Hi All, All this talk lately of NVIS antenna work goes along with some antennas and masts I have been building lately to enjoy casual, portable hamming, with some emphasis on cheap antenna plans for
Mark, If you are using a 1/2 wave dipole the wire on the ground should be unbroken and 5% longer. You can run two or three parallel wires spaced a few feet apart or just one wire. If you are using a
In general, you'd want to orient the wires in the direction of current flow, which would be parallel to the radiating element. Nope.. they're laying on the ground, near a dielectric, so at best, you'
Interesting question. I have never reasearched this one, even though I have thought about doing it, so I tried a few quick simulations. At first the suggestion of making the reflector 5% longer seem
Excellent use of modeling.. Note that even in the worst case (20 ft up) the difference is only 1.5 -2 dB, and the fact that it varies fairly quickly indicates that it's quite sensitive to small chang
Jim I also get 3.26MHz resonant frequency for the ground reflector. I don't know how I got the number I quoted, must have done something really funky. Jerry __________________________________________
some antennas and portable hamming, with 80 trunk antenna. or speaker cord, to a 4:1 current Anything can work, but best to use coax. Lamp cord and speaker wire can have significant loss at radio fr
Thank you all for your thoughtful and informative replies. Having a large spool of light wire with which I can easily lay down a screen is the easiest way to go, much like the pattern of cooling coil
Approach it geometrically as a start (even though it's probably not valid electromagnetically).. if you have your antenna up 10 ft, and you're looking at a 45 degree takeoff angle, go out by 45 degre
Seems like this problem should be an easy one to model with AO or similar modeling program. Tell the program the antenna is in free space, then define the antenna and then the screen in the Z-lane be
with AO or similar the antenna and version would be Models do the very worse jobs trying to simulate earth effects. First, we don't know what the ground really is and can't easily measure it. Second
The trick is in adequately modeling the earth losses. Wires close to the ground are always challenging to model, and small changes in the spacing (from earth) or the dielectric properties of the soil
Re: [TowerTalk] Practical Ground Screens for NVIS antennasTom Rauch wrote This is an old old trick people on 75 and 160 meters used (I first learned of it in 1962 or 63), and when doing 3895kc Gator
This is an old old trick people on 75 and 160 meters used (I first learned of it in 1962 or 63), and when doing 3895kc Gator Quarming competitions in the early 70's I experimented extensively with NV