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2 years ago in Electrical Engineering By Virat
I keep getting confused by the definitions of radiation efficiency, total efficiency, and realized gain in my antenna measurements. Can you clarify how they differ and what each actually tells me about my design?
In my simulation reports, I see radiation efficiency (η_rad), total efficiency (η_total), and realized gain (G_realized) as separate outputs. I understand that mismatch (S11) affects some but not all of these. For my 4G antenna prototype, which metric is the most important indicator of real-world performance in a handset? If my radiation efficiency is high (say 90%) but my realized gain is low, where is the loss most likely occurring, and how do I systematically debug it?
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By Sumitra M Answered 1 year ago
Think of these as a chain of cascaded losses. Radiation Efficiency (η_rad) accounts for ohmic/dielectric losses only—it's the ratio of radiated power to power accepted at the antenna's terminals. Total Efficiency (η_total) includes both ohmic losses and mismatch loss: η_total = η_rad * (1 - |S11|²). Realized Gain then takes the total efficiency and applies the antenna's directivity pattern: G_realized = Directivity * η_total. If your η_rad is 90% but realized gain is low, the culprit is almost certainly a combination of poor impedance match (high S11) and/or a very low directivity pattern (e.g., a poorly designed omnidirectional antenna). My debugging flow is: 1) Optimize S11 first, 2) verify material losses aren't high (check η_rad), 3) then shape the pattern for the needed directivity.
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