Washington Laboratories (301) web: Lindbergh Dr. Gaithersburg, MD How to List a Test Site

Listing an Open Field Site William H. Graff oPresident and Director of Engineering o Major Chen oManager East Asia Branch Office o

What is an OATS? An Open Area Test Site is the minimum requirement, other than measurement instrumentation, for making radiated emissions measurements

Reference standard The FCC uses ANSI C for determining the suitability of an OATS. Standard open air test sites are considered in section of this document Semi-anechoic chambers are considered “alternative test sites” and are seen in 5.4.2

Basic description Open, flat and level Clear of overhead power lines Clear of RF reflecting structures Covered with hardware cloth or other conductive material Minimum dimensions for common 3M OATS is 6M x 5.2M

Basic Facility Must have a remotely controlled antenna positioner and mast capable of being raised to 4M ad lowered to 1M Must have a continuously rotateable remotely controlled turntable metal covered and flush with the groundplane.

Antennas Must have antennas capable of measurements over at a minimum 30MHz to 1GHz. If transmitters are to be tested, then the laboratory must be mindful that a frequency range typically to the 10 th harmonic of the fundamental measured is required. o433MHz key fob needs measurements to 4.3GHz

Site Attenuation Measurements Basic procedures given in and of ANSI C63.4 Measurements must be done on both horizontal and vertical planes Complex procedures for “alternative sites” include “test volume” measurements. Data must match the theoretical “site attenuation” curve to +/- 4dB

Powerline Conducted Measurements Use of a Line Impedance Stabilization Network (LISN) is required. If used with an OATS, the LISN must be under the groundplane.

Listed Site Test Report Considerations All test equipment and antennas must be calibrated. All antenna factor tables and LISN loss factors must be presented. All cables used in tests must be calibrated. All photographs shall be clear, in large format, and only one to a page

Submission to FCC The site attenuation data along site photographs must be submitted electronically to the FCC

Patience It is not unusual for the FCC to take a month or more to finish analyzing the Test Site data. Expect questions on a new facility when information appears unclear to the examiner. Be sure to respond quickly to the examiner’s questions. Do not test anything until approval is received.

Questions?