Re: NEC-LIST: Horizontally polarised MF antennas

Hi

Thanks for the response so far.

John Wood asks

"The "magnetic dip equator?" Is this a troll? If not, could you
please put this jargon in plain English? "

As I understand it:

At all points on the dip equator the earths magnetic field is
horizontal. The dip equator passes through Brazil, across W Africa,
Sri Lanks, Thailand, through the Phillipines, and on to Bolivia. ITU
Recommendation P1147, which supercedes REC435, indicates that signals
transmitted from conventional vertical radiators along the dip equator
would suffer over 25 dB absorption. This is because the gyromagnetic
resonant frequency for the free electrons in the ionosphere falls in
the MF band. If the E field is normal to the magnetic field the
incident ray will trigger gyromagnetic resonance, the elctrons collide
and the ray energy absorbed. The trick is to turn the ray round 90
degress in the E-W direction, but how ?

George Hagn asks:

You didn't define long range, ......

The range would be 500km N and S, and as much as 1500km E and W. Is
this feasible? The trade off seems to be about 25 dB using a vertical
antenna against the maximum power possible into a horizontal one (at
least in the E-W direction).

Thanks

Phil
Received on Mon May 15 2000 - 04:05:20 EDT