Design of frequency-reconfigurable rectangular slot ring antennas

Summary form only given. This paper presents the concept of a frequency-reconfigurable rectangular ring slot antennas fed by a single slotline or CPW line. The reconfiguration is carried out by switching in or out appropriate slot-line lengths in a rectangular slot-ring antenna. An example of this configuration for a two-frequency antenna is shown. The total periphery of the outer loop determines the lower of the two frequencies; and the inner loop determines the higher of the two reconfigurable frequencies. The concept can be extended to a multiple frequency reconfigured antenna by adding more slotline segments to the configuration shown. Full-wave EM simulations using HP´s Momentum have been carried out to demonstrate the feasibility of the proposed concept. A sample antenna has been designed with two operating frequencies being 3.0 and 8.3 GHz. The two radiation patterns are close to each other. It has been found that a single CPW line of about 100-ohm impedance can feed the antennas at both the frequencies. A two-stage quarter-wave transformer is used to connect the antenna to the measurement system. Values of the input match at the two frequencies are - dB and -22 dB respectively.