Analysis of Slot Cut Triple Band Rectangular Microstrip Antennas

More frequently multi-band micro strip antenna is realized by cutting U-slot, rectangular slot, etc, at an appropriate position inside the patch. While designing them in given frequency range, half wave or quarter wave length approximation of slot length is used. However this design approach does not give closer results for wide range of slot dimensions and their position inside the patch. In this paper, an extensive analysis to study the triple band response in rectangular slot or U-slot or their combinations, cut rectangular micro strip antenna is presented. The slot reduces the resonance frequencies of higher order orthogonal modes, to yield triple frequency response. The slot also modifies surface current distributions at higher order modes to yields broadside radiation pattern over three frequencies without any variations in the directions of principle planes. The proposed analysis will help in understanding the functioning of slot cut multi-band micro strip antennas and will help to design them in given frequency band.