antenna farm
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Fellow Elecrafters,
I have a feeling this may open the flood gates but here goes. I am a newbie Ham but a long time SWL going back to my Knight Kit Star Roamer. I am fixin' to set-up my antenna farm. OK, it will be more like an antenna garden as I have a small house and lot. My K3/100 has a KAT3 and KRX3. I plan on using 3 Dipoles and maybe an inverted V for diversity receive (what a great feature). I got on Google Earth and plotted out the areas I am interested in. I live just up the street from Elecrafts new HQ (talk about fast service) on the central coast of California (CM96CX). A bearing of 118 deg (antenna runs from 28 to 208 deg) cuts across Central America and South America on one side and across Manila and Singapore, skirting Japan, on the other (298 deg). This is a great coverage for me as I used to live in Singapore and spent lots of time in Asia (work) and Central America (not work). The next one is 32 deg (antenna runs from 122 to 302 deg) which cuts through London and Rome on to the Middle East. The other side is not too much, Tahiti and the South Pacific. I am thinking of a reflector on this one as there is not allot at 212 deg that interests me and that should help with Europe, I think. The next one is 78 deg (antenna runs from 122 to 302 deg) which cuts across the US through North Carolina, Bermuda and on to South Africa. The other side, 258 deg, runs through the Solomon Islands and right down the middle of Australia to Perth. I know the lobes will spread way out from these bearings over these long distances but these numbers are a starting point. The antennas will also cross forming a pattern similar to an asterisk on my roof/lot, a good thing I am guessing. I was thinking about Inverted V's for most of these until I checked what the side lobes would pick-up. On the 118 deg antenna it would be the South Pacific (no problem) and Europe (big interference problem while shooting for C/S America and SE Asia). The 32 deg would pick-up Japan, SE Asia on one side lobe and Mexico, Central America on the other. Too many unwanted signals if I am trying for Europe. The 78 deg side lobes would pick-up Alaska, central Russia and west India on one side and the South Pacific, places like Pitcairn, and on to Antarctica. Maybe an inverted V would be OK on this one. The Diversity may be a big inverted V or just an L shape long wire. I laid out a spread sheet with the lengths for a Dipole plus 15 deg, 22 deg, 30 deg, 37 deg, 45 deg, 60 deg and 75 deg inverted V's from 160 to 2 meters using the center of the Extra class bands (my next conquest) looking for some magic number. Nothing jumps out at me but of course a ¼ wave 80 is close to a ½ wave 40, a ½ 60, ¼ 30 and so on. I think I can squeeze in a ¼ wave 80 meter dipole (~31.2 feet/side) in most directions and maybe a shorter one above this (easiest for me but technically wrong?). The longer one higher may be possible but won't be easy. 160 meters will be another project for another day. So my questions are: 1) What length would be best and give me the use of the most bands? Remember, I have a limited space. 2) How far from the dipole should a reflector be. It should be about 5% longer and grounded, right? 3) The auto-tuner on the K3 is amazing. Is it easier for it to tune an antenna that is to long or to short? I'm guessing long but I am not certain. 4) Any suggestions on which band/antenna length is best for these targets? I am mostly active late afternoon and evening (till about 10 PST) and mornings after 6. Thanks, Clint KI6SSN __________ Information from ESET NOD32 Antivirus, version of virus signature database 4687 (20091214) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ______________________________________________________________ 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 |
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Hi Clint!
