An interesting NVIS application with circular polarization. It's not clear why they used such "fat" conductors...it seems like they could get plenty of bandwidth for MF broadcasting with simple dipol
A 1.5 wl dipole or inverted vee at modest heights probably won't provide any more usable gain than a half-wave dipole or inverted vee under many circumstances, but it really depends on a lot of varia
per element. I thought I knew the answer to this, but it turned out that modeling showed some surprises (to me anyway). A single 40m inverted-L (up 22 ft, out 13 ft) with four 33 foot long horizontal
Steve, Here a few comments based on some general observations and the EZNEC+ 5.0 model of your tower that I built... That 4'3" base of your tower is definitely part of the antenna, so it, and the 4"
With your 130' spacing (half-wavelength on 80m), as you have seen, you can get nice bi-directional patterns (broadside and endfire) with 0 or 180 degree phasing. On the higher bands, you will get mul
If the top loading wires have to slope down due to a lack of tall supports, it makes sense to use as many wires as possible, so that each one can be shorter (for the same resonant frequency) and thus
This echoes the comments from Roger, VE3ZI. I worked for an electric utility in Oregon in the 1980's and if I were you, I'd stay far away from lines with anything close to 500 kV. All these lines exh
Try 20 kV per bell. 73, Terry N6RY _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contest
I haven't seen any more follow-up regarding optimization of this configuration, but I'll throw in the results of my modeling in EZNEC (NEC-2 engine). I used the parameters discussed, and varied the l
As I understand it, in the absence of non-linearity and anisotropy, reciprocity still applies to cases of multiple refraction. I suspect most cases of apparent "one-way" propagation are due to differ
Another approach, that gives a 50 ohm match without capacitors or transformers, is to use an inverted-L that is about 3.5 feet shorter than resonance and place a shunt coil (about 4.7 uH) across the
Tom, You're doing pretty well with your high school math. To make it general, just divide the desired (matched) phase shift by 360, then multiply this by the length for one wavelength. So for 72 degr
Normally, the gain is for the far-field pattern, where E/H = 377 ohms, so the field patterns and the resulting gains are essentially identical. Contrary to popular imagination, there is only one kind
With orthogonal inverted Vees, there is still some coupling between the two because of the vertically polarized components. Even so, it's not hard to tune them for less then 2:1 SWR over the entire 8
Jerry, Try adding the feedline/pole to your model. When I did this, with a 40 foot vertical run of feedline plus a horizontal run of 62 feet at one foot above ground (and an assumed ideal choke balun
David, you have the right approach. Pardon me for saying it, but it is a good idea to consider anything by N0KHQ (and most of the other stuff on HamUniverse) with very cautious skepticism. He has som
Depending on how much the top wire slopes down and if the end then drops 10 feet straight down, the impedance could be around 50 ohms. With a 75 ohm cable, the 75 ohm SWR would be 1.5 and the impedan
Thanks Dennis. All those instruments are calibrated for a 50 ohm system, so the SWR they indicate on a 75 ohm cable isn't too representative of the mismatch at the antenna feedpoint. For example, the
In your case, resonance and 1:1 SWR are exactly the same thing. Resonance just means that the antenna impedance is purely resistive. Resonance isn't necessarily the point of highest gain: many antenn
But do you have to get Russian girls for Canadian men (as it says on your photo page) in order to keep your owl in residence? 73, Terry _______________________________________________ _______________