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How do I select the right frequency band for a new wireless communication system design?

Selecting the right frequency band for a new wireless communication system requires balancing propagation characteristics (path loss, penetration, multipath), available bandwidth, regulatory availability (licensed vs unlicensed, regional allocations), technology maturity (component availability and cost), and market considerations. Lower frequencies (sub-1 GHz: 700 MHz, 900 MHz) offer excellent propagation range (2-20 km with modest power), good building penetration, but limited bandwidth (typically 5-20 MHz channel allocations) and larger antennas. Mid-band frequencies (1-6 GHz: 1.8, 2.4, 3.5, 5 GHz) offer a good balance of range (0.5-5 km), bandwidth (20-100 MHz channels available), reasonable antenna size, and mature technology at low cost. High-band frequencies (24-71 GHz: 28, 39, 60 GHz) offer very wide bandwidth (100 MHz-2 GHz channels) for high data rates but limited range (100-500 m) and no building penetration, requiring line-of-sight or dense small cell deployment. The regulatory framework is equally important: licensed bands (e.g., cellular spectrum at 700 MHz, 1.9 GHz, 3.5 GHz) provide guaranteed interference-free operation but require expensive spectrum licenses. Unlicensed bands (2.4 GHz, 5 GHz, 6 GHz, 60 GHz) are free to use but subject to interference from other users and power limitations.

Category: Component Selection and Comparison

Updated: April 2026

Product Tie-In: All Components

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.

Frequency vs Propagation Tradeoffs

Sub-1 GHz (IoT, LTE Band 71): Range: 5-50 km (rural). Building penetration: excellent. Bandwidth: 5-20 MHz. Use cases: IoT, smart metering, rural broadband, mission-critical communications
1-3 GHz (LTE, Wi-Fi 2.4 GHz): Range: 1-10 km. Building penetration: good. Bandwidth: 10-40 MHz. Use cases: macro cellular, Wi-Fi, industrial wireless, drone links
3-6 GHz (5G mid-band, Wi-Fi 6E): Range: 0.5-3 km. Building penetration: moderate. Bandwidth: 20-100 MHz. Use cases: 5G enhanced mobile broadband, Wi-Fi 6/6E, CBRS private networks
24-40 GHz (5G mmW, LMDS): Range: 100-500 m. Building penetration: poor. Bandwidth: 100 MHz-1 GHz. Use cases: 5G fixed wireless access, dense urban hotspots, backhaul
57-71 GHz (V-band, WiGig): Range: 10-100 m. Atmospheric oxygen absorption at 60 GHz limits range. Bandwidth: 2+ GHz. Use cases: short-range multi-Gbps links, WiGig, cable replacement

Regulatory Considerations

Licensed spectrum (through auction or assignment): guaranteed QoS, no interference from others, but very expensive ($1-10/MHz/pop in many markets). Unlicensed spectrum (ISM, U-NII): free to use, but shared with other users, power-limited (typically 30 dBm EIRP in 2.4 GHz, 36 dBm in 5 GHz), and subject to DFS requirements in some bands. Lightly licensed (CBRS 3.5 GHz): moderate cost, shared with incumbent users (military radar), managed by SAS database.

Frequency Band Propagation Comparison

Free space path loss: FSPL = 20 log(d) + 20 log(f) + 32.45 [dB, d in km, f in MHz]
At 1 km: 900 MHz FSPL = 91.5 dB, 3.5 GHz = 103.3 dB, 28 GHz = 121 dB
Link budget: P_rx = P_tx + G_tx + G_rx - FSPL - losses
Maximum range: R_max at P_rx = receiver sensitivity

Common Questions

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.

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