This paper presents air gap aperture coupled microstrip antenna for dual-band operation over the frequency range of (2.9 to 6.0 GHz). This antenna differs from any other microstrip antenna with their feeding structure of the radiating patch element. Input signal couples to the radiating patch trough the aperture that exists on the ground plane of microstrip feed line. The dual-band achieved by variation of air gap [2 mm to 6 mm] between single patch antenna and aper-ture coupled microstrip antenna. The main advantage of this type antenna is increased the bandwidth of the antenna as compared to a single layered patch antenna. The two resonant frequencies can vary over a wide frequency range and the input impedance is easily matched for both frequencies. The obtain ratios of resonance frequencies are variable from 2.1 GHz to 1.1 GHz with increasing the air gap between single patch and aperture coupled microstrip antenna. The measured return loss [–14 dB] exhibits an impedance bandwidth of 35%. The input impedance and VSWR return loss have been measured with the help of Network analyzer.
K. F. Lee and J. S. Dahele, “Mode Characteristics of Annular-Ring and Circular-Disc Microstrip Antenna with and without Air Gaps,” IEEE Antennas and Propagation Society International Symposium Digest, 1983, pp. 55-58.
C. S. Lee and V. Nalbandian, “Impedance Matching of Dual-Frequency Microstrip Antenna with an Air Gap,” IEEE Transactions on Antenna and Propagation, Vol. 41, No. 5, 1993, pp. 680-682. doi:10.1109/8.222288
P. L. Sullivan and D. Schaubert, “Analysis of an Aperture-Coupled Microstrip Antenna,” IEEE Transactions on Antenna and Propagation, Vol. 34, No. 8, August 1986, pp. 977-984. doi:10.1109/TAP.1986.1143929
D. M. Pozar, “A Reciprocity Method of Analysis for Printed Slot and Slot-Coupled Microstrip Antenna,” IEEE Transactions on Antenna and Propagation, Vol. 34, No. 12, 1986, pp. 1439-1446. doi:10.1109/TAP.1986.1143785
C. Wu, K. L. Wu, Z. Q. Bi and J. Litva, “Accurate Characterization of Planar Printed Antenna Using Finite-Dif- ference Time-Domain Method,” IEEE Transactions on Antenna and Propagation, Vol. 40, No. 5, 1992, pp. 526- 534. doi:10.1109/8.142627
A. Ittipiboon, R. Oostlander, Y. M. M. Antar and M. Cuchaci, “A Model Expansion Method of Analysis and Measurement on Aperture-Coupled Microstrip Antenna,” IEEE Transactions on Antenna and Propagation, Vol. 39, No. 11, 1991, pp. 1567-1574. doi:10.1109/8.102770