"Tigertail" HT Counterpoise
A great way to increase signal strength when using a portable rig.
by Chad Rudolph, W1CAR
The idea here was inspired by many other amateurs including Ed KE4SKY and Virginia RACES
These parts can all be found at Wal Mart or any hardware store. I found them in my garage.
UPDATE: Another idea inspired by Ed Harris KE4SKY: For dual-band HTs, try using 2-wire zip cord...of a small gauge, like 18 or even 24. Speaker wire works fine. Cut the wire at the normal 2 meter 1/4 wavelength for the 2 meter side of the counterpoise. Follow the rest of the instructions to finish the single-band Tigertail listed below. Once finished, carefully mark 6.5" down from the HT antenna connection point and unzip and cut the cord to that length, making a 1/4 wave counterpoise for the 440 band with the shorter of the two wires of the zip cord. Install heat shrink at the split point to keep the zip cord from coming further unzipped. -Chad W1CAR 7/24/04 |
Theory: (KE4SKY's explanation here) The idea is that an HT using a "rubber duck" has -5db gain compared to a quarter wave antenna that is held at shoulder height. Speaking in terms of effective radiated power, a 5 watt HT with rubber duck antenna held at shoulder height is actually only radiating 1.5 watts on key-down. The stock antenna is a horrible radiator, and it lacks a counterpoise or a ground plane to keep the RF from coupling to your body. Similar to using a 1/4 wave mobile mag-mount and not mounting it to a metal surface. By using a Tiger Tail counterpoise, you give your HT a missing lower quarter wave and along with a quality aftermarket antenna (flexible 1/4 wave or telescoping 1/2 wave) you succeed in creating a center-fed half-wave vertical dipole, giving the HT much much more effective radiated power. The Tiger Tail can be left to dangle, but is directional and the radiation pattern can pointed in the direction of the station you are attempting to contact for better results. I've seen these talked about many places on the internet, and most say to use a battery clip to connect the Tiger Tail to the BNC connector of the HT. I have yet to see a picture of one, however...and that left me with a bit of uncertainty about the construction itself and its inherent durability. So instead if using a battery clip, I decided to use the hose clamp because of availability, ease of use, and the ability to tighten it to the BNC to make sure one won't loose it in the field. This is also a good idea if you have several different antennas for your rig, so you can temporarily or even permanently attach the Tiger Tail to each antenna. Try it out and see the difference for yourself. Suggestions for aftermarket BNC HT antennas: Hamstick Dual Band Rubber Duck Antenna
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Copyright 2004 W1CAR Chad Rudolph 147300.com