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Modeling a single or 2 element quad and a dipole and 2 element yagi in free space shows the "why" of the difference. In the vertical plane bisecting the elements, a quad element squeezes the vertical
Since you didn't mention switching each element, what occurs to me, given your two dips in resonance, is that you have in effect a pair of two element beams, a reflector beam on the low end and a dir
The pattern for either band resembles a water lily, many small lobes at various elevations around the entire compass, with more power at higher angles. Low SWR on 24 and 28 may indicate loss in the s
I've gotten to the point where I model ALL conductors in the vicinity, including coax shields, towers and metallic guys, with appropriate lumped loads where baluns are used, etc. This would include a
What I have never seen documented is actual measurements of far-field sky-wave changing with numbers of radials, along with the corresponding measurements at the ground. Sky-wave has always been by i
Well, good. Any idea where I might be able to dig up that document? Or where to start? I remember listening to WHO in Columbus, Ohio as an eleven-year old with a 5 tube radio after everyone else asle
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*