I sent Walt an EZNEC model of a circular halo for 6m with a hairpin match. If anyone else is interested, respond off list. 73, Terry N6RY _______________________________________________ Antennaware m
The approach of using a pair of helically wound monopoles to create a balanced dipole should work fine. Of course, when you shrink a 66 foot long dipole for 40m down to 8 feet long, you are definitel
Is it possible you are looking at the elevation pattern at 45 degrees off of boresight? Say at 0 or 90 degrees azimuth? The models that come with EZNEC at oriented with line of the elements parallel
This is easy to model in EZNEC. I used the original 29x14 foot dimensions from K6SE's article in the July 2000 QST with two point-fed pennants with their points separated by 1 foot. The pattern and g
Of course, SteppIR also has a loading coil that gives you coverage across all of 80m and 60m with the BigIR vertical. The efficiency might suffer a little (maybe 1-3 dB) compared to the higher bands
I created a model of a 2-el yagi on 20m with 6' spacing and the gain in free space is 6.71 dBi (4.56 dBd). F/B is 17 dB. This is with the parasitic element tuned as a director. The feed Z is 22 ohms,
Paul, It's usually much easier and often more accurate to use the built-in transmission line capability in EZNEC for modeling feed lines. The exception is for cases, such as stubs in collinears or St
It's no problem modeling the stub in EZNEC using the built-in "virtual" transmission line feature. From the Radioworks description, it appears that it's a shorted 1/4 wl stub on 40m, which looks like
Thanks for the modeling data, Paul. Not surprisingly, the horizontal loop (1 wl circumference) has to be higher than a dipole to give equal or greater gain at angles 50 degrees or less (since the loo
When I overlay the elevation plot for a 4 square array on top of the plot of single vertical, the plot for the single vertical is ~5 dB down from the 4 sq. I tried setting the reference gain for the
I tried Gary's approach of using an external graphic program with the simple "Paint" program that is included in Win XP. From the 2D plot window in EZNEC, I used Edit - Copy Plot, then pasted the plo
The demo version of EZNEC, with its limit of 20 segments, won't be too accurate for this array. At a minimum, you should use 10 segments per half-wavelength, so a 3-element array needs 30 segments ju
The unloaded Q of the inductor should have a very minor effect on the bandwidth and efficiency of WX7G's 67 foot antenna on 160m. The series resistance of a 70uH coil with Q=400 is only about 2 ohms.
Andrew, It seems like you could put a resistor of the design "-R" value in series with the input of the NIC and check for a short circuit. If you're thinking of using this to cancel the resistive loa
John, Probably the best approach is a 4:1 "current" balun, which tends to float the connection to the twinlead and should reduce current on the outside of the shield of the 75 ohm coax. However, in t
Gedas, I think youve gotten some great advice on this antenna, but I think this is better as a thought experiment than a real antenna. Ive attached my EZNEC model for your consideration (which will p
I suspect youll be just as close by trusting the model. Making measurements of antennas in the wild, especially one with so many lossy elements, is likely to involve a lot of approximations, too. Cur
Dave, In general, using real/Mininec ground will give you slightly optimistic gain numbers, especially with horizontal conductors under 1/4 wavelength above ground. This is because for impedance calc
Hi Greg, No secrets here! Have you considered a double extended Zepp? If you dont need an out of phase pattern with a broadside null, its essentially the same gain as a collinear. Of course, since th