How do I select the right frequency band for a new wireless communication system design?
Frequency Band Selection for Wireless Systems
Frequency band selection is one of the earliest and most consequential decisions in wireless system design because it determines the antenna size, propagation behavior, bandwidth availability, regulatory regime, and component ecosystem for the entire product or network.
Frequently Asked Questions
Why don't we just use low frequencies for everything?
Low frequencies have limited bandwidth availability (the entire band from 30 MHz to 300 MHz is only 270 MHz total, already allocated to hundreds of services). Also, antennas at low frequencies are very large (a quarter-wave antenna at 100 MHz is 0.75 m). The total available bandwidth below 3 GHz is insufficient for the global demand for wireless data. Higher frequencies offer orders of magnitude more spectrum (the 24-71 GHz range alone contains 47 GHz of spectrum, versus 3 GHz total below 3 GHz).
How do I choose between licensed and unlicensed spectrum?
Use licensed spectrum when: quality of service must be guaranteed (medical, safety, financial), the business model can support spectrum costs, and interference cannot be tolerated. Use unlicensed spectrum when: cost is the primary driver, the application can tolerate occasional interference, the deployment is on private property (reducing interference risk), and standards-based equipment (Wi-Fi) provides adequate performance. Many large enterprises are choosing CBRS (3.5 GHz) as a middle ground: private LTE/5G with guaranteed spectrum at moderate cost.
What about satellite frequencies?
Satellite communication uses specifically allocated bands: L-band (1-2 GHz, mobile satcom), S-band (2-4 GHz, mobile, weather), C-band (4-8 GHz, traditional VSAT), Ku-band (12-18 GHz, TV broadcast, broadband), Ka-band (26-40 GHz, high-throughput satellites), and V-band (40-75 GHz, next-generation LEO constellations). These bands are internationally coordinated through the ITU and are shared between satellite and terrestrial services with specific coordination procedures.