J-Pole antenna is an end-fed omnidirectional antenna that should be fed with 50-ohm impedance balanced line. When fed with coax (whether it is an RG-58 or RG-8) cable, it should be connected with air-choked balun.
There are several variation of J-Pole antenna, including the Slim Jim and also the ladder-line J-pole suitable to be used with hand held transceiver.
Here is the plan for a typical J-Pole antenna (measuremant in inches):
Copper tubing is usually used as the construction material for J-Pole antenna.
A mounted J-Pole antenna:
Alternatively, you can buy ready-made J-Pole antenna for hamradio transmission from KB9VBR J-Pole Antennas.
Foxhole radio receiver or Crystal receiver is a form of radio that does not operate on local oscillator, which makes it hard to be detected by other electronic device. One of the most interesting thing of Foxhole radio is that it could be operated without the use of batteries, as it is powered solely by the radio waves through its long wire antenna.
Foxhole radio was (supposedly) popular during World War II because it enabled the GI to receive radio broadcast in the middle of the war, particularly in France as the Germans has outlawed the use of radio by civilians, thus the American GI need to build their own receiver to receive broadcasts. Typical component of foxhole radio during those days are : a period razor blade (not the newer galvanized one), carbon (obtained from pencil) and some copper wire with woodblock or cardboard as its base.
I’ve found a video on Youtube on how to build a Foxhole receiver, it still requires considerable skills and experience to build a working version of the receiver though.
Late this few weeks I’ve been hunting and finding Solar Panels which can be use to power up various items. Among the Solar Panel that I’ve found is listed below.
1. 14 volt panel – obtained from a hobby shop
2. 4.5 volt panel – scrapped from a damaged garden light
3. 2 volt panel – scrapped from some car accessories
Why would I need solar panel for?
Just to satisfy my hobby in electronics. The place where i’m staying (Alor Setar, Malaysia) always receives equal amount of sunshine, (near the equator), except for monsoon season of course. So I’m thinking that, it’s kinda shame if I let it waste.
Among of my plans would involve of hooking up one of these panels with a regular car battery and inverter to power up my backyard lamp and various electronic projects that depends on solar power. I’m looking for any good schematic to aiding me, not too complex, but good enough for a beginner.
I would appreciate any of your suggestions, btw.