A Compact Triband Bow-Tie Slot Antenna Fed by a Coplanar Waveguide

A uniplanar and compact bow-tie slot antenna capable of triband operation is proposed. Design considerations for the three operating frequencies are extensively discussed. Unlike most other multifrequency antennas having their sizes determined by the lower resonant frequency, the size of the proposed antenna is determined by the upper resonant frequency, and thus it is compact in nature. The middle and lower operating frequencies are obtained by inserting two metal strip pairs near the ends of the bow-tie slot without increasing the overall antenna area. Measured reflection coefficients are compared to the simulated ones with good agreement, and radiation patterns at the three operating frequencies are broadside and bidirectional and with satisfactorily low cross-polarization levels.