Frequency Reconfigurable Compact Multi-Band Printed Monopole Antenna Using Capacitively Loaded Loops

In this paper, a compact microstrip-fed multi-band frequency reconfigurable monopole is realized by utilizing capacitively loaded loops (CLLs) with embedded PIN diodes as loading elements. Depending on the ON / OFF state of the PIN diodes on the CLLs, quad-band / penta-band / hexa-band characteristics can be achieved from the proposed antenna. All the operating bands exhibit quasi-monopolar omni-directional characteristics, with satisfactory gain performance. The proposed multi-band frequency reconfigurable antenna can be deployed for cognitive radio applications, as well as wireless access points or portable hand-held devices.