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transmitter harmonics, TIS failures due to self-interference, and TRP failures due to compromised antenna efficiency.”

Failure to meet FCC regulations is rarely an antenna-only issue. The antenna cannot produce emissions on its own, although the antenna can influence transmitter harmonic generation that can lead to FCC test failures. Generally, FCC failures are system related issues which may involve the antenna.

Devices intended for operation on the AT&T network must display high antenna efficiency and a low level of self-interference in order to meet AT&T's acceptance criteria. Devices with antennas which fail to meet AT&T's TRP requirements may not only be inefficient, they may create other problems, such as excessive harmonic generation from the transmitter. Devices which fail to meet AT&T's TIS requirements may have an efficient antenna, but the receiver sensitivity is compromised by self-interference, such as noise entering the antenna from within the device itself.

In short, the antenna and its complex interaction with the wireless device is part of every radiated measurement a device is subjected to during the certification process and will influence the measurement results.

6.1. Using a Certified Radio Module

For obvious reasons, it is important to begin any product design with a radio module that has already been certified. The certified module, when connected to a correctly implemented “typical” antenna, will provide acceptable performance in both receive and transmit modes.

6.2 Transmit Mode Failures

Assuming the radio module is certified and capable of generating the appropriate amount of RF power, transmit mode failures are typically caused by low antenna efficiency or degraded return loss (which appears as low efficiency due to the

Antenna Fundamentals Technical Brief


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