My first instinct when I see a long piece of two wire electrical lead (or zip cord) is to pull it apart and use the wire. Often the wire is nice and thick and good for HF dipoles.
However some people only pull some of the cord apart, using the remaining together section as a feedline.
This sounds a bit crude. The cord's impedance is a long way from 50 ohm. And there can be significant losses, particularly towards the upper end of the HF range.
You may need an antenna coupler between the transceiver and the feedline. But with any luck the types built in to some transceivers, only good for a limited impedance range, may suffice.
I've never used a zip cord dipole myself. But here's some experiences from others with them:
* K1TD QST article on zip cord antennas (pdf)
* KE8DI zip cord antenna
*Zip cord portable receiving antenna
However some people only pull some of the cord apart, using the remaining together section as a feedline.
This sounds a bit crude. The cord's impedance is a long way from 50 ohm. And there can be significant losses, particularly towards the upper end of the HF range.
You may need an antenna coupler between the transceiver and the feedline. But with any luck the types built in to some transceivers, only good for a limited impedance range, may suffice.
I've never used a zip cord dipole myself. But here's some experiences from others with them:
* K1TD QST article on zip cord antennas (pdf)
* KE8DI zip cord antenna
*Zip cord portable receiving antenna
If you've succeeded (or failed) with zip cord antennas please let me know in the comments below.
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I have used zip cord as an antenna and feed line with success on 80 to 20 meters. The best application was to split the line totally and place a spreader of 2 to 4 inches at the top, middle and bottom of the down lead(feedline) portion. In either case the lower end will then be attached to the matchbox with a short coax to the radio.
ReplyDeleteFor "all band" use I make the antenna section 88 feet or more total length. That means splitting 44 feet of zip cord before the feed line section. Make the feed line as long as needed. I usually split 100 feet totally then place the first spreader at the 44 foot point to start the feedline section. I make the feedline 40 feet long and have the 16 foot balance of the wire to extend the feedline if needed.
KG6HQD introduced me to this antenna on 20m via his SOTA videos. I think I got the dimensions from this article. I did one Aug 2019 with surplus WD-1A/TT military comms wire, it worked but too brittle to pack and carry repeatedly. The next one is made with 18Ga red black power cord, which is durable, but a little heavier than I like - I've killed two fishing poles with it. Now I've got some 22 gauge red black and am wanting to make another, lighter version. I've also done a 6m version that goes up on my balcony trellis for Field Day and VHF contests. No SWR issues (like 1.5:1 max) on any of these. Not sure the loss, but I make plenty of contacts including DX to VE & XE.
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