Slit Cut Circular Microstrip Antenna for Multiband Response

Dual frequency configuration of a circular microstrip antenna embedded with slits fabricated on a thinner substrate was reported which gave dual band operation at 1.64 and 1.89 GHz of frequencies with broadside radiation pattern. On the other hand, a clear description of resonance modes of slit cut circular microstrip antenna that not only results in multiband operation was not given. In this paper, a detailed investigation explaining the multiband response of the reported work is presented using resonance curve plots, return loss plots and its surface current distributions. It is observed that dimensions of slits embedded in the given patch antenna modifies the various frequencies modes in such a way that yields multiband response with more than two bands of frequencies. The position and dimensions of the slits with offset feed results in matched input impedances at TM11, TM21 and TM02 modes of the circular patch. These slit dimensions causes the degeneration of these modes that results into dual polarized multiband response.