Some New Antenna Systems can dump 200 milliwatts of RF into your ENG Receiver!
If a PCS, MDS, Wireless Cable, New 3G/4G (2110-2150 Mhz), or other High Power Site moves in near you, it could fry your receiver!
This is the ANRITSU 37247B Network Analyzer with the latest (1/14/'98)
Microwave Radio Filter sitting on top. After a full 12-Term Calibration was performed
(precision references were used), the Marker Readout (attenuation) is shown below.
MARKER 1) Center of 2 Ghz ENG Band
MARKER 2) Upper part of Block C PCS Band
MARKER 3) Middle of Block C PCS Band
MARKER 4) Low end of Block C PCS Band
MARKER 5) Upper edge of Block B PCS Band
This filter comes after the antenna, and is followed by an LNA that is capable of delivering a sustained power of around 200 milliwatts. This antenna system was to be connected to a tower-mounted receiver only a few feet away! High RF, or even a pulse from a lightning strike, could fry the receiver's front end
If a -20 dbm signal in the middle of Block C PCS hits this Microwave Radio antenna system, the gain of the antenna brings the signal up to about -1 dbm. The filter attenuates the signal about 9.6 db, and then it is amplified 25 db by the high power LNA. This brings the output power up to about +15 dbm. This unit was scheduled to be placed into service, connected to a receiver a few feet away. The receiver could have died a quick death!
Even worse, if a -20 dbm signal at the upper part of Block C PCS hits this Microwave Radio antenna, the gain of the antenna brings the signal up to about -1 dbm, but the filter would only attenuate the signal less than 2 db. The signal would then be amplified 25 db by the high power LNA. This would bring the output power into saturation at around +23 dbm, or 200 milliwatts! This is enough power to permanently damage virtually any ENG receiver.
Receivers like to see microvolts, not milliwatts.
In all fairness, the design of the filter, it's group delay, and the linearity of the amplifier, all look good on paper, but may not be acceptable under real world conditions. A 25 db, high power amplifier should never be connected directly to a receiver, and a filter that passes PCS is not practical for today's high power, out of band signals.