Banana Plugs are more used in the sound industry, but it has a variant, which is useful for Hams. The BNC variant which is available in both Male and Female types can be used to quickly make a dipole antenna ranging from 14 MHz Ham band to 2.4 GHz (Wi-Fi Antenna).
Upon discussion, with a couple of Hams about this Banana Plugs, I got mixed reviews. One of them told me it’s useless; the other told me it’s the best QRP (Low Power) field antenna one can have, easy to assemble and disassemble. You also get the flexibility to make an antenna of whichever frequency you wish to. Like 2 Mtrs, 70 Mtrs ham bands.
To try and experiment with it, I ordered it from Aliexpress, which arrived at my place in 35 days. I ordered not just one but 2. Because I wanted to break open one of the plugs to find out what’s inside. I mean the material used and the thickness of it. As you can see in the image below, I have broken the banana plug and placed a magnet in between the jacks, but no attraction.
It means it is made up of either steel, brass or copper. I then used a file on it and found the light golden colour, which means it is made up of brass. The wires connecting to the BNC is quite thin (24 Gauge) see the green marking on the image below. That means you should not transmit more than 25 watts, or else you’ll end up blowing your radio.
So I decided to test this Banana Plugs. I made an HF Dipole antenna, using two wires (1 Sq. mm) 16 Ft and 3 inches at each end. The formula for making a dipole antenna is 468/Frequency in MHz, the result you get is in Ft. Therefore 468/14.2 MHz is 32 Ft and 6 Inches.
This is the amount of wire that you need for this antenna. Now you cut that wire into two equal parts and attach at two different jacks of the Banana plugs. Here is a step by step process for making the dipole antenna to be used with banana plugs.
1) Remove 5 to 6 cms of the shield from the copper wire.
2) Tie the copper wire with one round to find out the size of the Jack, before you tin the wire.
3) Insert shrink sleeves in the Copper wire from the other end.
4) Tin the copper wire so that it holds all the strands and make it strong.
5) Copper wires are now tinned in round shapes.
6) Apply heat on the shrink sleeves with the lighter. I know that’s wrong, but it’s an improvised method, I learnt from a Parsi Ham friend.
7) Wire for the HF Dipole antenna is ready for using with Banana Plugs.
8) The tinned holes of copper wires are inserted in the jacks, for dipole antenna.
9) QRP (Low Power) Antenna for 20 Mtrs band (14.074 MHz) with banana plugs is ready to use.
I then tested this antenna with my antenna analyser (MR100), in one shot I got the SWR of 1.4 (For 14.074) which is used for FT8 (Digital Mode Communication). See the screenshot below taken from the PC software used for tuning the HF Dipole.
I used it on FT8 and was able to have a successful QSO till Europe on just 10 watts with confirmed QSL.
I then made dipoles for other Ham Bands also 144 MHz (VHF), 434 MHz (UHF) and even made a Wi-Fi Antenna for using with my wireless card. I tested this antenna with my Home Wi-Fi network, and it worked perfectly. This way you can extend your antenna with the help of a cable-like RG-316 Coax Cable and connect to your wireless card, mainly if your router is located at a longer distance.
At the cost of just Rs. 100 this is worth having in your shack. The other thing that you may want to buy is BNC to UHF adapters to use with standard 50ohm coax cables. If you wish to buy a heavy-duty Banana plug for transmitting 1 Kilowatt then you will have to spend Rs. 5,100 (USD 70) + Shipping charges extra. One of my ham friends has bought it and tested it with 1 Kilowatt (Not in India).