I have seen many reasons for using 1/8, 1/4 wave radials, etc.. However,
RF is very empirical. The results often differ slightly than the theory.
I am an experienced design engineer with 30 years experience, I cut my
teeth in AM and UHF TV broadcasting before obtaining my BSEE. I have 40
years plus amateur radio building and operating experience. The
following is what I have found WORKS.
First as many radials as possible of any length if the antenna is ground
mounted. Ground rods as long as possible at the base of the antenna. I
use at least three 8 foot ones. I also use short 3 to 6 ft ground rods
at the end of each radial.
Results, I have worked other stations all over the world on SSB and CW.
Last year I ran several beacon tests. Result: The best signal reports
in both quantity and signal level came from the direction of the longest
radials. No reports came from a couple of areas without radials in that
direction. My power level was 250 milliwatts. Many signal reports were
579 to 599. Average 459 to 579.
SO put down as many as possible of all lengths. What ever your property
provides room to do. Use all the copper you got. Covered, uncovered,
etc. I like to have it about 6" below the surface. Tune the antenna
after the radials are all down. I tune by varing the vertical length
until I obtain a 1:1 VSWR at the base of the antenna. I then feed the
antenna with 1/2 wave of coax (electrical length). I use a grid dip
meter to tune the coax length (see how to do this in some of the old arrl
handbooks).
Then call CQ and have Fun.
73 de stan AK0B
[
QRP-L Archive |
]
[
1993 |
1994 |
1995 |
1996 |
1997 |
1998 |
1999 |
2000
]