Communication Basics #24 Worked Example: Microwave Link Budget

Instructor: Dr. Süleyman Burak ÇELİK

Sixth midterm preparation video in the Communication Basics series. We walk through a full microwave link budget step by step in light mode. We have a 1-mile microwave link operating at 1 GHz. Transmitter output power is 1 dBm, both transmit and receive antennas have 25 dBi gain, and cabling loss is 2.2 dB on each end. We solve five parts: which band for longest path, which for highest bandwidth, received signal level (RSL), fade margin given −70 dBm receiver sensitivity, and which design is better. Along the way we build the link budget from scratch: block diagram showing where each dB enters or leaves, free-space loss formula FSL = 96.6 + 20 log D + 20 log F (D in miles, F in GHz), and full substitution RSL = Po − Lctx + Gatx − Lcrx + Garx − FSL. At 1 mi / 1 GHz: FSL = 96.6 dB, RSL = −50 dBm. Fade margin = RSL − receiver threshold = −50 − (−70) = 20 dB. We close with a complete link budget table and three takeaways: FSL dominates, antenna gain + low cable loss are your design levers, and always design with at least 10–20 dB fade margin. Part of the AcEdumy Communication Basics series.