Welcome to the reflector.... The reality is that most won't be able to place antennas high enough and free of surroundings to realize their "text book" or free space patterns, and it's more a case of "you takes what you gets". It's a complicated matter, with many variables, all mostly beyond our control. 73! Ken Kopp - K0PP [hidden email] http://tinyurl.com/7lm3m5 ______________________________________________________________ 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 |
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In reply to this post by Clint-2
In a space limited situation, a parallel dipole (or inverted-V) does
well. Just calculate your 1/2 wave lengths for each band connect them to a common feedpoint. Use small diameter PVC for spreaders. Even on a small lot, you could get away with an 80-10 parallel (fan) inverted-V. The ends of the 80m elements can be bent towards the ground, sideways, etc. Trimming each band's elements can be tedious, but you could just live with the cut-by-formula mismatch and use the tuner, you'll be in the general ballpark. As far as position/bearing, unless you are erecting nearly flat-top dipoles and at decent heights (ie. 60ft on 40M), you're not going to see any significant directivity or pronounced broadside pattern. An inverted-V approaches a more omni-directional pattern and low heights produce higher angle (ie. cloud burner) radiation. Add in objects around the antenna and all kinds of weird things start to happen (ie rain gutters, metal roof ridges, etc.) Check this out for relative patterns vs. height, referenced to 40M: http://www.qsl.net/aa3rl/ant2.html Reflectors/directors can be added to an inverted-V setup, and do work well for directivity, but again, the resulting radiation angles will depend on height. For diversity on a small lot, I would try a loop or a vertical to compliment the dipole(s)/inverted-V. GL es 73 - no3m Clint wrote: > Fellow Elecrafters, > > I have a feeling this may open the flood gates but here goes. > > I am a newbie Ham but a long time SWL going back to my Knight Kit Star Roamer. I am fixin' to set-up my antenna farm. OK, it will be more like an antenna garden as I have a small house and lot. My K3/100 has a KAT3 and KRX3. I plan on using 3 Dipoles and maybe an inverted V for diversity receive (what a great feature). I got on Google Earth and plotted out the areas I am interested in. I live just up the street from Elecrafts new HQ (talk about fast service) on the central coast of California (CM96CX). > > A bearing of 118 deg (antenna runs from 28 to 208 deg) cuts across Central America and South America on one side and across Manila and Singapore, skirting Japan, on the other (298 deg). This is a great coverage for me as I used to live in Singapore and spent lots of time in Asia (work) and Central America (not work). > > The next one is 32 deg (antenna runs from 122 to 302 deg) which cuts through London and Rome on to the Middle East. The other side is not too much, Tahiti and the South Pacific. I am thinking of a reflector on this one as there is not allot at 212 deg that interests me and that should help with Europe, I think. > > The next one is 78 deg (antenna runs from 122 to 302 deg) which cuts across the US through North Carolina, Bermuda and on to South Africa. The other side, 258 deg, runs through the Solomon Islands and right down the middle of Australia to Perth. > > I know the lobes will spread way out from these bearings over these long distances but these numbers are a starting point. The antennas will also cross forming a pattern similar to an asterisk on my roof/lot, a good thing I am guessing. > > I was thinking about Inverted V's for most of these until I checked what the side lobes would pick-up. On the 118 deg antenna it would be the South Pacific (no problem) and Europe (big interference problem while shooting for C/S America and SE Asia). > > The 32 deg would pick-up Japan, SE Asia on one side lobe and Mexico, Central America on the other. Too many unwanted signals if I am trying for Europe. > > The 78 deg side lobes would pick-up Alaska, central Russia and west India on one side and the South Pacific, places like Pitcairn, and on to Antarctica. Maybe an inverted V would be OK on this one. > > The Diversity may be a big inverted V or just an L shape long wire. I laid out a spread sheet with the lengths for a Dipole plus 15 deg, 22 deg, 30 deg, 37 deg, 45 deg, 60 deg and 75 deg inverted V's from 160 to 2 meters using the center of the Extra class bands (my next conquest) looking for some magic number. Nothing jumps out at me but of course a ¼ wave 80 is close to a ½ wave 40, a ½ 60, ¼ 30 and so on. I think I can squeeze in a ¼ wave 80 meter dipole (~31.2 feet/side) in most directions and maybe a shorter one above this (easiest for me but technically wrong?). The longer one higher may be possible but won't be easy. 160 meters will be another project for another day. > > > > So my questions are: > > 1) What length would be best and give me the use of the most bands? Remember, I have a limited space. > > 2) How far from the dipole should a reflector be. It should be about 5% longer and grounded, right? > > 3) The auto-tuner on the K3 is amazing. Is it easier for it to tune an antenna that is to long or to short? I'm guessing long but I am not certain. > > 4) Any suggestions on which band/antenna length is best for these targets? I am mostly active late afternoon and evening (till about 10 PST) and mornings after 6. > > Thanks, > > Clint KI6SSN > > > > __________ Information from ESET NOD32 Antivirus, version of virus signature database 4687 (20091214) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > > ______________________________________________________________ > 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 > ______________________________________________________________ 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 |
