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1 year ago in Antenna & RF Design , Electromagnetics , Engineering By Aashima
Why do electrically small meandered dipoles sometimes exhibit negative gain?
Meandered dipoles are used to miniaturize antennas, but I’ve observed cases where their realized gain is negative. I want to understand the electromagnetic and design factors—such as radiation efficiency, impedance mismatch, or current distribution—that cause this phenomenon and how it can be mitigated in compact antenna design.
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By Mobdchttps://phddiscussions.in/user/profile Answered 1 year ago
From my experience designing compact meandered dipoles, I have seen that negative gain usually arises from low radiation efficiency and impedance mismatch. Electrically small antennas inherently store more reactive energy than they radiate, and the meandering increases conductor and substrate losses, further reducing efficiency. I would recommend checking the input match—if much power is reflected, the realized gain drops, sometimes below 0?dBi. Additionally, current distribution becomes uneven in highly folded structures, causing destructive interference in far-field radiation. In practice, careful optimization of meander geometry, substrate choice, and matching network design is essential to mitigate these effects and achieve usable positive gain, even in compact form factors.
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