What are some of the advantages and disadvantages of using a vertical antenna on high frequency? Are there any better antenna types that I should use?
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2$\begingroup$ Amateurs: Please do not vote for closing a question just because it feels too basic. The question is relevant and there is a good answer below. $\endgroup$– jkjOct 23, 2013 at 18:05
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$\begingroup$ possible duplicate of Should I chose a vertical or a horizontal antenna? $\endgroup$– on4aaOct 31, 2013 at 23:54
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3 Answers
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The primary advantages of vertical antennas are that they are omnidirectional, and with an appropriate ground plane (radials) yield a low radiation angle; this reduces the number of "hops" that HF signals must make to reach their destination. Ignoring the ground plane, which might be radial wires or metallic screening buried just under the surface, vertical antennas don't take up much space.
The primary disadvantages of vertical antennas are that they are vertically polarized, which makes them more sensitive to man-made noise when used for reception as compared to horizontally-polarized antennas like a dipole, and that they require a good ground plane to be effective when transmitting.
Vertical antennas for the lower bands require a significant mechanical support; for 80m, for example, a quarter-wavelength vertical antenna would be 66' tall. Verticals can be made shorter with top-loading or various tuning schemes, but at the cost of lowered efficiency -- meaning less of the transmitted signal is effectively radiated.
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$\begingroup$ Low-band (160m-80m-40m) vertical antennas are often shortened using coils or top-loading, which also brings the disadvantage of making them quite sharply tuned and narrowband. For example, my Bencher HF6V 6-band vertical is only good for some 60 KHz on 3.5 MHz, so I get to choose if I want to work CW, digital, or some subset of the SSB band. Retuning requires a trip to the roof. Shortened horizontal antennas have the same property, but it's easier to hang a 40-meter wire horizontally than to make it stand upright. $\endgroup$– oh7lzbOct 23, 2013 at 6:59
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Verticals work very well near the sea or salt water lake, your ground radials can be minimal and there is a good 6-10dB uplift in your sent and received signal. This is mainly due to much better ground conductivity and lack of obstructions. The much improved ground conductivity lowers the angle of radiation even more and lowers ground losses considerably.
This is backed up by practice and documented in plenty of articles, books and journals. (Look up Naval shore electronics criteria, it's been digitised by Googl)
To get close to this on dry land, you'll need plenty of ground radials. Rudy Severns, N6LF has done some very good empirical research on this. He suggests using around 32 radials and they don't have to be 1/4 wavelength. Source : https://www.antennasbyn6lf.com/design_of_radial_ground_systems/
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$\begingroup$ Welcome to ham.stackexchange.com! Being a former Navy man myself, I looked up Naval Shore Electronics Criteria, but I couldn't find anything about antenna radials with a quick glance through the document. There was lots about grounding. $\endgroup$ Jun 29, 2020 at 15:24
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One advantage of a vertical antenna (not yet mentioned) is that you can hang a vertical wire over a single tree, while a horizontal antenna needs at least two trees. I use my 50 foot high tree for my vertical 80 meter. Yes, it needs 66 feet of wire to tune properly, but I simply bend the wire over the top and then down. Most of the signal radiates from the lower parts of the vertical antenna, where the most current is.
My method of building the antenna was to throw a string over the tree, and tie the wire to the string and pull up the wire, up and over.
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$\begingroup$ Seems to me that "bending the wire over the top then down would result in considerable cancellation of your radiated signal, resulting in a very odd radiation pattern. $\endgroup$– W0RCFJun 16, 2020 at 15:56