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I have very limited space plus hoa restrictions; the center /feedpoint
of the dipoles is only fourteen feet high. With this antenna, my K3, or it's predecessor, a very modified FT-101E, I've worked 111 DXCC entities since erecting it in early July. Since these photos were made, I've added WARC bands and am in process of adding 80 and 160 by adding another set of elements roughly in size and adding a loading coil in the center of each. 73, Dunc, W5DC See: http://vibrotek.com/w5dc/w5dcant.html . See: Duncan Carter wrote: > If you are mainly interested in working DX and especially if you are > limited in height, you can also install the parallel dipoles > vertically, more of less. > > > Eric Tichansky wrote: >> In a space limited situation, a parallel dipole (or inverted-V) does >> well. Just calculate your 1/2 wave lengths for each band connect them >> to a common feedpoint. Use small diameter PVC for spreaders. Even on a >> small lot, you could get away with an 80-10 parallel (fan) inverted-V. >> The ends of the 80m elements can be bent towards the ground, sideways, >> etc. Trimming each band's elements can be tedious, but you could just >> live with the cut-by-formula mismatch and use the tuner, you'll be in >> the general ballpark. >> >> As far as position/bearing, unless you are erecting nearly flat-top >> dipoles and at decent heights (ie. 60ft on 40M), you're not going to see >> any significant directivity or pronounced broadside pattern. An >> inverted-V approaches a more omni-directional pattern and low heights >> produce higher angle (ie. cloud burner) radiation. Add in objects >> around the antenna and all kinds of weird things start to happen (ie >> rain gutters, metal roof ridges, etc.) Check this out for relative >> patterns vs. height, referenced to 40M: http://www.qsl.net/aa3rl/ant2.html >> >> Reflectors/directors can be added to an inverted-V setup, and do work >> well for directivity, but again, the resulting radiation angles will >> depend on height. >> >> For diversity on a small lot, I would try a loop or a vertical to >> compliment the dipole(s)/inverted-V. >> >> GL es 73 - no3m >> >> Clint wrote: >> >>> Fellow Elecrafters, >>> >>> I have a feeling this may open the flood gates but here goes. >>> >>> I am a newbie Ham but a long time SWL going back to my Knight Kit Star Roamer. I am fixin' to set-up my antenna farm. OK, it will be more like an antenna garden as I have a small house and lot. My K3/100 has a KAT3 and KRX3. I plan on using 3 Dipoles and maybe an inverted V for diversity receive (what a great feature). I got on Google Earth and plotted out the areas I am interested in. I live just up the street from Elecrafts new HQ (talk about fast service) on the central coast of California (CM96CX). >>> >>> A bearing of 118 deg (antenna runs from 28 to 208 deg) cuts across Central America and South America on one side and across Manila and Singapore, skirting Japan, on the other (298 deg). This is a great coverage for me as I used to live in Singapore and spent lots of time in Asia (work) and Central America (not work). >>> >>> The next one is 32 deg (antenna runs from 122 to 302 deg) which cuts through London and Rome on to the Middle East. The other side is not too much, Tahiti and the South Pacific. I am thinking of a reflector on this one as there is not allot at 212 deg that interests me and that should help with Europe, I think. >>> >>> The next one is 78 deg (antenna runs from 122 to 302 deg) which cuts across the US through North Carolina, Bermuda and on to South Africa. The other side, 258 deg, runs through the Solomon Islands and right down the middle of Australia to Perth. >>> >>> I know the lobes will spread way out from these bearings over these long distances but these numbers are a starting point. The antennas will also cross forming a pattern similar to an asterisk on my roof/lot, a good thing I am guessing. >>> >>> I was thinking about Inverted V's for most of these until I checked what the side lobes would pick-up. On the 118 deg antenna it would be the South Pacific (no problem) and Europe (big interference problem while shooting for C/S America and SE Asia). >>> >>> The 32 deg would pick-up Japan, SE Asia on one side lobe and Mexico, Central America on the other. Too many unwanted signals if I am trying for Europe. >>> >>> The 78 deg side lobes would pick-up Alaska, central Russia and west India on one side and the South Pacific, places like Pitcairn, and on to Antarctica. Maybe an inverted V would be OK on this one. >>> >>> The Diversity may be a big inverted V or just an L shape long wire. I laid out a spread sheet with the lengths for a Dipole plus 15 deg, 22 deg, 30 deg, 37 deg, 45 deg, 60 deg and 75 deg inverted V's from 160 to 2 meters using the center of the Extra class bands (my next conquest) looking for some magic number. Nothing jumps out at me but of course a ¼ wave 80 is close to a ½ wave 40, a ½ 60, ¼ 30 and so on. I think I can squeeze in a ¼ wave 80 meter dipole (~31.2 