[TowerTalk] K7C - One-Way Propagation?

Bill Jackson k9rz at radiks.net
Mon Oct 3 08:09:22 EDT 2005


Towertalk Gang,

Here is an excerpt from one of the recent K7C dx'pedition bulletins, regarding poor signal quality they appear to be experiencing on their end:

"Let's start with a technical consideration of which you should be aware.  As you already know, we are using vertically-polarized antennas very, very close to salt water and with large radial fields. This makes our signal launch angle very, very low - quite a bit lower than most horizontally-polarized antennas on dry land.  As a result, the K7C signal has been reported to be very loud on the receiving end. This doesn't mean, however, that you are just as loud here.  All it takes is a couple of extra "hops" from a higher launch angle and your signal will change from an easy-to-work S5 to being undetectable.  The K7C team has observed a number of occasions when it is obvious that you can hear K7C easily, but on our end the pileup is only an unworkable S-1 grumble.  This is most pronounced at the beginning and end of an opening so you may be hearing us long before or after we can hear you.  Marginal openings on the paths to Europe, the Middle East and Northern Africa may be entirely "one-way" - incredibly frustrating for you to have K7C be as clear as bell, but not hearing the most important DXer of all - you."

Does this explanation make sense?  I would think that an antenna with a high angle of radiation on transmit would also favor signals with high arriving angles on receive.  The amount of signal attenuation on a signal arriving at a low angle at the station with the antenna transmitting with a high angle of radiation should be equally diminished.  Therefore the station with the horizontal antenna over dry land should have trouble hearing hearing K7C as well.

What am I missing here?  

Even though I have managed to work them on both 80 and 40m, they have never had what I would call a LOUD signal, compared to what I often hear from KH6 land.

73 de Bill



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