Hittade mer om de här typen av antenn. Kallas tydligen T2LT (Tuned Transmission Line Antenna) Finns mängder av info och utubes om att tillverka den.
Googla "t2lt cb antenna"
T.ex.
http://www.transmission1.net/viewtopic.php?t=33559"Blue Runner wrote:
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Make the simplest, cheapest, easiest NO GROUND PLANE CB base antenna in the world!
Make a rope eye on one end with about 6" of extra length twisted around the long part of the wire. Measure 103" from the outer tip of the rope eye and cut it.
Solder, butt splice or wire nut the cut end to the center conductor of the coax to the end of the wire. Read my notes below - Homer
http://i1205.photobucket.com/albums/bb4 ... 7684b6.jpgDO NOT CONNECT THE SHIELD TO ANYTHING; make sure none of the hairs are touching the center conductor. Waterproof the connection (stretch tape, silicone etc).
Mark the coax at 9' from the splice. Wrap 6 turns of the excess coax around a 4" PVC piece of pipe. Tape or tie wrap the coax down securely to the 4" form.
Hoist the antenna up on a piece of rope into a tree OR attach it to PVC or wooden mast. Metal pipe can be used about 2' below the choke.
Connect the end of the coax to your SWR meter and tune the SWR by making the wire longer or shorter by just pulling some wire out of the twisted end or pulling more onto the twist. Very easy no cutting or insulation stripping.
How it works?
Current flows to the antenna on the surface of the center coax conductor and the surface of the inside of the shield. Currents also flow "from the antenna" on the outer surface of the coax shield at the same time. This is called common mode currents and we usually try to get rid of them because they skew our SWR & power meters, cause harmonic off band radiation, pick up interfering noise and can also shock the radio operator if he is using high power.
Several methods are used to stop common mode currents that include putting a string of ferrite beads on the coax or a simple air choke made of coils of the coax transmission line. We usually put them right at the base of the antenna for max efficiency.
On this "Worlds Cheapest antennas" we put the choke 1/4 wave length from the base of the antenna (9') and use those common mode currents for the other half / "ground plane" counterpoise of the antenna.
The choke should also pinch off any common mode currents below it, making the antenna work and eliminating the common mode problem all the way back to the radio.
NOTE:
This is the reason why a choke should only be placed at 9' below them super, no ground plane antennas. They are using the coax for a ground plane / counterpoise too, but not making any attempt to get rid of the "excess" common mode currents further down the coax.
This looks like the ultimate emergency antenna. Don't need nut'n but the coax transmission line. If you are patent enough to strip off the shield for the first 103" you don't even need any extra wire.
I have no idea what the radiation pattern might be. It looks to me that it should be the same as a center fed verticle dipole.
I have it pulled up to 60' high, the same height as my Star Duster and about 30' away from it. I compared listening & transmitting to Skip & locals on it and my Star Duster and neither I or they could tell any difference.
I have been . . . trying to make an emergency antenna that can be easily rolled up compactly and easily hung from a tree or building I made a buncha different ones, and this one has ‘em all (other antennas he tried) beat for performance, simplicity and compactness and took less than an hour to build, tune and get radio checks from."
//reboot