feet/side) in most directions and maybe a shorter one above this (easiest for me but technically wrong?). The longer one higher may be possible but won't be easy. 160 meters will be another project for another day. >>> >>> >>> >>> So my questions are: >>> >>> 1) What length would be best and give me the use of the most bands? Remember, I have a limited space. >>> >>> 2) How far from the dipole should a reflector be. It should be about 5% longer and grounded, right? >>> >>> 3) The auto-tuner on the K3 is amazing. Is it easier for it to tune an antenna that is to long or to short? I'm guessing long but I am not certain. >>> >>> 4) Any suggestions on which band/antenna length is best for these targets? I am mostly active late afternoon and evening (till about 10 PST) and mornings after 6. >>> >>> Thanks, >>> >>> Clint KI6SSN >>> >>> >>> >>> __________ Information from ESET NOD32 Antivirus, version of virus signature database 4687 (20091214) __________ >>> >>> The message was checked by ESET NOD32 Antivirus. >>> >>> http://www.eset.com >>> >>> ______________________________________________________________ >>> 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 >>> >>> >> >> ______________________________________________________________ >> 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 >> >> > ______________________________________________________________ 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 |
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In reply to this post by Clint-2
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In reply to this post by Clint-2
Hello Clint,
While planning your antenna farm, have you considered using an antenna modelling program such as EZNEC which could be of great help to you. A free version comes with the ARRL Antenna Handbook. Due to the effect of nearby objects such as above ground power lines, metal gutters etc etc and trees on antennas, such a program cannot be expected to tell the whole truth unless these objects are included in the model, which can be difficult to do properly, but it can and usually does show the effect of other nearby antennas on the pattern of the antenna in use. Unfortunately the geographical bearing to a distant DX station is not always the same bearing at which the signal actually arrives. For example here on 40m the short path into CA is often "skewed" by as much as 50 degrees via Central /S.America. Also the vertical angle of arrival of the closer East Coast stations can vary considerably - often very high angle. The variation in bearing and angle of arrival of long distance DX stations here on 15m is usually very much less. So my suggestion FWIW is that you consider using EZNEC to plan your farm, put up an antenna which serves your main operating interests and directions (within the imposed constraints), and add other antennas ONLY if they do not compromise the performance of your "main" antenna. This does not answer your questions directly, but if you use EZNEC you should be able to get some ideas. 73, Geoff GM4ESD Clint <[hidden email]> wrote on Monday, December 14, 2009 at 6:17 PM Fellow Elecrafters, I have a feeling this may open the flood gates but here goes. I am a newbie Ham but a long time SWL going back to my Knight Kit Star Roamer. I am fixin' to set-up my antenna farm. OK, it will be more like an antenna garden as I have a small house and lot. My K3/100 has a KAT3 and KRX3. I plan on using 3 Dipoles and maybe an inverted V for diversity receive (what a great feature). I got on Google Earth and plotted out the areas I am interested in. I live just up the street from Elecrafts new HQ (talk about fast service) on the central coast of California (CM96CX). <snip> ______________________________________________________________ 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 |
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In reply to this post by AC7AC
And, if you don't have enough space for a radial field on the ground,
try a vertical doublet, center fed with balanced line for multi-band operation. I've been using one for years which is 32 ft. tall and can be loaded easily from 30 meters to 15 meters. Much better for dx than my low dipole and the elevated feedpoint (at 16 ft.) seems to help overcome ground clutter (enclosing block walls etc.). The wire is supported by a 32 ft. telescoping fiberglass pole, with footprint less than one square foot! Bob NW8L On Mon, Dec 14, 2009 at 12:58 PM, Ron D'Eau Claire <[hidden email]> wrote: > As Ken mentioned, height is an important factor in a horizontal or > semi-horizontal antenna. There's limited "gain" in any direction at low > angles unless the radiator is 1/2 wavelength above ground. That's why most > of us have to live with little directivity on the lower bands. > > The option is to consider verticals. Unless you are living on salt water (or > atop a sheet of copper), or can make the vertical a full 1/2 wave high, the > vertical won't be as efficient as doublet or dipole, but a vertical will > produce typically much better signals at lower angles of radiation than a > horizontal antenna (under 1/2 wave high) and doesn't require a huge > 'footprint'. Also you can phase multiple verticals for directivity and even > design them so you can use them for supports for horizontal wires on the > higher bands. > > You've probably noticed that 45 foot verticals are being heavily promoted > these days. That's an old design that is very handy for limited space. It > provides low angles of radiation on all bands up through 20 meters where > it's 5/8 wavelength high (on bands where it's more than 5/8 wavelength the > angle of the main lobe rises from the horizontal and minor lobes appear at > high angles). Down on 80 meters it's just a bit shy of 1/4 wavelength. With > a good ground system it can produce excellent results down there and even on > 160 - especially when compared with the short, low (in wavelengths above > ground) antennas most of us are forced to use on those bands > > Ron AC7AC 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 |
