FCC Test Equipment & Facilities Requirements 2

Question 1

What is a 'log-periodic dipole array' (LPDA) antenna and what frequency range does it cover in FCC testing?

Accepted Answer

A wideband antenna used for radiated emissions measurements typically from 200 MHz to 1 GHz

Answer

An LPDA is a broadband directional antenna whose element lengths and spacings are scaled logarithmically, providing relatively flat gain and impedance characteristics across a wide frequency range, typically used from 200 MHz to 1 GHz in FCC emissions testing.

Question 2

What is the function of a preamplifier in an FCC radiated emissions test setup?

Accepted Answer

To boost weak signals from the receive antenna above the noise floor of the spectrum analyzer/EMI receiver

Answer

A preamplifier placed close to the receive antenna amplifies the incoming signal before it travels through the coaxial cable to the receiver, improving the overall system sensitivity and ensuring that weak emissions above the noise floor can be measured accurately.

Question 3

What safety consideration must be addressed before placing personnel inside a shielded chamber during active RF testing?

Accepted Answer

RF exposure must be evaluated and personnel must not be present when transmit power levels exceed safe exposure limits

Answer

RF energy levels inside a shielded chamber can exceed FCC maximum permissible exposure (MPE) limits when transmit antennas are in use, so personnel must not enter the chamber or must be protected when RF fields above safe levels are present.

Question 4

What is the required height range for a receive antenna during FCC semi-anechoic chamber radiated emissions testing at 3 meters?

Accepted Answer

1 to 4 meters above the ground plane

Answer

ANSI C63.4 requires the receive antenna to be scanned in height from 1 to 4 meters above the ground plane (in a semi-anechoic chamber at 3-meter separation) to find the height that maximizes the received signal level.

Question 5

What is a 'hybrid chamber' or 'giga-cell' in the context of FCC testing above 1 GHz?

Accepted Answer

A test facility that combines shielded room construction with partial absorber lining to perform measurements above 1 GHz according to ANSI C63.4-2014 or similar standards

Answer

A hybrid or giga-cell chamber uses absorber on portions of the chamber walls to reduce unwanted reflections for measurements above 1 GHz where a fully anechoic environment is required, allowing testing per ANSI C63.4-2014 above 1 GHz in an indoor facility.

FCC - Federal Communications Commission Certified Laboratory Practice Test

FCC - Federal Communications Commission Certified Laboratory Practice Test

FCC Test Equipment & Facilities Requirements 2