Meaning of “4/6 GHz” band plan in satellite links When a satellite system is described as operating at “4/6 GHz,” what do these paired frequencies indicate?

Introduction / Context:
Band-pair notation is standard in satellite communications. In C-band systems, “6/4 GHz” or “4/6 GHz” quickly conveys the uplink and downlink allocations. Understanding this shorthand is essential for link budgeting and regulatory coordination.

Given Data / Assumptions:

• C-band fixed-satellite service typically uses ~5.925–6.425 GHz (uplink) and ~3.7–4.2 GHz (downlink).
• Paired bands are separated to ensure adequate isolation between transmit and receive chains.

Concept / Approach:

In common practice, the higher frequency is used for Earth-to-space (uplink) and the lower frequency is used for space-to-Earth (downlink), primarily due to path loss and rain attenuation considerations and to simplify onboard filtering/isolation.

Step-by-Step Solution:

Verification / Alternative check:

ITU tables and operator band plans confirm the 6 GHz uplink and 4 GHz downlink convention for C-band FSS.

Why Other Options Are Wrong:

Reversing the pair contradicts standard allocations; a “mean frequency” is not used; backup interpretation is incorrect.

Common Pitfalls:

Confusing Ku-band and Ka-band pairs; always check whether the convention lists down/up or up/down, but C-band pairing is well-established.

Final Answer:

4 GHz is the downlink and 6 GHz is the uplink frequency