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160-10 One antenna. I have a Zero Five 43 ft vertical and the matching network described in Dec QST for 80/160. Most bands are close to flat and only one band needs one touch of the K3 ATU. Works very well. I have a Pro 67 B Mosley beam at 72 feet and when switching back and forth, it surprises me. Small yard space. Drive some ground rods down and put out a few wires buried in the soil. Phil Philip LaMarche LaMarche Enterprises, Inc. www.instantgourmetspices.com www.w9dvm.com 800-395-7795 pin 02 727-944-3226 FAX 727-937-8834 NASFT 30210 K3 #1605 CCA 98 00827 CRA 1701 W9DVM -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Bob Cunnings Sent: Monday, December 14, 2009 3:48 PM To: [hidden email] Subject: Re: [Elecraft] antenna farm And, if you don't have enough space for a radial field on the ground, try a vertical doublet, center fed with balanced line for multi-band operation. I've been using one for years which is 32 ft. tall and can be loaded easily from 30 meters to 15 meters. Much better for dx than my low dipole and the elevated feedpoint (at 16 ft.) seems to help overcome ground clutter (enclosing block walls etc.). The wire is supported by a 32 ft. telescoping fiberglass pole, with footprint less than one square foot! ______________________________________________________________ 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 |
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In reply to this post by Bob Cunnings NW8L
Duncan Carter wrote:
> Even if you don't have space for a large radial field, you are apt to > do better with elevated radials, even one "radial" ( the lower half of > the dipoles) as I have. Putting wire in or on the ground is mainly > useful for keeping earthworms warm. To read a lively debate on this > subject which includes links to two excellent technical references, > see all three pages of: http://www.eham.net/forums/Elmers/237953 73, Dunc, W5DC > > Bob Cunnings wrote: >> And, if you don't have enough space for a radial field on the ground, >> try a vertical doublet, center fed with balanced line for multi-band >> operation. I've been using one for years which is 32 ft. tall and can >> be loaded easily from 30 meters to 15 meters. Much better for dx than >> my low dipole and the elevated feedpoint (at 16 ft.) seems to help >> overcome ground clutter (enclosing block walls etc.). The wire is >> supported by a 32 ft. telescoping fiberglass pole, with footprint less >> than one square foot! >> >> Bob NW8L >> >> On Mon, Dec 14, 2009 at 12:58 PM, Ron D'Eau Claire <[hidden email]> wrote: >> >>> As Ken mentioned, height is an important factor in a horizontal or >>> semi-horizontal antenna. There's limited "gain" in any direction at low >>> angles unless the radiator is 1/2 wavelength above ground. That's why most >>> of us have to live with little directivity on the lower bands. >>> >>> The option is to consider verticals. Unless you are living on salt water (or >>> atop a sheet of copper), or can make the vertical a full 1/2 wave high, the >>> vertical won't be as efficient as doublet or dipole, but a vertical will >>> produce typically much better signals at lower angles of radiation than a >>> horizontal antenna (under 1/2 wave high) and doesn't require a huge >>> 'footprint'. Also you can phase multiple verticals for directivity and even >>> design them so you can use them for supports for horizontal wires on the >>> higher bands. >>> >>> You've probably noticed that 45 foot verticals are being heavily promoted >>> these days. That's an old design that is very handy for limited space. It >>> provides low angles of radiation on all bands up through 20 meters where >>> it's 5/8 wavelength high (on bands where it's more than 5/8 wavelength the >>> angle of the main lobe rises from the horizontal and minor lobes appear at >>> high angles). Down on 80 meters it's just a bit shy of 1/4 wavelength. With >>> a good ground system it can produce excellent results down there and even on >>> 160 - especially when compared with the short, low (in wavelengths above >>> ground) antennas most of us are forced to use on those bands >>> >>> Ron AC7AC >>> >> ______________________________________________________________ >> 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 >> >> > ______________________________________________________________ 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 |
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In reply to this post by Clint-2
Hello Clint and welcome aboard,
