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Antenna R&D
Antenna Gain - Is it the ultimate measure of a better antenna?
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<p>[QUOTE="FOX TV, post: 32525, member: 4493"]<strong>Antennas antennas..ant...</strong></p><p></p><p></p><p></p><p>The one thing I did not mention due to the length of my post is that we went back for a second visit, and the viewer had someone to climb for him and he toted a C4 up with him and sat it on top of the chimney only 5 feet lower than his "100 miler " and it gained almost 5 dB over the C2 we used at 20 feet on the first visit. We hooked the spec analyzer to his antenna on the first visit and saw the echos out at 80 microseconds, with the RF levels of the echos that sometimes spiked almost as strong as the main lobe.</p><p></p><p>The C4 still showed the same time line, but the actual RF level of the echos we saw on his antenna were barely readable on the C4. I am not saying that there are not as good or better antennas, and i have no experience with Wineguard antennas which I understand to be good products. The tapered driven element design of the C series is very innovative, and In theory there should be an electrical path on the driven elements that coincides with every individual channel in the UHF band instead of a wire type element who's performance drops off above and below the design frequency.</p><p></p><p>Your point of elevation difference is valid, and I have seen evidence of this in the past myself, but since we were using a volunteer climber, and time was limited, we did not have a chance to do all of the desired checks we would have liked. This location would be an antenna experimenters dream, but a TV viewers nightmare.</p><p></p><p>I have built my version of the C2 that may violate the patent for the tapered loop design, but my feed point design and reflector is much different than theirs, and the Rhode & Swartz analyzer was used to tune it. My forward gain numbers are about 1/2 dB higher on average, and my reflection or rear rejection numbers are almost 2 dB better.</p><p></p><p>I have been designing or re-designing UHF antennas for years, especially concentrating on the multi-path we see in this area. Check out this article on my Gray-Hoverman re-design in TV Technology Magazine. </p><p></p><p><a href="http://www.tvtechnology.com/article/68820">Polarized Power for TV Broadcasting, by Doug Lung</a></p><p></p><p>The design Doug Lung favored was mine, and this is not to toot my horn, just to give an idea of my background regarding antenna designs for the DTV revolution.</p><p></p><p>I won't flood this forum with posts, but I will chime in on antenna topics, for my efforts are now being aimed towards finding a way to reduce antennas physical size for high VHF, and to be able to build a reflector type antenna that works well on VHF, but is not so big that you would need a section of schedule 40 iron pipe to support it at 30 feet or higher.</p><p></p><p>Also, quads on 10 meters are killer antennas. I used to use an old PDL2 quad on a 50 foot tower, and it would break through the ces pool of noise you hear on contests and pileups etc. The PDL 2 is an old 11 meter antenna that I re-tuned for use on 10. I also installed 1/4 wave radial ground system on the tower that included a chain link fence that was a city block long and ran through 10 backyards before ending at the next block. My wife worked 10 more than I, and she did DX century in less than a year.[/QUOTE]</p><p></p>
[QUOTE="FOX TV, post: 32525, member: 4493"][b]Antennas antennas..ant...[/b] The one thing I did not mention due to the length of my post is that we went back for a second visit, and the viewer had someone to climb for him and he toted a C4 up with him and sat it on top of the chimney only 5 feet lower than his "100 miler " and it gained almost 5 dB over the C2 we used at 20 feet on the first visit. We hooked the spec analyzer to his antenna on the first visit and saw the echos out at 80 microseconds, with the RF levels of the echos that sometimes spiked almost as strong as the main lobe. The C4 still showed the same time line, but the actual RF level of the echos we saw on his antenna were barely readable on the C4. I am not saying that there are not as good or better antennas, and i have no experience with Wineguard antennas which I understand to be good products. The tapered driven element design of the C series is very innovative, and In theory there should be an electrical path on the driven elements that coincides with every individual channel in the UHF band instead of a wire type element who's performance drops off above and below the design frequency. Your point of elevation difference is valid, and I have seen evidence of this in the past myself, but since we were using a volunteer climber, and time was limited, we did not have a chance to do all of the desired checks we would have liked. This location would be an antenna experimenters dream, but a TV viewers nightmare. I have built my version of the C2 that may violate the patent for the tapered loop design, but my feed point design and reflector is much different than theirs, and the Rhode & Swartz analyzer was used to tune it. My forward gain numbers are about 1/2 dB higher on average, and my reflection or rear rejection numbers are almost 2 dB better. I have been designing or re-designing UHF antennas for years, especially concentrating on the multi-path we see in this area. Check out this article on my Gray-Hoverman re-design in TV Technology Magazine. [url=http://www.tvtechnology.com/article/68820]Polarized Power for TV Broadcasting, by Doug Lung[/url] The design Doug Lung favored was mine, and this is not to toot my horn, just to give an idea of my background regarding antenna designs for the DTV revolution. I won't flood this forum with posts, but I will chime in on antenna topics, for my efforts are now being aimed towards finding a way to reduce antennas physical size for high VHF, and to be able to build a reflector type antenna that works well on VHF, but is not so big that you would need a section of schedule 40 iron pipe to support it at 30 feet or higher. Also, quads on 10 meters are killer antennas. I used to use an old PDL2 quad on a 50 foot tower, and it would break through the ces pool of noise you hear on contests and pileups etc. The PDL 2 is an old 11 meter antenna that I re-tuned for use on 10. I also installed 1/4 wave radial ground system on the tower that included a chain link fence that was a city block long and ran through 10 backyards before ending at the next block. My wife worked 10 more than I, and she did DX century in less than a year.[/QUOTE]
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