Re: [IRCA] SAN FRANCISCO 49ERS RADIO NETWORK
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Re: [IRCA] SAN FRANCISCO 49ERS RADIO NETWORK



Title: SAN FRANCISCO 49ERS RADIO NETWORK
I tend to not think of KNBR as having a big signal. Both KCBS (DA-2) and KGO (DA-1) are extremely strong down here with little fading; KNBR sometimes gets as strong but fades more often. 
 
They are using a so called Franklin antenna which is somewhat unusual. It is used as a means to lower the radiation angle of the signal. This increases the ground wave coverage of the station, and reduces the night time interference at the fringes of the ground wave signal, caused by sky wave signals originating from the same tower. A traditional Franklin antenna consists of two half wave antennas stacked end-to-end and fed in phase. At 680 khz. this would be a 1,500 feet!! The KNBR tower measures 400 ft. to the midpoint insulator. The upper portion of the tower is shortened to only 150 ft., and this is compensated for by a 50 ft. diameter capacitive top loading "hat" at the top of the structure. The top section is fed from a shunt tap on the lower section. There is a copper tube that runs up from the tap on insulated stand-offs, where it connects to the upper section just above the insulator. 
 
All three have excellent ground systems.
----- Original Message -----
From: Art Blair
Sent: Monday, July 25, 2005 8:46 PM
Subject: Re: [IRCA] SAN FRANCISCO 49ERS RADIO NETWORK

Yeah, looks skimpy, but that is the info on the Niners website. First year for KNBR. We shall see if they add more stations.
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