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2 years ago in ABDC , AcademicWriting , Matlab By Rachna M

Is the classic transmission line model even useful for an initial rough size of a UWB microstrip patch, given its narrowband assumptions?

 I'm trying to quickly prototype a UWB patch antenna. The standard transmission line model gives me a length and width based on a single resonant frequency and substrate properties. But since UWB patches work by merging multiple closely-spaced resonances, does this single-frequency starting point lead me astray? Should I instead calculate dimensions for the center frequency, the lowest frequency, or is there a modified version of the model that accounts for the broadbanding modifications like slots or tapered feeds from the outset?

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By Buchiramulu Batta Answered 1 year ago

From my rapid-prototyping experience, the standard transmission line model is a necessary but insufficient first step for a UWB patch. Yes, use it to find the resonant length for your center frequency (e.g., ~6.85 GHz), as this gives you the correct physical scale. However, a traditional rectangular patch designed this way will have maybe a 3-5% bandwidth. The key is to then immediately introduce broadbanding perturbations. I use this initial "vanilla" patch as a baseline in my solver, then iteratively add a U-slot, truncate corners, or step-impedance features to lower the Q-factor and excite additional resonances. The model's true value is giving you a correct ε_eff and a rational starting width and length; it tells you where to place your slots, not the final dimensions. Without it, you're optimizing blindly.

 

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