A Novel Dual-Band Reconfigurable Square-Ring Microstrip Antenna

Abstract

Abstract-A novel compact dual-band reconfigurable square-ring microstrip antenna is presented. The tuning is achieved using a single varactor diode connected to a small square patch attached to an inner corner of the square-ring. The square patch perturbs the symmetry and splits the two degenerate modes to create dual-band operation. The frequency ratio in the range of 1.04 to 1.4 can be achieved by the proper selection of the square patch size. The lower resonance frequency can be further decreased by loading the square patch at its corner by a reverse biased varactor diode. The diode has almost no effect on the upper resonance frequency. This technique is used to implement an electronically tunable dual-band antenna on FR4 material with ε r = 4.5 and 1.5 mm thickness. The size of the ring, the square patch, and the varactor used, are selected to yield a fixed upper resonance frequency at about 1.93 GHz. The resulting lower resonance frequency is tuned from 1.37 to 1.7 GHz in the voltage range from 0 to 30 V, respectively. The measurements agree well with simulation results.

Meandered Slot and Slit Loaded Compact Microstrip Antenna With Integrated Impedance Tuning Network

“…Compact operation of microstrip antennas can be obtained by meandering the radiating patch [1,5,6]. A slot and slit loaded rectangular microstrip antenna with dual-frequency operation has recently been reported [3,6,16,18]. The TM01 and TM30 modes are similar and have parallel polarization planes in these antennas.…”

An Approach to Equivalent Circuit Modeling of Rectangular Microstrip Antennas

“…The generated modes in the wideband E-shaped antenna [16][17][18] are basically perturbed versions of the modes that are excited in conventional RMPAs and the radiating modes are modeled as the series connection of parallel resonant sections [15]. The slots on the patch contribute to perturbations in radiating modes which can expand the antenna bandwidth or generate dual-band functionality [16][17][18][19][20][21][22][23]. …”

Dual Band Coplanar Capacitive Coupled Microstrip Antennas With and Without Air Gap for Wireless Applications

“…However, the use of air gap increases the height/volume of the antenna which is undesired in several (compact) applications [15]. Therefore, a design that uses small air gap for the similar antenna design is reported earlier [13] There are several microstrip patch antennas available in literature, which operate at dual resonant frequencies [14,[18][19][20][21][22][23][24][25][26][27][28][29][30]. For example antenna reported in [18] uses stacked configuration [18], whereas geometry presented in [19] uses suspended configuration (with air gap) [19].…”