On this outing I did more listening than transmitting and spent most of the time monitoring 40 metres. I also had the HT monitoring 146.500 Mhz. Whilst listening I thought I'd do a little antenna experimenting just with the gear I had on hand. The main purpose of this was to improve my chances of reliable 2m contacts when opreating portable or SOTA summits but without having to carry a pole or a bulky beam.
On a few occasions when operating portable, I have used a dual-band ground independent mobile whip hung by it's tip from an overhead tree with a short run of coax to the radio. This has worked quite well and is a big improvement on using a standard rubber ducky antenna screwed directly into a HT or the FT-817ND. The main disadvantage can be the length of the whip. It can be a nuisance or even a hazard to carry through dense bush tracks. This is also the reason I don't carry a squid pole.
The ingredients of this antenna are simple and I had all on hand without any pre-planning:
- Four lengths of wire, roughly ¼ wavelength
- A lightweight mobile base and lead assembly, 5 metres long terminated with a BNC
- BNC to PL259 adaptor
- 2 wooden sticks
- a roll of electrical tape
- OEM FT-817 Rubber Ducky antenna
Putting these items together was crude but effective. Firstly strip the insulation from one end of the four pieces of wire. Strip a good 3cm back and twist the wires together and then wrap around the theaded antenna base, using the lock ring and nut to secure. Next get the two sticks and tape them together to form a cross. Then tape the ends of the wire ground plane you have just made to the sticks and adjust so they hang at about a 45 degree angle from the base. Connect the BNC/PL259 adaptor to the whip and then to the base. Connect the BNC at the end of the feed to the radio, tape the string to the top of the whip and throw the other end over a nearby overhead tree limb and adjust for maximum allowable height.
Hey Presto! Instant emergency antenna for VHF and UHF. This works so much more efficiently than mounting the whip directly to the radio which is cumbersome at the best of times. Indicated SWR was very acceptable across the 2 metre band and I could key up a number of repeaters easily that the HT was struggling to reach. Next time I do this, I will experiment a little more with the length of the ground plane wires as well as the 70cm band. I will also screw the longer stub on the OEM FT-817 whip and give the 6 metre band a try.