The only way to determine the characteristics of an antenna is to measure its performance, since theory alone cannot predict the actual results. The fields generated by antennas are extremely complex because they interact with everything in the environment. Given this complexity, antenna measurement and analysis will be more successful if you use an experienced and accredited antenna laboratory equipped to handle the tests, standards, and their nuances.

This article is the second of a two-part analysis of antenna theory and design for a remote-keyless-entry (RKE) application. The first part of this article, Small Loop Antennas: Part 1—Simulations and Applied Theory, explains the complexity of antenna analysis, presents several simulation tests, discusses test results, and compares the benefits and limitations of short-loop or open-loop antenna designs. This article, Part II of our discussion, focuses on the actual antenna field tests that incorporated some of the techniques and test parameters required by the FCC for certification of a device. Using the Maxim antenna board presented in Part I, an outdoor ‘real-world’ field test was performed. The theoretical results presented in Part 1 are compared with actual field-test data.

The article does not describe how to perform actual FCC testing; that is far beyond the scope of the discussion. Our goal, rather, is to help the reader understand what design and environmental issues to expect when a device is tested.