Quantifying Landed Unit Cost Penalties in Global Cellular Deployments
Landed cost penalties in cellular deployments compound through regional certification surcharges, carrier profile fees, tariff codes and roaming airtime multipliers.
Harmonic Attenuation Filtering
Meaning
Electromagnetic suppression involves the use of electronic components to block unwanted signals that are multiples of the desired operating frequency. Harmonic attenuation filtering is the process of removing these high-frequency components before they are radiated by the antenna. This prevents the transmitter from causing interference on other frequency bands that might be used by different services.
Filter Performance
Low-pass filters are the most common tools used to achieve the necessary reduction in spurious emissions. The effectiveness of harmonic attenuation filtering is measured by how many decibels the unwanted signals are reduced relative to the carrier signal. A filter with a high rejection rate ensures that the second and third harmonics do not exceed the limits set by regulatory agencies like the FCC.
Circuit Integration
Placing these filters as close as possible to the power amplifier minimizes the chance of harmonics leaking into other parts of the system. Effective harmonic attenuation filtering requires careful attention to the grounding and shielding of the printed circuit board. If the layout is poor, the signals can bypass the filter through parasitic capacitance or mutual inductance.
Regulatory Compliance
Certification laboratories test every wireless device to ensure it does not pollute the radio spectrum. Harmonic attenuation filtering is essential for passing these tests and obtaining the legal right to sell the product. A device that fails these emissions tests must be redesigned with better shielding or more aggressive filtering stages.
This verification ensures that the growing number of connected devices can coexist without degrading the performance of public safety radios or other critical communication links.