Counterpoise 2.0: Another Attempt

During Scout Camp last year, I experimented with adding a counterpoise to my handitalkie.

The results were not good.

With the Chicago Marathon on my calendar, I decided to revisit the experiment.

Reconsidering the Problem

The Yaesu VX-8DR is a great little radio with one drawback. As you can see in the picture below, the SMA post on the left has a foot that spreads out slightly. That design makes it difficult to add things to the circuit like a counterpoise or some other half-baked idea.

IMG_7640-compressor

I suspect the spreading foot kept my original counterpoise from making a good connection.

As you can see, an eye loop will not connect in a flush manner.

IMG_7643-compressor

Worse is the fact that the stock antenna will not completely seat without the rubber seal designed to fill a gap between the antenna and the radio chassis.

This photo shows the antenna as far down as it will connect, leaving at least 1/4-inch of space.

IMG_7646-compressor

Adding the rubber seal doesn’t improve the situation.

IMG_7650-compressor

Possible Solution

When I returned the rubber seal to its normal position and screw on the antenna, I decided to bend the eye loop about 45-degrees.

IMG_7653-compressor

As you can see, the antenna is flush with the chassis and the eye loop appears to make good connection with the antenna post. If there is a good connection, the counterpoise will be part of the antenna circuit. It is possible that I can have a vertical, off-center-fed dipole on VHF. On UHF, the counterpoise will add to the ground plane.

Either way, the counterpoise should improve antenna efficiency quite a bit.

Making the Counterpoise

Each of my counterpoise wires will be a quarter wave in length.

  • For 146.52 MHz, the radial length should be 19.2 inches
  • For 446.0 MHz, the radial length should be 6.3 inches

Once you cut the wire to the appropriate length (I used AWG #14 wire), solder a Number 10 Eye Loop onto one end of each counterpoise.

To make things easy, I used red wire for VHF.

IMG_7656-compressor

And black wire for UHF.

IMG_7658-compressor

Here is the final assembly using the red VHF counterpoise.

IMG_7662-compressor
Preliminary Results

In my preliminary test, I wanted to see how well the radio performed with the new counterpoise.

With my wife at home, I rode my bike until we were far enough apart that my radio just broke squelch. I was about 1.5 miles downrange.

Nothing.

Zip. Zero. Zilch.

Nada.

Move around. Held the radio higher.

Didn’t matter.

Conclusion

Hand-held radios are not efficient things to begin with. A radio hanging on an operator’s belt can suffer a reduction in signal strength by as much as 20 dB when compared to a radio held at face level. When you run the math, it’s not uncommon for a “five watt radio” to have effective radiated power of a mere 15 milliwatts!

The Counterpoise trick as a way to improve the efficiency of a hand-held radio doesn’t appear to do anything but raise SWR.

As Mythbusters would say…

pablo-341

You may also like...

4 Responses

  1. I don’t think that you describe the test properly. What was the control mechanism? You just rode a bike until the squelch was barely able to be broken and THEN set the counterpoise?

    What antennae did you try? Just the rubber duck that came with the radio? Did you try other antennas for reference?

    There’s not enough information to just blow it off as a “myth busted”.

    I have used a “tiger tail” with a telescopic antenna and noted an increase in signal reception and improved signal into various repeaters. Granted this was years ago. I had an HTX-202 with an Anli antenna and used it with and without the counterpoise and noted a better signal with than without.

    Of course different results from different radios and antennas so your mileage may vary.

    • No, I didn’t and I’m getting clobbered over on Facebook for it. I plan to recreate the test using an analyzer and mark it out a little more academically for everyone.

  2. Craig says:

    I have made a 1/4 wave wire and it did increase my signal using a 1/4 radiator. With and with out same spot , same height.

    Where are you getting -20db?

    In my case I did two different ht’s both had a full 1/4 wave antennas.
    How did your measure standing waves?

    One test I did was on top of a mountain top with a line of sight nearly contact. Also facing the direction that i wanted to communicate in.

  3. a ham says:

    What you need to do (and I should do but I don’t know where to post the results) is use an “antenna analyzer” (or, in my case, a MiniVNA Pro SWR or Return Loss mode), screw your antenna on to it, and record your measurements without and with the tail. Your radio may have more or less metal and plastic but as long as you’re not holding it at the time it won’t make a difference. (You DO know the radio is already using YOU as a counterpoise, right?)

    Admittedly, using my MiniVNA Pro gives me an advantage because of the Bluetooth as I can stand away from it and capture the measurements and then hold it (by the connector, probably) to simulate the “human counterpoise”. Even though the case is plastic, the board seems to be resistant to the effects of objects like hands being near it.