Spectrum management — which part of the radio spectrum is more crowded? Considering practical allocations and demand across services (broadcast, mobile, satellite, Wi-Fi, radar, etc.), which portion of the radio spectrum is generally more congested?

Introduction / Context:
Spectrum crowding reflects how many services compete for bandwidth within a frequency range. Lower frequencies are especially valuable due to favorable propagation (longer range, better penetration), making them highly sought after for broadcasting and mobile communications. Understanding this helps explain licensing costs and technology choices.

Given Data / Assumptions:

• Comparison between lower-frequency bands (HF, VHF, lower UHF) and higher-frequency bands (microwave and millimetre-wave).
• General real-world usage across countries and standards.

Concept / Approach:
Lower-frequency bands propagate farther with less infrastructure, so regulators historically allocated many essential services there first. As a result, legacy allocations and modern mobile services crowd these bands. High-frequency bands offer more raw bandwidth but require denser infrastructure and have shorter range, so crowding per hertz tends to be less severe historically, although usage is growing. Thus, the lower-frequency portion is typically considered more congested.

Step-by-Step Reasoning:

Verification / Alternative check:
National allocation charts often show tight packing in VHF/UHF, while higher GHz ranges, though valuable, are comparatively less saturated or are partitioned for specialized services.

Why Other Options Are Wrong:

• Higher frequency part: important but historically less congested than sub-GHz/VHF/UHF for wide-area services.
• Both/None: overgeneralize and ignore the long-standing crowding below a few GHz.

Common Pitfalls:
Assuming new 5G mmWave allocations mean “more crowded” overall; despite growth, lower bands remain hotly contested.

Final Answer:
Lower frequency part