Saturday, February 11, 2012

160 metre "L" Antenna

160 metre "L" Antenna

 One of the problems with short, low antenna's on 160 metres is that their input impedance is very low, usually on the order of a few ohms.
 A clever trick to overcome this is to intentionally make the antenna to long. This will make the resistance increase, but also add inductive impedance.
 Simply add a series variable capacitor to tune it out.

 I use an "L" shaped antenna on 160 and have had very good results. It is a total of 165 feet long and shows an impedance of 50 ohms+j88. It is not necessary to know any maths or have an expensive impedance bridge to use this antenna. Just make the capacitance variable and you'll be in the ballpark.
 Adjust with a SWR meter, cut and try adding or subtracting the length. Its not critical at all. The horizontal part can be routed just about anywhere. Try to make the vertical part as high as possible.
 For the ground Iv'e tied everthing together, furnace ducts, ground rods, house ground, dogs chain (just kidding !), and radial system, with braid from RG8/U.
Does it work?, You bet!!
49 States on CW including Hawaii, and just about that many on ssb with only 100w output.

ALSO..... I feed it with a tuner as a long wire and with QRP I've worked both coasts. On the higher bands the capacitor's impedance is so low it makes practically no difference if you leave in or take it out.

Gud Luck and CU on 160

1 comment:

M.T. Jones said...

This interest me. Have you had any other reports on its use?