Patch antenna fed by shorted coplanar microstrip line

A novel dual-frequency patch antenna fed by a coplanar microstrip line is presented. By embedding a shorting pin in the microstrip feed line, the proposed antenna is capable of operating at two distinct modes with different radiation characteristics: omnidirectional shorting-pin-loaded patch mode and broadside regular patch mode. In addition, the frequency ratio of the two resonant frequencies is also tunable in the range 3.7-2.7 by loading an additional slot in the microstrip patch.