H FIELD ANTENNAS?
"Roy Lewallen" wrote
Very close to a small loop antenna, response is greater to an H field than
E field. It does respond to both, however, as all antennas must. As you
get farther away from the antenna, the response to the H field decreases
in relation to the E field response. At around an eighth wavelength
distance from the antenna, the response to E and H fields are about the
same as for a distant source. Beyond about an eighth wavelength, the
response to the H field is actually *less* than the response to an E field
compared to a source at a great distance. The ratio of E to H field
responses then decreases to the distant value as you get farther from the
antenna.
In summary, the antenna responds more strongly to the H field if the
source is within about an eighth of a wavelength from the antenna. Beyond
that, it actually responds more strongly to the E field relative to the H
field than a short dipole or many other antennas -- you could more
properly call it an "E-field antenna" in its response to signals beyond
about an eighth wavelength. The difference in relative E and H field
response among all antennas becomes negligible at great distances; for
antennas which are small in terms of wavelength, the difference becomes
negligible beyond about a wavelength.
But according to W8JI "teachings" there is no way that electrostatic shield
on a small loop antenna would work as a shield, attenuating E field dominant
signals or noise generated within that 1/8 or about wavelength.
According to him, it works as an antenna. Some scientwists can not
comprehend that electrostatic shield shunts the predominantly E field
generated in the vicinity. It is the FACT, easily observable by anyone
building shielded small loop and having TV birdies, PS bricks or arcing
noise source within about 1/8 of a wavelength.
W8JI wrote:
Seriously, precipitation static is caused by corna discharge from an
antenna or object someplace near the antenna. The radiated field from
that leakage current can be almost any field impedance and will always
be a mixture of time-varying electric and magnetic fields.
Roy, 'splain to him about this 1/8 or so thing. He still dungetit.
73 Yuri, K3BU
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