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Wires & PliersVariations on a "Petlowany"William Caldwell Sr., WA8ABE
This was my experience with the "Petlowany" antenna. First I found the reason the antenna went into antiquity was the difficulty in winding it. After winding several by hand, I decided to make a form to hold the windings. It doesn't matter whether the antenna is round, square, or octagonal other than some difference in wire length. As long as the windings are symmetrical and spaced evenly, the performance was the same. Size of wire had no effect on the perfomance other than power limitations with smaller sizes. I have made more than a dozen of these antennas, all the way from 2 Meters to 160 Meters, and every one of them had the same characteristics. If the wire is measured for one quarter- wave plus a little, spaced evenly and symmetrically, the impedance will be near 52 Ohms. I started by making square forms using 1/2" X 3/4" X 20" wood and forming a cross. I then drilled a 1/8" hole in the center, and drilled a 1/8" hole every 1/4". After drilling all the holes, I cut 1/8" dowel into pieces 1 1/4" long. I placed them in the holes and drove them into place with a hammer. If they were loose, I glued them in. I made a second form with the cross being 24" in total diameter to accommodate the longer wire for 160 Meters. Starting at the center hole and proceeding to the end of the wire, stretching the wire as I went, made for a very sturdy antenna. The connections are simple. I soldered the center conductor to the center end of the wire and I either left the shield alone or hooked it up to ground. The ground can come by way of the transmitter end. The first antenna was wound with #26 telephone wire and was used on receive only, or with very low power. I used the smaller wire because it was easier to use and keep tight. I tested this antenna with an MFJ-259 antenna analyzer and with six feet of RG58U coax to test in the shack. I compared receiver "S" units with an inverted "Vee" with the apex at 35 feet. On 160 Meters, the inverted "Vee" brought a skimpy S-1, but the spiral antenna, at 20 feet high read a peak S3-4 on SSB.
After using these antennas, my mind wandered to mobile use. Since the mobile antennas have only 12 or so Ohms, maybe this "Petlowany" could be used for a counterpoise. I made a square "Petlowany" wound for 4 MHz and attached it to the ground of the mobile antenna base, laid it on the shelf of the rear window, and went mobiling to a hamfest 60 miles away. (The mobile antenna is an old Hustler center loaded which was for 40 Meters originally, but I rewound the coil for 15 Meters.) I turned the radio on, and the reading was flat at 21.360. The band was pretty busy for early morning. Stations were on from Yugoslovia, Germany and many other European countries. My first contact was with W4ML, a special event station in Virginia and I received a 5-9 report. Next was YU4EBL, another special event station and another 5-9 report with "potent signal" added to it. A contest station in Germany, DK5EZ, was next, and another 5-9 report with "great mobile signal" added. I've worked mobile for many years, but never got an answer almost every time I put my call in, especially in the middle of a pile-up. Because the "Petlowany" counterpoise brought the mobile antenna impedance to 50 Ohms, all the power was in the antenna. I removed the counterpoise and the answers stopped. So, good enough for me, the "Petlowany" was a superior type of antenna. When some enterprising person gets it all together, this will be the next century's antenna, considering the widest antenna, for 160 Meters was only 24" wide. I can't explain the characteristics of the antenna, nor the formulas for using it, but we've had many discussions in the club newsletter about it. I have given demonstrations of it at the meetings, and several of the guys are making their own, with good results.
I'm still winding and experimenting, and will keep readers informed of any new developments. Photos show my variation of the Petlowany antennas mounted vertically and horizontally for testing on various bands.
Good results were obtained by laying the antenna on the package shelf of the car. |
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Last
March, a friend showed me an article from Worldradio, about a new type
of antenna. He asked if this were possible, and could it work. Since it
was such a radical difference from antennas as we know them, and since
I have been around Amateur Radio since the early thirties, I agreed to
experiment with it and to give a report to the local club.
For
the second antenna, I used #14 house wiring with the insulation removed.
At lower frequencies this antenna would not tune when in a vertical position,
so I had to mount it horizontally. At higher frequencies, the orientation
didn't seem to matter, however the impedance did go up while in the horizontal
position. After using the #14 wire, and having difficulty maintaining
parallel windings, I tried three #26 wires, twisted slightly and in parallel
and found it much easier to work with. Three #26 wires in parallel allows
the use of 100 watts.
Thanks
to Bill Petlowany's father-in-law for being 100 years ahead of his time,
to Bill for writing the article, and to Worldradio for printing the article.
Not many magazines print articles without complicated math to confuse
the masses. It was just a good down-to-earth article and with just enough
information to make it interesting.