Your ultimate ambitions and desires will have to take second seat to the restrictions of your location. Not withstanding antenna/tower height restrictions in the county and city you are in. First off, being able to select a compass quadrant on a small lot is probably not possible, unless you can erect a tower or have enough room for a 4 square or even a 2 element vertical. Wire beams take ROOM. Even an inverted V on 80 meter is at least 95 feet across the bottom. Ok, enough negative thinking. Some observations. Many bands are open to different areas of the world at different times of the day. Gray zone etc. So on 160, 80 and 40 meters paths are likely to be very good in one direction and not so good in the opposite. Get the idea? I would consider your "antenna garden" a work in process and start with something that works good with the space you have and develop a plan to see what you can work and when. A years worth of investigation will tell you a lot on where the conflicts are and where the sweet spots are. So where do you start. A good dipole for DX should be at least 1/2 wave above ground and the DX'ers won't even do it that low. That is 120'+ on 80 M etc. Ok, an inverted V can have the apex lower, like 50 to 60 feet. so you still need a center support. You can do this and feed the inverted V on multiple bands with a little clever work on the feed line length and a good match box. Or you could put in traps in the inverted V for other bands and loading coils for 160. Not super class but functional. Frankly I would start there. It is the simplest and most effective antenna for a small lot and a conservative budget. After a season with this, you can decide where you want to "grow" your farm and on what bands that your budget can afford. Good luck. Mel, K6KBE --- On Mon, 12/14/09, Clint <[hidden email]> wrote: From: Clint <[hidden email]> Subject: [Elecraft] antenna farm To: [hidden email] Date: Monday, December 14, 2009, 10:17 AM Fellow Elecrafters, I have a feeling this may open the flood gates but here goes. I am a newbie Ham but a long time SWL going back to my Knight Kit Star Roamer. I am fixin' to set-up my antenna farm. OK, it will be more like an antenna garden as I have a small house and lot. My K3/100 has a KAT3 and KRX3. I plan on using 3 Dipoles and maybe an inverted V for diversity receive (what a great feature). I got on Google Earth and plotted out the areas I am interested in. I live just up the street from Elecrafts new HQ (talk about fast service) on the central coast of California (CM96CX). A bearing of 118 deg (antenna runs from 28 to 208 deg) cuts across Central America and South America on one side and across Manila and Singapore, skirting Japan, on the other (298 deg). This is a great coverage for me as I used to live in Singapore and spent lots of time in Asia (work) and Central America (not work). The next one is 32 deg (antenna runs from 122 to 302 deg) which cuts through London and Rome on to the Middle East. The other side is not too much, Tahiti and the South Pacific. I am thinking of a reflector on this one as there is not allot at 212 deg that interests me and that should help with Europe, I think. The next one is 78 deg (antenna runs from 122 to 302 deg) which cuts across the US through North Carolina, Bermuda and on to South Africa. The other side, 258 deg, runs through the Solomon Islands and right down the middle of Australia to Perth. I know the lobes will spread way out from these bearings over these long distances but these numbers are a starting point. The antennas will also cross forming a pattern similar to an asterisk on my roof/lot, a good thing I am guessing. I was thinking about Inverted V's for most of these until I checked what the side lobes would pick-up. On the 118 deg antenna it would be the South Pacific (no problem) and Europe (big interference problem while shooting for C/S America and SE Asia). The 32 deg would pick-up Japan, SE Asia on one side lobe and Mexico, Central America on the other. Too many unwanted signals if I am trying for Europe. The 78 deg side lobes would pick-up Alaska, central Russia and west India on one side and the South Pacific, places like Pitcairn, and on to Antarctica. Maybe an inverted V would be OK on this one. The Diversity may be a big inverted V or just an L shape long wire. I laid out a spread sheet with the lengths for a Dipole plus 15 deg, 22 deg, 30 deg, 37 deg, 45 deg, 60 deg and 75 deg inverted V's from 160 to 2 meters using the center of the Extra class bands (my next conquest) looking for some magic number. Nothing jumps out at me but of course a ¼ wave 80 is close to a ½ wave 40, a ½ 60, ¼ 30 and so on. I think I can squeeze in a ¼ wave 80 meter dipole (~31.2 feet/side) in most directions and maybe a shorter one above this (easiest for me but technically wrong?). The longer one higher may be possible but won't be easy. 160 meters will be another project for another day. So my questions are: 1) What length would be best and give me the use of the most bands? Remember, I have a limited space. 2) How far from the dipole should a reflector be. It should be about 5% longer and grounded, right? 3) The auto-tuner on the K3 is amazing. Is it easier for it to tune an antenna that is to long or to short? I'm guessing long but I am not certain. 4) Any suggestions on which band/antenna length is best for these targets? I am mostly active late afternoon and evening (till about 10 PST) and mornings after 6. Thanks, Clint KI6SSN __________ Information from ESET NOD32 Antivirus, version of virus signature database 4687 (20091214) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ______________________________________________________________ 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 ______________________________________________________________ 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 |
