Russian Monopole Mystery!
Several years ago I was having a conversation on 20 meters with a Ham in the northeastern part of the country. We were discussing the merits of vertical antennas. We discussed phase arrays, trapped verticals, half wave verticals, short verticals, loaded verticals, and full wave verticals. One of the antennas that popped up was about a curious multi-band monopole antenna used by the Russians. The Ham said he would send the copy of the information he had on the antenna so I could examine it.
Surprising Find!
Two weeks later, I received the large envelope containing the information on this particular antenna. After some time ( I don’t read Russian) I was able to figure out what was in the envelope and run it through the simulation program, A06.5. The results I obtained by analyzing this antenna were more than a little bit surprising. First, I noticed is that it would not operate below 4.5 MHz and the pattern was primarily high angles with all the energy being concentrated above 50 degrees.
Figure 1 shows the shape of the vertical pattern at 10.1 MHz. As you can see, between 120 degrees and 60 degrees is where most of the radiated energy is concentrated, and a high gain at that. The azimuth pattern of this antenna is almost a circle, but is very slightly oval, with some compression at the 0 and 180 degrees bearings.
This can be seen in Figure 2.
The three-dimensional pattern can be seen in Figure 3. These patterns remained constant from 4.5 MHz to 30 MHz, with most of the radiated signal concentrated to the vertical plane. There was some slight squeezing of the pattern as the frequency was increased to 30 MHz.
Why Just Upwards?
With all of this information in hand I was unable to figure out why this antenna radiated nearly all of the signal in a vertical cone. It made no sense to me as a Ham, to make a vertical antenna with a high angle of radiation. I wondered about this for quite some time, but was unable to come up with an acceptable answer for this particular antenna to have this type of radiation pattern. It just made no logical sense. Why would anybody want a vertical antenna that only radiated its signal upward?-and also to cover the frequency range that it covered, which are prime DX frequencies?
Possible Clue
It was several years later that I found a very plausible answer for the construction of this particular type of antenna. I was at the library and happened to pick up a magazine devoted to the aerospace industry. In one of the articles, I noticed it mentioned the Russians used single side band to communicate with their space station. It also said that they operated in the range from 10 MHz to somewhere in the range of 30 MHz. Also, a new antenna was being used to accomplish communications between their space station and ground.
I wondered if this could be this same mysterious antenna. It certainly fit the description I was reading. Also that mysterious antenna covered up to approximately 138 MHz, and possibly even higher in frequency. The article stated its subject antenna also covered to approximately 138 MHz. Further speculation about this particular antenna reminded me the Russian army used the same frequency range in the 30 to 60 MHz range that we also used . When I was stationed in Germany, I had heard the Russian military operating on the very same frequencies we used. It further mentioned another version of this antenna that even went higher in frequency-another coincidence?
Figure 4 is an illustration of the antenna as interpreted from the magazines article.
The first antenna, as described in the magazine, consisted of a 6 in. (15.42cm) diameter mast, 43 ft. (13.072m) tall which had 4 wires at 90 degrees around the mast, spaced 4 ft. (1.216 m) out from the mast. These 4 wires lead up the mast for 23 feet (6.992m), then went in two ft. (.608 m) toward the mast, to 4 standoff insulators and continued up to the top of the mast while remaining spaced 2 ft. (.608 m.) out from the mast. There all the wires were connected to the mast. The mast was grounded at the bottom. Because this antenna covers such an extremely wide frequency range, some sort of antenna tuning system has to be used. Impedance variations go from less than one ohm at the bottom of the frequency range to several thousand ohms at the high end of the range.
Looking at this antenna in the HF range, having all the radiation in a vertical cone made sense, that is, if you wanted to transmit to a space station. Also, being able to use the same antenna in the VHF range would be an advantage for the Russian military. HF communications between ground stations and the space station would enable communications concerning ground movement of a military force very easy. It would also allow the ground stations to communicate with each other at the same time, therefore allowing coordination between ground forces. It is plausible this particular antenna was used for these purposes but once again, it is only speculation, but, the specifications for this antenna strongly suggest it is a very good candidate for this type of communications usage.
Unless someone more familiar with the use of this antenna tells us, we can only guess how this antenna was used. But, my curiosity is piqued and I would certainly like to find out more. The other version of this antenna will be discussed in detail as the subject of a future article.
As mentioned in last month’s issue, there would be another part about the second mystery monopole antenna I received information on some years ago and have followed with interest since. Again, I want to say that I have no more information on this antenna nor can I vouch for the actual usage or nationality of origin of this antenna. So all I can say is it is an interesting antenna and believe its origins are from Russia. Don’t bother asking for any more information, as what you see is what I got.
Constructions
In Figure M-1, the construction of this antenna can be seen and it is fairly simple. There is a 60 foot (18.24m) mast with 4 separate 20-foot (6.08m) arms holding the four conductors that go to the top. At the bottom are four conductors spaced 1 foot (.304m) from the mast and then tied together at the feed point. The four arms are insulated from the mast and are conductors. These arms are fed by the four conductors tied together at the base. All of the four main conductors that run up from the arms are tied together at the top. The base of the mast is grounded. A base mounted tuner is required to match the antenna through the entire frequency range.
Pudgy Figure 8 Pattern
The frequency range of this antenna was supposed to be from 200 kHz. to 4.4 MHz and the pattern does have some interesting variations over this frequency range. At 4.4 MHz, the azimuth pattern is a very slight oval and at 200 kHz, it is a pudgy figure 8. Figures M-2 and M-3 show this.
Perfect to Pinched Dome
The vertical pattern varies from a perfect dome at 4.4 MHz to a dome that has been pinched inward on the Y-Axis at ground level. This pinching effect continues up for several degrees from ground level, then gradually goes away and the pattern smoothes up to a dome-like at 4.4 MHz. Figure M-4 is the pattern at 200 kHz.
What id Purpose?
Now looking at these patterns, I have wondered as to the purpose this antenna. Quite possibly some sort of research in the long wave bands? I do not know. The pattern stays the same up to 4.4MHz, then starts to distort in some really weird manner as the frequency increases. Most of these distortions render the antenna useless for what we would call “normal amateur” communications as they are a very high angle of radiation for the most part. Even if you cut the dimensions in half, the low end cutoff frequency increases to 10 MHz and the antenna is useful up to 29 MHz, but with a high angle of radiation.
Tell Us For Sure!
This is another real mystery antenna, as far as I am concerned, and the answers to the many questions may remain unanswered. I sincerely hope someone will pop up and tell us some more about the two monopoles discussed here.
Originally posted on the AntennaX Online Magazine by Richard Morrow, K5CNF
Last Updated : 25th April 2024