Brad, I had a little more time to look at this, and if your individual elements are indeed close to 50 ohms with the other element open circuit, the W7EL Simpfeed system could work quite well. I plug
I had a couple of requests for the location of Simpfeed.exe. There is a link to it in the fourth item at http://www.eznec.com/Amateur/Articles/index.html The program comes in a self-extracting .zip f
Either the shorted half-wave or open quarter-wave is OK. Normal practice is to use a small coil connected to the coax between center conductor and shield, with one or two turns that is just big enoug
I'm not sure that's what Guy was implying. I don't think that there isn't any particular impedance assumed by EZNEC, but it does normally assume that all the power from the source is delivered to the
Although there are no absolutes when it comes to antennas, if you have a rotatable configuration, the straight dipole would be much better, since it will have nice nulls off the ends and slightly mor
That length isn't too random, since it's a quarter-wavelength on 160m, so depending on how you route it, you could think of it as an inverted-L. Your success will depend on how high you can get most
Warren, It sounds like you probably are intending to use 1/4 wl spacing on 40m, which means 3/4 wl on 15m. This is a little wide, but still useable. Once you go past 5/8 wl spacing, the sidelobes sta
There has been some discussion about the Tak-tennas on the TowerTalk list. Start at http://lists.contesting.com/archives//html/Towertalk/2008-04/msg00319.html The comments from K4SAV are especially p
Andrew sent me a copy of his model, which is a non-terminated triangular loop, apex up, fed in the center of the bottom wire, which is 1 meter high. It does appear that the resistance of the wire is
Andy, You can use the same delay lines and phase angles with the 4 Square, but you have to make the length of the diagonal equal to the 80m spacing between elements 1 and 3 in the linear endfire arra
Flam, I modeled this with EZNEC (without the tower) and assumed the 1.5 mm diameter stainless steel wire has a resistivity of 7.2 e-7 ohm-m and relative permeability of 1.02. I estimated about 20 ohm
Using 2.5 mm vs. 1.5 mm diameter copper only increases the gain by about 0.1 dB. The feedpoint R is about 1 ohm lower, and the bandwidth increases by about 4 kHz. The resonance moves up by 13 kHz to
Yes, Flam's 46.5m wire is only about 0.29 wl. However, making it longer would raise the feedpoint Z even higher. There might be a slight improvement in efficiency, but usually most of the extra signa
I tried this in EZNEC and get the same sort of results. With a ~5% smaller director, the F/B is about 3 dB with 12 foot spacing. Decreasing the director spacing improves the F/B very slightly: with 7
Perhaps others can confirm this, but I think the "cable loss mode" requires that the far end be either opened or shorted (to give an infinite SWR or Return Loss = 0 dB at the load), and NOT connected
Doesn't it seem strange that your antenna never actually resonates (X=0)? For a simple quarter wave vertical, you'd expect that if you went high or low enough in frequency, the reactance would go thr
To me, one of the most frustrating limitations of NEC2-based modeling software is its inability to accurately deal with models where conductors of different diameters are joined, especially at right
The consideration of orientation may be a concern where the diameter of the cylinder or the face of the tower approaches a half-wavelength. It's unlikely to have any impact on the MF or HF bands for
Just place a 10 megohm or larger resistor where you are planning to put the trap or relay. Use the Load Dat function in EZNEC to see the voltage across the load. You can also easily model a trap in E
I sent Jim two EZNEC models that demonstrate his questions. If anyone else is interested, respond off list. - 73, Terry N6RY _______________________________________________ Antennaware mailing list A