View Single Post
  #2   Report Post  
Old May 18th 05, 04:40 AM
Frank
 
Posts: n/a
Default

"Henry Kolesnik" wrote in message
...
As I understand it a shielded loop (non-magnetic shield) favors the
magnetic field.

Correct.

If I wanted to measure the difference between the 2 fields how would I
measure the electric field?

Any antennna can measure the electric field, you simply have to know the
antenna factor.
Antenna factors can be calculated for various structures; for example the
aperture of a half wave dipole is given by: 0.13*lambda^2. Simple
calculations can then provide the antenna factor, and relate the E field (in
V/m) to the received signal. The electric and magnetic fields are related
by a constant -- the impedance of free space, 377 ohms. i.e. E/H = 377.
In the vicinty of an antenna (the near field) the impedance of free space
becomes a complex number.

A loop shielded with magnetic material would probably reject both fields.

Probably true, but have never experimented with such antennas.

The 3.5 foot loop for my old HP comparator for WWVB is totally
non-magnetic.


Can I generate and transmit each field separately? If so how would I do
it?

No. The E field cannot exist without the H field. See the relationship
above. Some people claim to have invented antennas that seperately generate
E and H fields. Such antennas are known as "EH" and "Crossed-field", and
have largely been rejected by the engineering comunity as bogus. The
designers claim that they do not conform to Maxwell's Equations, but some
other indefinable mathematics.

Regards,

Frank

tnx

--

73
Hank WD5JFR