Aperture coupled Wide-Band Micro Strip Antenna Design

Microstrip patch antennas are well suited for integration in to many applications owing to their conformal nature. There are many wide banding techniques used for the MSAs. But many wide banding techniques such as using slots in the patch require an inductive coupled feed (probe feed). But complete planar (2D) processes for manufacturability needs capacitive coupling. Capacitive coupling with coplanar feed network has the drawback that the feed network interferes with the radiation properties of the antenna. So the coupling techniques with the feed lines in the plane other then the antenna are more suitable. Aperture coupled feed and proximity feed are to such feed techniques. Of these, aperture coupled feed which makes use of thick antenna substrates is the most convenient as it has only single ground plane. Apart from this aperture coupling provides a greater radiation pattern symmetry and greater ease of design for higher impedance band width owing to a large number of design parameters. In this type of feed by using multiple patches bandwidths up to 70% are reported(how ever only single patch design is attempted in this project). So the parametric study, design, fabrication and testing of a with wide band aperture coupled antenna has been attempted in this project. And an aperture coupled antenna with 500 MHz band width was designed at 2GHz range thus realizing 25% band width. Band width considerations: In this project, 10 dB return loss band width is considered for design. The 10dB return loss corresponds to a VSWR of 2. Therefore the impedance circle for the antenna has to stay with in the VSWR =2 circle on the smith chart for the desired range of frequencies. So, the entire design problem thus boils down to identify the parameters of the ACMA geometry which control the impedance circle and tune the design parameters accordingly.