Over the Air Isotropic Sensitivity Verification for Multi Operator Cellular Hardware
Total isotropic sensitivity verification requires spherical anechoic testing to capture housing detuning and active internal EMI desense missed by conducted tests.
Harmonic Interference
Meaning
Unwanted signals generated at integer multiples of the fundamental operating frequency of a transmitter. Harmonic interference occurs because of non linearities in the power amplifier or other active components in the signal chain. It can disrupt other radio services operating in higher frequency bands and must be suppressed to meet regulatory standards.
These emissions are a natural byproduct of the signal amplification process in any radio system.
Filtering Strategy
Low pass or band pass filters are placed after the power amplifier to attenuate these higher frequency components. Effective suppression of harmonic interference depends on the rejection characteristics of the filter and the layout of the circuit board to prevent signal bypassing.
System Impact
High levels of these spurious emissions can desensitize the receiver of the same device or nearby hardware. When harmonic interference falls into a protected frequency band, such as those used for GPS or aviation, the product will fail the certification process immediately.
Measurement Technique
Spectrum analyzers are used during the design phase to identify the amplitude of each harmonic relative to the carrier signal. This assessment confirms that the transmitter operates cleanly across its entire power range and does not produce excessive noise.