The C-band frequency range spans from 4 GHz to 8 GHz, corresponding to wavelengths between 3.75 cm and 7.5 cm, positioning it as a core communication resource within the microwave spectrum. This band has become a critical technological foundation for satellite communications, the Internet of Things, meteorology, and other fields due to its robust interference resistance and extensive coverage capabilities.
Recently, our company successfully prototyped the world's first C-band sapphire oscillator. By designing a 5 GHz high-Q sapphire resonator paired with an ultra-low phase noise oscillation circuit, we achieved stable oscillation of the 5 GHz signal. Test waveforms indicate phase noise levels of -157.99 dBc/Hz and -162.96 dBc/Hz at 10 kHz and 100 kHz deviations from the carrier, respectively—the lowest values documented in current literature. This achievement underscores our company's technological leadership in this field.
Key Technical Specifications:
Output Frequency: 5GHz
Phase Noise:
-132.10dBc/Hz@1kHz
-157.99dBc/Hz@10kHz
-162.96dBc/Hz@100kHz
-171.23dBc/Hz@1MHz
-171.11dBc/Hz@10MHz
-169.64dBc/Hz@100MHz
01
Introduction to C-Band Applications
The C-band is one of the microwave frequency bands defined by the International Telecommunication Union (ITU), covering frequencies from 4 to 8 GHz with wavelengths ranging from 3.75 cm to 7.5 cm. Compared to the lower-frequency L-band (1–2 GHz) and S-band (2–4 GHz), the C-band's shorter wavelength enables higher data transmission rates. When contrasted with the higher-frequency X-band (8–12 GHz), its signals suffer less atmospheric attenuation (such as rain fade), making it particularly suitable for communication needs in tropical, rainy regions.
The Core Frequency Band for Satellite Communications
The C-band has been utilized for satellite communications since the 1960s. Notable examples include: the 1962 Telstar satellite achieving the first transatlantic live television broadcast via C-band; and modern satellite television broadcasts (such as CCTV, BBC, etc.) still relying on C-band transponders for stable signal delivery. Its superior resistance to rain fade (over 10 times stronger than the Ku-band) has led to widespread adoption in rainy regions like Southeast Asia and South America.
Global Coverage Solution for the Internet of Things (IoT)
In satellite IoT applications, the C-band stands as the preferred choice for cross-border logistics, environmental monitoring, and similar scenarios due to its mature infrastructure (ground stations, satellite terminals) and lower deployment costs. For instance, the International Maritime Satellite Organization (Inmarsat) utilizes the C-band to deliver 24/7 communication services for ocean-going vessels, achieving signal-to-noise ratios (SNR) exceeding 20 dB—far surpassing low-frequency band solutions.
02
Comparative Analysis with Other Communication Bands
Frequency band | Frequency range | Advantages | Limitations |
L/S band | 1-4GHz | High penetration capability, suitable for urban/forest environments | Narrow bandwidth, low data rate |
C band | 4-8GHz | Resistant to rain fade, wide coverage, mature technology | Susceptible to ground-based microwave interference |
Ku band | 12-18GHz | High data rate, small antenna size | Significant rain attenuation requires additional error correction. |
X band | 8-12GHz | Military-grade confidentiality, high resolution | Equipment costs are prohibitively high. |
For example, in 5G communications, the C-band (3.3–4.2 GHz, as defined in some countries) serves as the core resource within the Sub-6 GHz spectrum, balancing coverage and capacity. Meanwhile, millimeter wave (24 GHz and above) offers higher data rates but has a coverage radius of only about 300 meters.