Printed U-shaped slot antennas fed by CPW via inductive coupling

A U-shaped slot antenna fed by a coplanar waveguide (CPW) is developed via inductive parallel-coupling between the uniform CPW and a pair of symmetrical U-slot radiators. The series radiation resistance at resonance is first derived versus varied coupling-section and slot dimensions, thereby facilitating the realization of impedance matching. Then, one CPW-fed U-shaped slot antenna is constructed by introducing a half-wavelength shorted-end CPW opposite to the feeding port. Predicted return losses and E- and H-plane radiation patterns are confirmed by measurement of the fabricated antenna.