Analysis of Uniform and Tapered CPW-fed Zigzag Monopoles Used as Feed Structures for Wide-Slot Radiators

CPW-fed zigzag monopole radiators can be used to excite wide slots etched on the CPW-grounds for gain enhancement purposes, without significantly altering its resonance. The circuit analysis for CPW-fed zigzag monopole acting as a feed to a wide square slot is presented. Later, the uniform zigzag feed is tapered to support a gradual propagation constant modification. In both cases, the zigzag feed is conceived as an array of two constituent monopoles fed from the same source with modified propagation constants. Simulations along with the measured results are provided to validate the theoretical work which showed less than 2% error achieved in the predictions. Measured gains of the radiators are reported at their resonance frequencies, 2.93dB and 3.19dB respectively for the uniform and tapered zigzag feeds, which validates the observation of gain enhancement in this article.