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In reply to this post by Geoffrey Mackenzie-Kennedy
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In reply to this post by Geoffrey Mackenzie-Kennedy
On Dec 14, 2009, at 12:45 PM, Geoffrey Mackenzie-Kennedy wrote:
> While planning your antenna farm, have you considered using an antenna > modelling program such as EZNEC which could be of great help to you. A free > version comes with the ARRL Antenna Handbook. This is the approach I am taking, though I ended up buying EZNEC+ as I have a lot of architectural metal in my 3-story town home over the Santa Cruz small craft harbor. The first story is also stucco, which has a bunch of wire in it as well, as are the other nearby homes in my complex. My goals are to try and determine why the placement of my current wire dipoles is so poor, and then to see if I can model something that will have theoretically better performance before I go through the effort of constructing and hanging my next low-visibility antenna(s). So far, just looking at the plots as I add more of the large bits of metal in my home to the model has been instructive. Byron KI6NUL p.s. One of the first things in the EZNEC instructions is a word from the author about how amateurs with limited space often wonder why their 3 antennas do not work well, and he points out they really have 1 antenna with 3 feed points due to their spacing. ______________________________________________________________ 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 |
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Byron Servies wrote:
> On Dec 14, 2009, at 12:45 PM, Geoffrey Mackenzie-Kennedy wrote: > This is the approach I am taking, though I ended up buying EZNEC+ as I have a lot of > architectural metal in my 3-story town home over the Santa Cruz small craft harbor. > The first story is also stucco, which has a bunch of wire in it as well, as are the > other nearby homes in my complex. If that's salt water, try a vertical! -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ______________________________________________________________ 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 |
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In reply to this post by Byron N6NUL
When I first put up my vertical, I only had 40 and 20 meters and mounted
them on the opposite of my house from the current feed point location, that is, in between and close to the rain gutter and the metal chimney liner. The feed point resistance on 40 was as expected but the feed point resistance on 20 was about 1/3 of what I expected. Moving the center parts and feed point to the opposite side of the house gave feedpoint impedances as expected. I have no idea if the chimney liner is grounded or not. I haven't modeled the antenna but I still know how to calculate radiation restiances. Back in the day "when I had hair on top of my head) I was an antenna designer for Collins and for Hy-Gain and a consultant afterwards. Dunc, W5DC Byron Servies wrote: > On Dec 14, 2009, at 12:45 PM, Geoffrey Mackenzie-Kennedy wrote: > > >> While planning your antenna farm, have you considered using an antenna >> modelling program such as EZNEC which could be of great help to you. A free >> version comes with the ARRL Antenna Handbook. >> > > This is the approach I am taking, though I ended up buying EZNEC+ as I have a lot of architectural metal in my 3-story town home over the Santa Cruz small craft harbor. The first story is also stucco, which has a bunch of wire in it as well, as are the other nearby homes in my complex. > > My goals are to try and determine why the placement of my current wire dipoles is so poor, and then to see if I can model something that will have theoretically better performance before I go through the effort of constructing and hanging my next low-visibility antenna(s). > > So far, just looking at the plots as I add more of the large bits of metal in my home to the model has been instructive. > > Byron KI6NUL > p.s. One of the first things in the EZNEC instructions is a word from the author about how amateurs with limited space often wonder why their 3 antennas do not work well, and he points out they really have 1 antenna with 3 feed points due to their spacing. > ______________________________________________________________ > 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 > > ______________________________________________________________ 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 |
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In reply to this post by AC7AC
On Mon, 14 Dec 2009 11:58:26 -0800, "Ron D'Eau Claire" <[hidden email]>
