With respect to the claims below by Gap, the trick is that the "other" antenna descriptions are not complete, either as to their size or configuration. For instance, a base loaded 6 foot whip resonan
Unfortunately, the Cushcraft 40 will detune the TH7DXX on 15m at any spacing you can manage on the same mast. There have been numerous instances locally of "pulling" any 15 meter antenna's tuning by
We tried that around here and the interaction was worse. At right angles the boom is in play with the reflector acting as end-loading. In addition to the Force 12 models, the Optibeam 2-40 and 4-40 a
There is no "must be". While the 40m will probably benefit more from being on top, the weight of the antennas and the material your mast is made of may determine which antenna goes high. 73, Guy, K2A
If the low band antenna is heavy enough or has high enough wind load so that the mast is not rated to carry it at the top, one would put it at the bottom to keep from destroying the mast. Otherwise i
You can use an MFJ269x analyzer or equivalent. Put a 50 ohm non-reactive resistor in parallel with the trap and use the frequency button to scan it. Look for the zero reactance points. This will be f
The intent was to reduce the amount of circulating current in the trap at the operating frequencies. However, this also changes the placement of the trap, the trap component values and the wire lengt
Hi Andy, dBi is relative to an "isotropic" antenna in free space. If you place the isotropic antenna in free space relative to an unvarying transmitted signal and get 50uv/50ohms of received signal a
Andy, Terry... "Check out this web page http://www.djmelectronics.com/articles/emc-antenna-parameters-p3.html which has a detailed discussion of antenna factor. Note that their definition of antenna
A low horizontal loop is almost entirely a high angle radiator. At the heights you are talking about, miscellaneous ground factors can make it lossy and a poor performer. Speaking anecdotally, a ham
Changes in temperature and air pressure will always cause ingress of water vapor, which will condense. The trick is to leave water a way to leave. Don't bother to try and seal them. It may work tempo
This is actually a fair amount of work to come up with 6 models and make sure they are "clean" at the frequency used and represent specific components. Also you will find that generalities do not alw
Since the run is about 30 feet, make it 33' or 32' if it's not bare. And use up the extra length by not making square turns anywhere. Don't put sharp bends in the wire if you can avoid it. You *may*
We have lost a standard. From the email today... -- Folks: This is the saddest announcement we have had to make: It was discovered this morning that LB Cebik, W4RNL had passed away. He was a friend t
You are talking about substituting discrete wires to create the effect of a loop made of 10 or 100 mm pipe. Just do that in the model and see what happens. 73, Guy. Hello Guys, I have a model for loo
A Force12 C3SS would outperform the G5RV without the loss of traps. Since 25' is nearly a half-wave on 20m you will be surprised how well a good tribander will do at that height. 73, Guy. I am curren
In order for me to see what is going on, I need to run the director configuration with AO Pro, which is the only tool that will allow me to watch what is changing according to a formulaic progression
If I am understanding the 259B manual correctly the "loss" is actually "return loss" and measures the ratio of energy sent to reflected energy received in dB. This means different things is different
At 160 meters the antenna is an 1/8 wave and need base inductive loading. On 80 meters it's at or near 1/4 wave resonance. On 40 meters it's an end-fed half wave, with a *very* high Z feed. It is lik
Second what Gary said. Further, from my experience in model vs. actual, the one thing I *don't* worry about is the exact presented impedance. The model will tell you things to try, things to avoid, b