G5RV Antenna Construction
Construction your own antenna is not all that difficult and certainly a lot less cost than buying one that will deteriorate the same way in the weather.
Here are some interesting facts about common antennas:
A 3el full sized perfectly matched yagi will give you about 6.5 db forward gain
A 2el full sized perfectly matched yagi will give you about 4.5 db forward gain
A 2 or 3El trapped Yagi will give you about 0.5 to 1.0 db gain less than a full sized equivalent.
A 2el full sized perfectly matched yagi with folded elements. (Hexbeam, Spider Beam, Moxon and others of their ilk will give you about 4.0 db forward gain.
A perfectly matched resonant dipole will give you 0.0 db gain
A trapped dipole will give you a 0.5 to 1.0 db trap loss compared with standard dipole.
G5RV, OCF and other weird and wonderful antennas are a compromise to gain bands. You gain with wide frequency coverage but you lose dbs compared to a standard dipole.
A quarter wave vertical, perfectly matched with 128 radials will give you zero db gain
Reduce the radial numbers, insert traps, reduce the length with helical windings and you lose valuable db.
With antennas – you don’t get something for nothing. Yes, you will have contacts with any antenna. The more compromised the antenna is, the less contacts you will have with it.
The case of the commercial $195.00 G5RV wire antenna kit
Yes, it will work just fine. Not as well as a full sized dipole on any given band but it will work well. No marketers of these snake oil antennas have ever managed to get any gain out of them. They are less efficient than a full sized dipole. Simple fact. On the other hand they will allow you to make contacts on 80M, 40M and other bands.
Shell out $195 or build one? They both work the same!!!!!! If you scrounge around in junk sales or your mates you may find 105 feet of wire. Any wire, Plastic covered, bare wire even old transformer wire. But “It stretches” I hear you moan. Simply tie 60 or 70 feet around a trailer hitch and the other end to a tree and put slow tension on it. You now have hard drawn copper wire that won’t stretch. Old timers will know that trick!!!
Open wire feeders???? They don’t have to be expensive 450 ohm ladder line!!!!! Learn how to cut a bit of plastic to make insulators about 2 inches across. A small hole or slot in each end will allow you to thread the insulators onto the wires. Any wire will do. A local mate of mine uses #18 galvanized garden wire. A roll at Mitre 10 for 6 bux!!!!! You only need a 34 foot length of feedline.
Insulators??? One side of a plastic clothespeg. 16 clothepegs at the supermarket will set you back about 3 bucks. Any plastic will work. Currently, for all my insulators and antenna materials I go into the supermarket and buy a nylon chopping board. I then use a small jigsaw with a coarse blade and can cut out anything I need in a few minutes. I would strongly suggest that you don’t purloin your XYLs kitchen board in the heat of the moment or you will experience severe RF sparking and possibly meltdown.
“But it might not work” I hear you say. Get over it. Learn how to solder. Get hold of a mate in the your club to help. Build the bloody thing and get a mate with an antenna analyzer to put it on resonance and it will work just the same as a $195 one and you will learn a helluva lot about antenna and how to put them up. There are tons of books and lots of antenna information on the net. I just Googled G5RV antenna construction and I got 41,000 hits. The first ten gave me endless possibilities for construction.
Building an antenna is not rocket science guys. There is nothing magical about a store bought antenna.
Sorry … there are magical. They make your money disappear in a flash!!
73, Lee ZL2AL