Topband: one- way propagation

[Tom W8JI]

> Here some interesting paper about LF MF polarization
>
> http://www.ann-geophys.net/22/1705/2004/angeo-22-1705-2004.pdf
>
> This paper, High-latitude propagation studies using a meridional chain of
> LF/MF/HF receivers

I stop reading when I get to this point:

"The receivers used in this study involve one of two antenna
types: electric or magnetic dipoles. In both cases, the antenna
is nonresonant at all frequencies detected. The electric
dipole consists of a 3m vertical rod elevated approximately
3m above the ground. The magnetic dipole consists of a
10-m2 magnetic loop antenna oriented vertically at an angle
which nulls out the strongest local interference signal."

When the methodology is questionable or wrong, why should we trust the 
results?

1.) To receive horizontally polarized waves at a reasonable wave angle 
(compared to a vertical) requires either  a substantial antenna design to 
suppress vertical component and high angle components, or it requires the 
horizontally polarized antenna be exactly broadside to the arriving signal 
and at least 1/2 wave above earth.

2.) Response levels to be equal, or compensated.

A "magnetic loop" is radially polarized. At various angles and directions 
polarization changes. It is entirely vertical in some directions, and 
horizontal in others, and tilted polarization at most angles and directions.

Even a dipole has that problem. A dipole is only perfectly horizontally 
polarized directly broadside to the dipole. Off the ends, it is vertically 
polarized.

QST ran some articles about X-O stuff that was equally flawed in concept and 
methodology.

Measuring polarization is easy on upper HF or higher where wavelength is 
short and a horizontal antenna can be rotated broadside and placed at 
reasonable heights. It is nearly impossible for most people below 40 meters.

When the basic sensors used for measurements are seriously flawed, there 
isn't much reason to read the results.

73 Tom