Topband: Power Coupling for K1B

[Robert Brown]

Friends in Radio Land -
 
     With the recent discussion about magneto-ionic power coupling
and the present interest in the K1B DXpedition, I have calculated
the insertion loss to and from the lower ionosphere at K1B using
data obtained from the International Geomagnetic Reference Field
(1990).
 
     K1B is at a low latitude where the field is within 2 degrees
of being horizontal, much like the situation at Togo during the
5V7A DXpdedition that I mentioned in a recent posting.  The data
given below shows the large (>10 dB) insertion loss for E-W
propagation with a vertical antenna.  In that regard, it would be
of interest to examine the K1B 160 meter logs to see the extent
to which E-W propagation was affected.
 
     With a high dipole oriented in the N-S direction, the loss
would only be about 0.2 dB in the E-W direction.  But a high
dipole oriented E-W would be as effective in the N-S direction
(about 3 dB loss) as a vertical antenna as the horizontal
geomagnetic field presents the same aspect to both horizontally
and vertically polarized waves from the antennas.
 
     Again, a detailed discussion of power coupling is to be found
in the Spring 1999 issue of the Communications Quarterly.
 
                   Power Coupling Loss for K1B
            O-Wave, 20 deg rad angle, vertical antenna
 
         Heading       Loss            Heading       Loss
       degs E of N     (dB)          degs E of N     (dB)
 
        000 - 015      -2.8           180 - 195      -2.8
        015 - 030      -2.9           195 - 210      -2.9
        030 - 045      -3.1           210 - 225      -3.1
        045 - 060      -3.5           225 - 240      -3.5
        060 - 075      -4.3           240 - 255      -4.3
        075 - 090      -5.9           255 - 270      -6.1
        090 - 105     -10.7           270 - 285     -12.0
        105 - 120     -14.6           285 - 300     -14.3
        120 - 135      -6.3           300 - 315      -6.3
        135 - 150      -4.1           315 - 330      -4.2
        150 - 165      -3.2           330 - 345      -3.3
        165 - 180      -2.8           345 - 360      -2.8
 
73,
 
Bob, NM7M