Design and Testing of a Simple, Compact Antenna with Reconfigurable Broadside and Monopole-Like Patterns

A compact antenna with broadside and monopole-like pattern reconfigurability is presented. Its radiating elements are linearly polarized and consists of a magnetic dipole and an electric monopole. A capacitively loaded loop and two rectangular strips, one driven and one parasitic, serve as a magnetic near-field resonant parasitic radiator. The broadside pattern is generated by the magnetic radiator; the electric monopole radiates the monopole-like pattern. A coax-fed structure is developed with only two p-i-n diodes integrated into it that dynamically controls the excitation of either the magnetic or the electric radiator. A prototype was fabricated and tested. The measured results are in reasonable agreement with their simulated ones. The antenna is impedance matched within an overlapping operational fractional bandwidth of 3.8%; the combination of its radiating elements is compact with ka_rad = 0.69. The realized gain value of the broadside pattern at boresight is 7.1 dBi and the null of the monopole-like pattern is over -28 dBi deep. The prototype is an attractive candidate for applications in many space-limited wireless systems that require reconfigurable broadside and monopole-like performance characteristics.