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.
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.
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.
Adding the rubber seal doesn’t improve the situation.
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.
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.
And black wire for UHF.
Here is the final assembly using the red VHF counterpoise.
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.
Zip. Zero. Zilch.
Move around. Held the radio higher.
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…