Author: "Jim Miller Waco Texas WB5OXQ" <wb5oxq_1@grandecom.net>
Date: Sun, 15 Jan 2012 18:31:20 -0600
I must move my 40 and 75 dipoles due to rfi in the house that I cannot resolve. I am thinking about 1 dipole fed with ladder line or window line. I have 2 possable support points. 1 pair is 126' from
I use a 1:1 balun mounted on the wall outside the radio room and bring a short coax line (about 10 feet) into the shack to an ATU. I didn't want to bring open wire into the shack without preparation
My low freq antennas evolved along the same lines (no pun intended). Ultimately, you just need to try it. The "dipole" can be almost any length, and need not be resonant. Whatever the lowest freq you
John: I have a set up similar to your dimensions with the middle half of the ant passing over the roof. I use Radio Works classic North Carolinia 80 M - 10M Windom Ant about 133' long, 67% offset. Th
Actually this setup is covered in this month's QST "The Doctor Is In" column with a couple of references to older QST articles. A center fed dipole with open wire or ladder line is a very good multi
Hi Ken et al, I had mis-givings here about feeding my 160-meter half-wave inverted "V" dipole (50' at the apex) with foam-type 300-ohm TV twin-lead--and using it on all bands from 160- to 10-meters--
My View: If it works, go with it! Although 300 ohm twin lead or foam filled 300 ohm twin lead is limited in its power handling capability the two conductors in such close proximity make it less susce
Hi Roger - Regarding the 160m quarterwave slopers. Granted there may only be a few db F/B ratio with a qws but wouldn't you rather radiate 3KW than 1.5KW if it was just for the price of a bit of wire
Antennas like this do not have to be precisely tuned. 100% correct. 100 feet will give essentially the same performance as 135, 130, or 125 feet, just squirt the RF in different directions. By "same
Yeah, sort of. But any antenna that looks like a very high impedance at the feedpoint is likely to result in a difficult to match impedance at the TX end of the line. SO -- a "good" length is one tha
I see it differently. When going significantly below a half wave, you are eliminating a significant portion of the high current portion of the radiator. The highest radiation currents flow in the cen
Ken, EZNEC predicts that a 100ft dipole used on 80m is only a fraction of a dB less efficient than a full half-wave; the feedpoint current only has to increase by about 19% to "compensate for the mis
Steve, The issue is not about I^2R losses and feedline cannot compensate for missing antenna wire. It's the antenna wire that radiates, not a properly balanced feedline. How do you "increase the feed
A shorter wire means the feedpoint impedance (resistive part) gets lower, so for the same power, you have more current. That comes with the inconvenience of a bigger reactive part, which you need to
You are trying to tell me that if I had an excellent matching network, I could use a 2m dipole on 80m and it would be just as effective? Sorry, I think you are confusing feed and matching losses and
What does "effective" mean? If you define it as "getting RF power at the feedpoint launched into space", ANY size lossless antenna works pretty much the same. That are differences in the spatial dist
That's about ten decades of research reading to catch up on -- starting with short Marconi base-fed vertical radiators, then moving on to the shortened, but optimized "T" used at 1BCG for the transa
I've got an 88ft that will load but with difficulty on 80m and it is mostly a cloudwarmer on that band. I now use it on 80 and 160 by using the windowline feed as a vertical and the 88ft wire as a lo
Regarding "dipoles" there are a number of points that have been well presented: 1. If the antenna is to be used for multiple bands, keep it nonresonant to avoid feed point impedance extremes. 2. Shor