The Predicted Coverage of the
NLARC 146.07/67 FM Repeater

The propagation prediction plot above was generated using the excellent Radio Mobile Freeware V 3.7.8 application by VE2DBE for radio propagation and virtual mapping. Additionally, you may visit the Virginia Digitial Emergency Network (VDEN) site to obtain various maps.

The plot above was generated using the following parameters:

• Antenna height above ground level (240 feet/73 meters).
• Transmitter Power (85 Watts at the output).
• 52 Ohm coaxial feeder (RG-213, 2.8dB/100 ft., a 3 foot run is used), (-0.09 dB).
• Circulator insertion loss (-1.0 dB).
• 52 Ohm coaxial feeder (RG-213, 2.8dB/100 ft., a 3 foot run is used), (-0.09 dB).
• Duplexer insertion loss (-1.25 dB measured).
• 52 Ohm coaxial feeder (RG-213, 2.8dB/100 ft., a 15 foot run is used), (-0.42 dB).
• Q-Section (50 to 75 Ohms Z) insertion loss (-0.1 dB).
• 75 Ohm Air Dilectric Coaxial cable loss (0.4 dB/100 ft., a 270 foot run is used), (-1.1 dB).
• Q-Section (75 to 50 Ohms Z) insertion loss (-0.1 dB).
• 52 Ohm Coaxial Feeder (RG-213, 2.8dB/100 ft., a 25 foot run is used), (-0.7 dB).
• 4 gamma matched dipoles in a phased array, arranged in an "H" pattern (+6 dB broadside, +4 dB inline).

The resulting loss of the transmission line and components + the gain of the antenna: [(-0.09) + (-1.0) + (-0.09) + (-1.25) + (-0.42) + (-0.1) + (-1.1) + (-0.1) + (-0.7) + (+6.0)] equals about +1.15 dB. Factored into the 85 Watt output directly from the transmitter, this results in a 110 Watt ERP (effective rated power) rating. These calculations are estimated to be accurate to plus or minus 10%.

Web page operations: James E. Byrd
Responsible NASA Official: Richard S. Eckman