Bandwidth Enhancement of Planar Slot Antenna Using Complementary Source Technique for Millimeter-Wave Applications

Traditional coplanar waveguide (CPW)-fed planar slot antennas are inherently narrow in bandwidth. Widening open-ends of the slot and adding parasitic elements are popular techniques for bandwidth enhancement. An alternative approach is to apply complementary sources. In this paper, a new stacked structure of complementary antenna is proposed which utilizes a traditional CPW-fed slot antenna to act as a magnetic source and a parasitic dipole located across the slot to act as an electric source. This antenna array, fabricated on generic microwave substrate with simple plated-through-hole, printed-circuit technology, the measured impedance bandwidth can cover from 55 to 67 GHz for VSWR ≤ 3.0. It achieves a maximum measured gain of 12.2 dBi at 65 GHz and above 10.0 dBi in the passband from 56 to 67 GHz for 60-GHz application.