The resonance frequency formulation for hexagonal microstrip antenna using its equivalence to circular microstrip antenna is proposed for fundamental and higher order modes and it gives closer agreement with simulated results. The compact variations of H-shaped microstrip antennas in its fundamental mode are proposed. The dual band H-shaped microstrip antenna realized by cutting a U-slot or pair of rectangular slots is proposed. They give dual band response with broadside radiation pattern. To understand the mode introduced by the slot, the analysis for pair of rectangular slot cut H-shape antennas by studying their surface current distributions out over a wide frequency range is carried out. It was observed that the rectangular slots do not introduce any mode but they alters the higher order mode resonance frequency of the patch and along with the fundamental mode realizes dual frequencies. By studying the surface current distributions, a formulation of the resonant length for the slot mode is proposed. The frequencies calculated using them agrees well with the simulated results with an error of less than 5% over the entire slot length range.

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Circular microstrip antenna H-shaped microstrip antenna Compact H-shaped microstrip antenna dual band H-shaped microstrip antenna