Thursday, December 17, 2009

KAAY's Ground & Antenna System

The Wonderful, The Marvelous (wait, that was reserved for "Marvelous Mark"), The Man Lee Roy, checks in with more interesting information about the KAAY antenna and ground system in the heyday:

"Bud, from my fuzzified memory, KAAY used a hybrid ground system that was not completely unusual. Beginning at the base of the tower and radiating outward for about 25-30 feet, the ground system was above ground. The center tower sat on a concrete pylon, about 6-8 ft tall, and you could safely walk right up to the base of the tower, (your entire body was below the ground halo). At the end of the halo, the ground system went underground and continued for another approximately 500 ft, with one radial every 3 degrees (**).

When we rebuilt the ground system in the 70’s, we added a complete new set of radials for each tower in-between the original radials (**). This made the ground system look like a radial every 1.5 degrees, alternating between an “old” one and a “new” one. I don’t know if the ground system has been reworked since then but maybe someone else may know (??).

All the power divider network and phasing networks were in the center doghouse. The transmitter RF output came into the center doghouse via a rigid coax. Depending upon daytime or nighttime operation, would depend upon how the phasor and ATU were coupled into the towers.

In daytime, the entire transmitter RF went into the ATU for the center tower, and the two outside towers were “detuned”. In nighttime operation, the RF came first into the center doghouse power divider, then the phasor, and then into a rigid coax running to each end tower’s own doghouse. Each tower had its own ATU, and base currents were read remotely. But the power divider and phasor for each of the end towers was located in the center doghouse. All the switching between the daytime and nighttime phasor / power divider / and three ATU’s was done using several inter-coupled high power RF relays, and everything had to work “just right” when changing from day to night and vice-versa.

/D/ "

For those who may not understand the reasoning behind ground radials, an "earth ground", many times, is not sufficient for proper matching and power transfer...basically, the ground radials act as the "other half" of the antenna in a much more efficiant manner than dirt can.  If a broadcaster can place the transmitter in a marshy area, then, so much better the signal, even with ground radials.  A good ground radial system will act as a mirror or reflector, if you will, helping to launch the signal to you, the listener!  This is VERY important with vertical antennas, especially the lower in frequency the transmitter operates.

If there is no (or little) radial system, the transmitter, no matter how big, will not transfer the power efficiently, causing all kinds of problems...especially from the Federal Communications Commission!

Again, thanks to Dave M., The Man with the fantastic brain for engineering!  (Boy, he'd make an excellent Ham radio operator!)

Bud S. (

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