Antenna suggestions, resent
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I just realized that my previous message was sent in html format. Which
means that the reflector stripped the text! That explains some of the answers... Here is what I meant to ask: ---------------------------------------------------------------------- I am moving to an apartment on the top floor of a 10 story building. I have access to the roof which has a 30' x 10' flat space. On one edge of this space is a building 9' high with a flat roof of about 10' x 20'. I can put up antennas on top of this little building and on the flat area mentioned above. But there is a catch: the antenna has to be either a wire antenna, or substantially vertical. If vertical, it can't exceed 29' in height above the roof of the small building. Beams not allowed! I want to operate on 40 through 15 meters. The antenna needs to be able to handle 1500w. I prefer horizontal antennas because of the extra gain and lower noise pickup. I prefer a balanced antenna because of noise and RFI considerations. But I'll consider other options if there are overriding advantages. Suggestions? -- 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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Don't discard the magnetic loop as a possibility:
http://radiopreppers.com/index.php/topic,180.0.html Gil. -- PGP Key: http://keskydee.com/gil.asc ______________________________________________________________ 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 |
Re: Antenna suggestions, resent
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The problem with the magloop is that it's hard to build one that can
handle more than about 100 watts. The voltage across the capacitor gets astronomical! On 9/28/13 11:53 AM, Gil G. wrote: > Don't discard the magnetic loop as a possibility: > > http://radiopreppers.com/index.php/topic,180.0.html > > Gil. > -- > PGP Key: http://keskydee.com/gil.asc > ______________________________________________________________ > 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 > -- 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 |
Re: Antenna suggestions, resent
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I'm no expert on loops, but isn't the voltage lower on a BIG loop?
On 9/28/2013 12:22 PM, Vic, K2VCO wrote: > The problem with the magloop is that it's hard to build one that can > handle more than about 100 watts. The voltage across the capacitor > gets astronomical! > > On 9/28/13 11:53 AM, Gil G. wrote: >> Don't discard the magnetic loop as a possibility: >> >> http://radiopreppers.com/index.php/topic,180.0.html >> >> Gil. >> -- >> PGP Key: http://keskydee.com/gil.asc >> ______________________________________________________________ >> 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 |
Re: Antenna suggestions, resent
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A so-called "magnetic" loop is defined as one smaller than about 1/3 wl
in circumference. Bigger than that is a loop, but has a different pattern -- and you are correct that the voltage across tuning components is lower. On 9/28/13 12:38 PM, Lynn W. Taylor, WB6UUT wrote: > I'm no expert on loops, but isn't the voltage lower on a BIG loop? > > On 9/28/2013 12:22 PM, Vic, K2VCO wrote: >> The problem with the magloop is that it's hard to build one that can >> handle more than about 100 watts. The voltage across the capacitor >> gets astronomical! >> >> On 9/28/13 11:53 AM, Gil G. wrote: >>> Don't discard the magnetic loop as a possibility: >>> >>> http://radiopreppers.com/index.php/topic,180.0.html >>> >>> Gil. >>> -- >>> PGP Key: http://keskydee.com/gil.asc >>> ______________________________________________________________ >>> 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 -- 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 Vic Rosenthal
Certainly, but I've reached Russia with mine (21ft. perimeter) using 5W with the loop inside the house on the second floor, turned the wrong way.. So, they do work really well.. If you're into contesting, I understand, otherwise, you don't need more than a few Watts CW, maybe 25 for SSB. You can find vacuum capacitors on Ebay for $150.. I use a $60 air capacitor rated for 4.5KV, used it with my 12W KX3, no arcing..
Gil. -- PGP Key: http://keskydee.com/gil.asc On Sep 28, 2013, at 3:22 PM, Vic, K2VCO wrote: > The problem with the magloop is that it's hard to build one that can handle more than about 100 watts. The voltage across the capacitor gets astronomical! ______________________________________________________________ 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 Vic Rosenthal
I'd stay away from a vertical. You'll have problems with manmade interference in an apartment complex and vertical polarization will make it worse. I'd go for a 44' doublet/inv-V supported by a nonconductive mast and fed with twinlead...or an OCF fed with coax. 73, Bill W4ZV 73, Bill W4ZV |
Re: Antenna suggestions, resent
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In reply to this post by Vic Rosenthal
Hello Vic,
If you have not done this already, it would be wise to include in any model all nearby metallic objects such as gutters, downpipes, etc, *before* you cut any wire. Such objects can have a profound effect on the horizontal or vertical pattern (or both) of an antenna, as I am sure you know. If the surface of the roof is metal, then a metal grid can be used to represent the roof. If the roof is made of concrete, brick or stone, the roof becomes more difficult to model. I am not certain that I know how to model concrete, brick or stone objects correctly. 73, Geoff LX2AO On September 28, 2013 at 6:47 AM, Vic, K2VCO wrote: > I am moving to an apartment on the top floor of a 10 story building. I > have access to the roof which has a 30' x 10' flat space. On one edge of > this space is a building 9' high with a flat roof of about 10' x 20'. I > can put up antennas on top of this little building and on the flat area > mentioned above. <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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Hello,
The way I model the ugly stuff is too use the end range of the ground type and see the effect. Depending on the antenna model, AGL etc. The difference can be minor or major. But I use that to see if I am going to have a problem. Mel, K6KBE ________________________________ From: Geoffrey Mackenzie-Kennedy <[hidden email]> To: [hidden email] Cc: elecraft Reflector <[hidden email]> Sent: Sunday, September 29, 2013 8:57 AM Subject: Re: [Elecraft] Antenna suggestions, resent Hello Vic, If you have not done this already, it would be wise to include in any model all nearby metallic objects such as gutters, downpipes, etc, *before* you cut any wire. Such objects can have a profound effect on the horizontal or vertical pattern (or both) of an antenna, as I am sure you know. If the surface of the roof is metal, then a metal grid can be used to represent the roof. If the roof is made of concrete, brick or stone, the roof becomes more difficult to model. I am not certain that I know how to model concrete, brick or stone objects correctly. 73, Geoff LX2AO On September 28, 2013 at 6:47 AM, Vic, K2VCO wrote: > I am moving to an apartment on the top floor of a 10 story building. I > have access to the roof which has a 30' x 10' flat space. On one edge of > this space is a building 9' high with a flat roof of about 10' x 20'. I > can put up antennas on top of this little building and on the flat area > mentioned above. <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 ______________________________________________________________ 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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