I just looked at my XM240 in EZNEC at 1.8 MHz and the gain, straight up with the source at the antenna, didn't look too bad, but when I figured in the line loss for my RG213, the line loss was 34 dB.
I just had an interesting antenna experience. K4JRB mentioned that his XM240 works as well as his dipole L (I think maybe that is an inverted L?). Anyway, knowing that an antenna this short can't be
He has to have something wrong in that stack. K4XS had a good guess. Assuming flat ground, on 20 meters the only time that monobander should only be better than the stack is for signals arriving at g
Was it this one? 2x3 stacked SteppIRs http://www.k9ltn.com/ Jerry _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@cont
"..I wonder if he had the phasing wrong?! Again - the difference is HEIGHT - not gain! ".... "...Modeling will show at times 10 - 20 db difference - a vast amount more than the difference in gain bet
I notice the model uses 2 inch diameter elements throught out, which can't be correct. What it the taper schedule for the elements? Jerry. K4SAV _______________________________________________ ______
How high is this antenna when you are measuring the SWR? Sounds about right for an XM240 at about 15 to 20 ft high, or maybe at 30 ft high if it's over a set of radials. Your analyzer could also be l
"I have never understood why the 40-2CD reflector is grounded and the XM240 is not........basically they are the same antenna...." I'm not really sure either, but I'm willing to take a guess. When th
"EZNEC analysis of the antennas shows no difference with the reflector grounded or not." I should have added some details to that statement, so that I don't mislead anyone. It's true that the XM240 s
A solution using some kind of cheap clamp with a screw, is more expensive and requires more skill to install. If you use some kind of clamp, you have to apply an antioxidant and seal it from moisture
Definitely sounds overloaded. I have an HDX555 with a 4 element SteppIR 2 ft above the top of the tower, and an XM240 9 feet above that, and a 20 ft mast. That's a total of 16.4 sq ft (of antenna plu
"...can anyone tell me how to plot the vertical pattern in EZNEC? ".... You select the plot type as "elevation" and specify the azimuth direction you want , usually 0 degrees. Hit the "FF plot" butto
EZNEC does display the pattern in free space, but it also gives the pattern over ground (of any characteristics) at any height, but only for flat ground. EZNEC cannot handle arbitrary terrains. For t
I haven't tried to calculate RF exposure data this way but you can get near field data from EZNEC. Maybe just use a generic 3 element 10 meter yagi. Something like 0 -8.39 50 0 8.39 50 1 11 6.88 -8 5
A shield over a ground wire will change the resonant frequency of the wire. (More change if you have a dielectric in between.) Depending upon what your problem frequencies are, you may make matters b
"What if you use two different gauges of wife (say #14 and #18)..." I'm sorry, that's not legal. -- _______________________________________________ _______________________________________________ Tow
....I am also concerned about wind loading with the tower vertical and the mast's ability to handle that. ".... The software obtained from the link below, shows that the ratings of your mast will be
I would answer your question, but I couldn't figure out what it was, so I will just give you some information. A ground rod for a dipole with a polyphaser will probably be OK to protect against induc
Wow! Very interesting info on your XM240 balun, Steve. Please describe your tower, height, and what you have on it at what height. I would like to model this and see what the model tells me about the
I have seen two posts now claiming that an inverted vee works better than a vertical for receiving on 160 meters for both DX and local (at least for the persons posting). I'm not disputing these clai