[Antennas] How low can you go?
Robert I. Block W2SR
[email protected]
2002年5月24日 13:40:01 -0400
What is the lowest practical height for a) doublet antennas for 3 -30 MHz and b)
for tuned radials?
I seem to recall that antennas will operate even underground, and that one
design for a stealth antenna is a doublet very near the surface. One of the
Antenna Compendiums contains an article documenting results of a tuned
counterpoise 8 inches (about 200 mm) off the ground. At some point, I expect
that elements are detuned to the extent that no resonance is observed, this is
not a problem for the antenna, but at that point the radials are simply a skimpy
ground system. What happens if tuned radials (whether tuned by length as in the
conventional conception of a ground plane, or collectively as described by Les
Moxon) are connected in parallel with ground radials at the ground side of a
vertical antenna?
Oh yes, I'm quite aware that a doublet at low height results in high-angle
radiation and that high RF voltages are present at the open end of tuned
radials.
73,
W2SR