>> wire antennas stored in my shed which are fodder for the radials. Do >>> all of the legs for the counterpoise need to be 1/4 wavelength or >>> can I substitute some shorter lengths? The feedpoint should >>> somewhere above 50 ohms impedance. As I add more radials that >>> number will reach 50 ohms asymptotically. >>> >>> I can get the vertical part up to 70 or 80 feet above ground with >>> the rest of it horizontal. Most of the radiation should take place >>> from the vertical part since it is closer to the feed point. But >>> there should be some effect from the direction of the horizontal >>> portion. How strongly does the direction of the horizontal portion >>> effect the radiation pattern of the antenna system? My property >>> allows me to point it from 300 degrees around to 200 degrees so I >>> have plenty of options. Between 200 and 300 degrees there is a road >>> used by loggers, and the folks maintaining the towers at the top of >>> this mountain. They can break any antenna lower than 80 feet above >>> ground. Spar poles and cranes clear out any dead limbs across the >>> road. >>> >>> Inquiring minds... >>> >>> Kevin. KD5ONS >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [hidden email] >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by Barry LaZar
FWIW, I use WSPR to compare antennas. That usually gives me a
comparison list of more than a dozen receive stations. I do multiple transmissions and then compare the differences. There may be propagation changes during the different transmission periods but a couple of repeats seems to average that out. It not only provides data in different directions but also different distances. To get a same time comparison, I have used dual transmitters on slightly different frequencies but that gets complicated. Ken WA8JXM On 8/25/2020 9:28 PM, Barry LaZar wrote: > > Be careful when doing these comparisons. A 1/4 wave over a ground > plane unless it has a really good radial system may not be as > efficient than your inverted L. What I would normally suggest is an > A/B test using signal strength at the receiving station, but that has > it flaws also, what's the pattern. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by kevinr@coho.net
Kevinr,
I have an inverted-L on 630m (that is 475 KHz) and is simply a vertical section with one horizontal section. A quarter wave vertical for 1.8 MHz would be 137-foot high so 80 foot is going to be short. The horizontal wires add capacitance to the top end of the vertical effectively shortening the length needed for resonance. My inv-L is only 43-foot high (1/4WL= 524-feet) so its not very efficient and requires a big loading coil in series to resonate. If you have four top-hat wires that may work better to shorten the needed vertical. But probably still need a loading coil. Use EZNEC to model it and it will provide a close est of the antenna Z. I modified my MFJ-269B to operate 400-800 KHz and directly measured mine; adjusted coil to reach resonance. Also do not forget it also needs ground radials (more the merrier)! I only had a 100-foot square patch of ground for my inv-L so radials are very short as well. But my signal has been heard 4,000 miles away with 4w EIRP (100w output from amp). Antenna is currently down. 73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
In reply to this post by kevinr@coho.net
Kevin,
My advice is to get Moxon's book, "Wire Antennas for All Locations." Follow his advice, which is (roughly): use four elevated radials at a level higher than an Elk's antlers. Make the radials equal in length, about 0.15 wavelength long, connect them together, and add an inductance in this common ground lead to resonate them. This helps equalize the currents in the radials, which keeps your radiation angle low. Do not use buried radials unless you have room for at least 16 of them. In that case they can also be about 0.15 wl long. 73, Victor, 4X6GP Rehovot, Israel Formerly K2VCO CWops no. 5 http://www.qsl.net/k2vco/ On 26/08/2020 3:31, kevinr wrote: > I have to be very careful of raised wires on my property. If they are > not above the height of an elk's antlers I am in trouble. I plan to > bury them. This is something I've never done before which has its own > merit. I have plenty of wire scrap from broken antennas so the > non-resonant, buried radials work better for my circumstances. I need > to calculate the feed point impedance to see if I need to design a balun > for the system to work. Once my main project is done I'll have more > time for modeling each method. > > Thanks for all the ideas guys, > > 73, Kevin. KD5ONS > > > On 8/25/20 5:23 PM, Wes wrote: >> You probably should get acquainted with Rudy Severns, N6LF. >> (https://www.antennasbyn6lf.com/) He has written more than you ever >> want to know about vertical antennas, >> >> More specifically to your case, are you planning the radials to be >> elevated? If so, they need to be the same length, in fact some effort >> should be made to get all of the currents the same. The last thing >> you want is a fifty ohm feedpoint impedance with a shortened vertical >> (which is what an L is). There is evidence that elevated radials are >> an improvement over on-the-ground or buried radials. Mine are on the >> ground, mainly because 1) I didn't want to give up radiator height to >> raise the radials, 2) all of the big guns bury theirs and I don't have >> room for full length radials anyway in my cactus patch. See my QRZ >> page for evidence. >> >> My modeling shows a little bit of directivity away from the horizontal >> wire, but it's negligible. >> >> Wes N7WS >> >> On 8/25/2020 4:23 PM, kevinr wrote: >>> From what I can find, and what I can calculate, five wires, each ~130 >>> feet long, could make a nice inverted L for 160 meters. One leg for >>> the vertical and horizontal portion of the antenna. Four legs for >>> the counterpoise (ground plane). There are many broken wire antennas >>> stored in my shed which are fodder for the radials. Do all of the >>> legs for the counterpoise need to be 1/4 wavelength or can I >>> substitute some shorter lengths? The feedpoint should somewhere >>> above 50 ohms impedance. As I add more radials that number will >>> reach 50 ohms asymptotically. >>> >>> I can get the vertical part up to 70 or 80 feet above ground with the >>> rest of it horizontal. Most of the radiation should take place from >>> the vertical part since it is closer to the feed point. But there >>> should be some effect from the direction of the horizontal portion. >>> How strongly does the direction of the horizontal portion effect the >>> radiation pattern of the antenna system? My property allows me to >>> point it from 300 degrees around to 200 degrees so I have plenty of >>> options. Between 200 and 300 degrees there is a road used by >>> loggers, and the folks maintaining the towers at the top of this >>> mountain. They can break any antenna lower than 80 feet above >>> ground. Spar poles and cranes clear out any dead limbs across the road. >>> >>> Inquiring minds... >>> >>> Kevin. KD5ONS Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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