A Compact Dual-band Dual-polarized Antenna Based on Modified Minkowski Fractal

Abstract

The polarization of the received signals can be effectively matched regardless of the orientation of the receiving antenna using circularly polarized antennas. A compact printed monopole antenna with a circular ring patch is presented in this paper. The proposed antenna will be able to provide two polarization states: linear and circular. The employment of a modified Minkowski fractal with 1st iteration construction on an open circular ring supports a circularly polarized band having a center frequency of 1.812 GHz and fractional bandwidth (FBW) of 20.033%. The upper band is achieved with a linearly polarized wave having a center frequency of 3.386 GHz and a fractional bandwidth of 11.399%. The proposed antenna is fed by an ungrounded co-planar waveguide (UCPW), enhanced with an impedance transformer to match at 50 Ohms with the characteristic impedance. The ground planes around the feed line are defected by ground structures to improve the antenna gain. The fabrication and measurement of the proposed antenna prototype are presented to validate the theoretical results. Measured results support the theoretical findings well.