Here is some fresh data on my Vertical Dipole versus my Double Zepp. This was run last night and is typical of the reams of comparison data that I've accumulated on 40M. My methodology: I find a clear frequency, and after a couple of QRLs make a series of three CQ messages, spaced 5 seconds apart. Once the first antenna is checked, I change frequency by a few kHz and repeat the same series of CQs with the second antenna. I alternate which antenna I use first in case that might somehow skew the data. I create a printout of the RBN responses and determine which responses are common to both antennas and compare those reports. I also note which stations were received by just one antenna or the other. The data is remarkably consistent. Antennas: 180' Double Zepp, 30-35 feet above ground. This is a charmed antenna. I've been at this QTH for almost 20 years, and have tried countless antenna designs, and this is the best I've ever used, great even on 160M considering its length and height. I have a 40M inverted Vee with apex at 40' which rarely beats this antenna. This DZ is strung above the route for neighborhood underground utilities, and has a road and green belt in the foreground to the east. This may provide something of a counterpoise. I've won the Low Power NA Sprint and had numerous top five and top ten performances thanks to this antenna. The Vertical dipole is 25' long with 42" square hats on top and bottom. It is tied to a tree limb, and is pretty much buried in a stand of trees. It is fed with 300 ohm ladder line. Here is the comparison data compiled between 0303Z and 0305Z. Vertical dipole was the first antenna tested. Here are the results by receiving sites: Station Best Antenna dB Difference DR1A DZ 10 F5MUX VDp 7 V51YJ Equal 0 EA4TX VDp 2 WA7LNW DZ 5 N4ZR DZ 1 W4KKN DZ 6 KM3T DZ 3 K1TTT VDp 1 WZ7I Equal 0 NC7J DZ 2 K3MM VDp 4 NQ6N VDp 3 W3LPL DZ 1 NY3A VDp 9 KQ8M VDp 2 N0TA DZ 7 N7TR Equal 0 N6NC VDp 4 N6WIN VDp 1 K8ND VDp 2 Reverse Beacon Reports for only one antenna: DZ (1) W8WTS VDp (3) DL1EMY, WB2LSI, GW8IZR dB advantage over all common stations between antennas (the sum) is equal at 35 dB for each antenna! DX advantage: VDP had the advantage on 2 DX stations, DZ one and one was equal. Two of the three beacon stations reporting exclusively on the VDp were DX. The DZ was heard exclusively on only one reverse beacon, and it was stateside. These are completely unexpected results. I was hoping to find something that would be within a few S units of the DZ to use as a backup, but this antenna is more than its equal. Daytime results a quite similar, surprisingly. I haven't paid as close attention to them as 40M is a money band primarily at night, but during daylight periods of high absorption, the DZ seems to do 2-3 dB better. I was quite flummoxed after a rare but heavy rainstorm. The DZ was showing an average 5-6 dB advantage shortly after the storm. I surmised that somehow the wet ground was providing a better counterpoise for the DZ. Recall I mentioned that the VDp was nested in a stand of trees, that seemed to actually be the problem, as results normalized after two dry days. If there is one thing I can say with some authority, I know which antennas have worked well for me. I am limited to about 35' max height and 100' max length in my lot (one leg of the DZ goes into the lot of a very awesome and supportive neighbor!). My antenna effort is the sub optimization of some rather limited choices, when I find something this good, especially when it takes so little real estate, it is truly exciting. My mind now wanders to a multi-element array for 40M. I also wonder how I might apply this concept to a small 160M vertical. YMMV, but I've got abundant evidence that it works for me. Paul, K5AF In a message dated 9/22/2012 12:05:27 P.M. Central Daylight Time, [email protected] writes:
Well Tom, all I can say is that it works...... Here is more data.... The mast was a wood pole about 12 feet long and the feedline was buried, so there wouldn't be much radiation from them. There could be some from the base of the vertical to the dirt via the feedline, but that would be all that was possible. Well, there could be some while it is buried in the dirt, too, of course..... Not sure how much since I had a current balun close to the feedpoint. I do try to think of things like incidental radiation in my setup. Can't always do much about it, but I try. The point here was not modeling, it was experience..... Of which I have considerable. I have used these antennas alot (half wave verticals) during my 52 years. They have never disappointed from an actual performance point of view. I will say, however, that they seemed to work better from Hawaii and my house was VERY close to the sea there almost 360 degrees. But ANY antenna seems to work better when surrounded by sea water, so that is kind of a given. If we are talking a modelling contest, then I haven't got a clue with all the variables. I can just answer someone who asks if I used one..... The answer is no.... I have used many of them and they ALL worked well enough to make me want to keep them. That is about a good as I can say for any antenna :) :) BUT I do hear you, which is why I said what I did about the installation..... All of it may well apply to my success with the antenna. Mike AB7ZU Kuhi no ka lima, hele no ka maka On Sep 22, 2012, at 5:54, "Tom W8JI" <[email protected]> wrote: >> A ringo ranger is a vertical half wave using "end feed" and they work >> great. I prefer end feeding, using hte method of the ringo (which is >> easy to scale to other bands). I purchased the 10 meter version some >> years back and built ones for all bands to 20 meters by scaling the >> end-feed arrangement. > > When we end-feed a vertical like that, without radials, the system can have as much radiating current on the mast and feedline as the vertical itself has. This can do all sorts of things to the pattern and gain, because the feedline and mast become a major part of the actual antenna. > > There is a basic electrical rule that cannot be broken. In order to force current up into the vertical at the feedpoint, an EQUAL current has to flow back down into the coax shield, the mast, radials, or something else. > > We are kidding ourselves if we look at an end-fed antenna without a ground system and proper feed isolation and assume only the vertical is the radiator. > > This is why, later in the Ringo's life, Cushcraft added a kit that added radials to the Ringo. > > 73 Tom _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
