RF test antennas and selective filters for the broadcast engineer

Chris Scott & Associates - www.scott-inc.com

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RF test antennas and selective filters for the broadcast engineer

AM and fm broadcast stations are required by the FCC to make periodic signal integrity measurements, some of which are designed by the National Radio Systems Committee. The instrument of choice is the spectrum analyzer coupled to a suitable antenna. While approximate AM readings are sometimes obtained with "whip" antennas, the severe impedance mismatch and lack of calibration yield imprecise results. Harmonic measurements require that a known antenna factor be employed to convert spectrum analyzer input voltage to field intensity units. The industry standard LP-3 provides this calibration.

Another key tool is the AM notch filter, which is often necessary to eliminate errors when measuring harmonics with a spectrum analyzer. Frequently, internal non-linearities create artificially high harmonic or spurious indications when the fundamental carrier is unsuppressed.

By "notching" the primary frequency, reliable accuracy is ensured. Our low-loss port on the am notch filter allows measurement forays well below -80 dBc at +- 75 kHz, which are required when conducting NRSC tests on stations with power levels of 5 kw and above. See Breaking the 80 dB barrier.

For FM harmonic measurements, we offer a 175 MHz hi-pass filter to attenuate the FM band while passing harmonics. The completely shielded designs provide ultimate stop-band attenuation.

Chris Scott & Associates is a small design and consulting firm specializing in radio broadcast. A partial listing of clients and customers is available.

Whether your visit to our website is professional, or is simply curious browsing, don't miss the "white" papers presented, covering related topics.

Tunable AM notch filter. (out of production)
LP-3 Standard H-field loop antenna... for AM NRSC and harmonic testing with a spectrum analyzer. (out of production)
175 MHz High-Pass filter for FM harmonic measurements.
Ten MHz Low-Pass filter for AM measurements.
FM Bandpass filter for out-of-band rejection.

Will a new FM antenna help my coverage?
NRSC Measurements: Breaking the 80 dB barrier
AM NRSC bandwidth measurements with the LOOP antenna.
Field tuning ERI fm antennas. How to do it yourself.
A new look at the Ufer ground. 1989 RW article.

Pricing & ordering

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Chris Scott & Associates
P.O. Box 52
Bowling Green, KY 42102

Phone: (270) 781-5301

Pricing & ordering

Partial listing of clients and customers