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6

From some research, beam antennas only seem to come as monoband antennas. Not true — actually 20/15/10m tri-band beams are very popular. Multi-band yagis come in two basic flavors. Trapped. Works on the same principle as a trap vertical to alter the effective electrical length of the elements at different frequencies, except there are way more elements to ...


5

The wavelength at 1 Hz is several times greater than the circumference of the Earth. At these frequencies, one arguably can't even have an "antenna" for terrestrial communication, since any two such antennas would be so close together they would be more like two plates of a capacitor or two windings of an inductor than an antenna. 1 Hz isn't even ...


4

Engineer999. The driven element of a yagi antenna is normally a half wave dipole, and it's true that a dipole antenna is resonant on multiple harmonically related frequencies. An ideal 10 m long dipole for example is resonant on 15 MHz, 30 MHz, 60 MHz, 120 MHz etc. However the distances between the elements along the boom of a yagi required to provide ...


3

First check your local regulations. Some specify the minimum gauge for wire antennas. For example NEC Article 810 specifies a minimum of 14 AWG for wire receive antennas. For temporary antennas such a POTA activation using a smaller gauge would be acceptable. I've also know hams to ignore the local regulations. If transmitting check that is can handle the ...


2

"RF ground" usually means "something that is at the same potential as the soil". This is important because if you have a wire (such as your feedline, for example) which is not at ground potential, then there exists a non-zero electromagnetic field between that wire and the soil. That means the feedline is radiating/receiving, which is ...


2

If you feed a wire antenna at its center with open wire or balanced line, where the length of the antenna may or may not be designed to be resonant on any operating frequency, then the result is usually called a doublet antenna. A doublet’s length is usually chosen so that it isn’t anti-resonant (a full wavelength, etc.) on any of the desired operating ...


2

This is a harder question to answer than you think for a number of reasons. I'll start off with the ideal answer: The Diamond RH-771 claims that it has 2.15 dBi gain at 70cm (or 0 dBd). Most rubber ducks are significantly worse than quarter wave antennas, and often exhibit negative gain. A short antenna like the SRH-701 has no gain (or -2.15 dBd). The ...


1

It may be great, it may not... that's definitely an empirical question due to the many factors: how much of the xmit current on the ground leg will be parallel and next to your vertical? this could cause destructive interference and make the antenna pattern more directional. are there other currents on the ground that will make their way into your antenna ...


1

A resonant 20 meter monoband Yagi will not work on 10 meters. Have you considered a 3-band 10-15-20 Tri-bander? It is a beam, and definitely not a monobander. There are also smaller tri-band directional beams, such as the Hexbeam.


1

If you are using copper wire, 14 gauge is about as small as you want to get. Be aware, however, that if you hang a long copper wire that thin, it will stretch. This is not a big deal as long as you don't care about its length for antenna purposes. If you use something like copper clad steel, you can go as low as 16 or 18 gauge and it will still support its ...


1

I think this is the wrong question. You ask does antenna X exist, but what you really should be asking is Given this configuration, can it be made resonant with a good SWR. Random wire antennas exist. All you need to make anything work is a good antenna tuner. Of course, this doesn't guarantee efficiency, radiation pattern, or that it radiates at all. ...


1

For HF (e.g., 3MHz), the skin depth effect is <50 x 10^-6 m even for aluminum, and it is thiner for higher frequencies, so braid should be fine. The bandwidth of the J-pole is affected by the diameter of the radiating element. The band is wider at higher frequencies, so to cover the 2m amateur band, you need about the diameter of rg58 shield. HF bands, ...


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