wrote: Yes you did open the flood gate. Antenna opinions are like noses. Every one has one... As Ron say's, If you can't get a dipole up 1/2wl you will be sending most of your radiated output and receiving at high angles, which won't be what you want unless you plan to do a lot of local rag chewing. Here's a real life test that I made: I have an 80m half sloper on my tower sloping from 38 feet which does pretty well working 360 degrees around (the tower becomes the radiator when using this type of sloper). A couple of weeks ago I put an 80m inverted vee up and compared the two. The inverted vee could not even hear the European signals, but could hear signals within a few hundred miles very well. The reason for that was because the inverted V (at 38 feet) was radiating the largest amount of energy straight up at 90 degrees (verified with EZNEC 5.0). 73, Tom, N5GE [hidden email] K3 #806 with SUB RX, K3 #1055, PR6, XV144, XV432, KRC2, W1, 2 W2's and other small kits 1 K144XV on order http://www.n5ge.com http://www.swotrc.net >As Ken mentioned, height is an important factor in a horizontal or >semi-horizontal antenna. There's limited "gain" in any direction at low >angles unless the radiator is 1/2 wavelength above ground. That's why most >of us have to live with little directivity on the lower bands. > >The option is to consider verticals. Unless you are living on salt water (or >atop a sheet of copper), or can make the vertical a full 1/2 wave high, the >vertical won't be as efficient as doublet or dipole, but a vertical will >produce typically much better signals at lower angles of radiation than a >horizontal antenna (under 1/2 wave high) and doesn't require a huge >'footprint'. Also you can phase multiple verticals for directivity and even >design them so you can use them for supports for horizontal wires on the >higher bands. > >You've probably noticed that 45 foot verticals are being heavily promoted >these days. That's an old design that is very handy for limited space. It >provides low angles of radiation on all bands up through 20 meters where >it's 5/8 wavelength high (on bands where it's more than 5/8 wavelength the >angle of the main lobe rises from the horizontal and minor lobes appear at >high angles). Down on 80 meters it's just a bit shy of 1/4 wavelength. With >a good ground system it can produce excellent results down there and even on >160 - especially when compared with the short, low (in wavelengths above >ground) antennas most of us are forced to use on those bands > >Ron AC7AC ______________________________________________________________ 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
Amateur Radio Operator N5GE
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Yes your inverted-vee has max gain at 90 degrees elevation, but you (editorial sense) still need to compare its gain in the direction of interest with a vertical (or near vertical) over the same ground and with a real-world ground system.
Wes N7WS --- On Tue, 12/15/09, Radio Amateur N5GE <[hidden email]> wrote: > From: Radio Amateur N5GE <[hidden email]> > Subject: Re: [Elecraft] antenna farm > To: [hidden email] > Date: Tuesday, December 15, 2009, 12:40 PM > On Mon, 14 Dec 2009 11:58:26 -0800, > "Ron D'Eau Claire" <[hidden email]> > wrote: > > Yes you did open the flood gate. Antenna opinions are > like noses. > Every one has one... > > As Ron say's, If you can't get a dipole up 1/2wl you > will be sending > most of your radiated output and receiving at high angles, > which won't > be what you want unless you plan to do a lot of local rag > chewing. > > Here's a real life test that I made: > > I have an 80m half sloper on my tower sloping from 38 feet > which does > pretty well working 360 degrees around (the tower becomes > the radiator > when using this type of sloper). A couple of weeks > ago I put an 80m > inverted vee up and compared the two. The inverted > vee could not even > hear the European signals, but could hear signals within a > few hundred > miles very well. The reason for that was because the > inverted V (at > 38 feet) was radiating the largest amount of energy > straight up at 90 > degrees (verified with EZNEC 5.0). > > 73, > > Tom, N5GE > > [hidden email] > K3 #806 with SUB RX, K3 #1055, PR6, > XV144, XV432, KRC2, > W1, 2 W2's and other small kits > > 1 K144XV on order > > http://www.n5ge.com > http://www.swotrc.net > > >As Ken mentioned, height is an important factor in a > horizontal or > >semi-horizontal antenna. There's limited "gain" in any > direction at low > >angles unless the radiator is 1/2 wavelength above > ground. That's why most > >of us have to live with little directivity on the lower > bands. > > > >The option is to consider verticals. Unless you are > living on salt water (or > >atop a sheet of copper), or can make the vertical a > full 1/2 wave high, the > >vertical won't be as efficient as doublet or dipole, > but a vertical will > >produce typically much better signals at lower angles > of radiation than a > >horizontal antenna (under 1/2 wave high) and doesn't > require a huge > >'footprint'. Also you can phase multiple verticals for > directivity and even > >design them so you can use them for supports for > horizontal wires on the > >higher bands. > > > >You've probably noticed that 45 foot verticals are > being heavily promoted > >these days. That's an old design that is very handy for > limited space. It > >provides low angles of radiation on all bands up > through 20 meters where > >it's 5/8 wavelength high (on bands where it's more than > 5/8 wavelength the > >angle of the main lobe rises from the horizontal and > minor lobes appear at > >high angles). Down on 80 meters it's just a bit shy of > 1/4 wavelength. With > >a good ground system it can produce excellent results > down there and even on > >160 - especially when compared with the short, low (in > wavelengths above > >ground) antennas most of us are forced to use on those > bands > > > >Ron AC7AC > > ______________________________________________________________ > 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 > ______________________________________________________________ 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 |
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