Tri-band Dual Substrate Aperture Coupled Microstrip Antenna for C, X, and Ku Band Applications

The design work presents a triple Y-fed dual substrate aperture coupled microstrip antenna that operates in C, X, and Ku bands. The overall dimension of the antenna is 50*40*1.894 mm. The antenna has four layers with two dissimilar substrates. A unique triple Y-structured feed line connected to a quarter-wave transformer forms the first layer of the design and shows a greater impact on impedance matching. A superimposed modified defected ground structure is sandwiched between two dissimilar substrates, FR4 and RT5880. The FR4 substrate is placed above the triple Y feed structure over which superimposed DGS is placed to obtain enhanced bandwidth. The third layer is formed by placing the second substrate RT5880 above the ground plane. The dielectric constant of the lower substrate is considered higher than the upper substrate to avoid undesired radiations at unwanted frequencies. A patch with three rectangular slots is placed over the RT5880 substrate for having tri-band characteristics. The patch is excited effectively through the slots in the ground plane thereby enhancing the coupling between the patch and the feed resulting in maximum radiation of RF energy. With this, an enhanced bandwidth of 12.66%, 16.67%, and 7.19% in all three bands is attained. Besides, the proposed design has a gain of 3.265 dBi at the C band, 3.305 dBi at the X band, and 4.385 dBi at the Ku band. The fabricated antenna is tested and the results are compared for both simulated and measured values. The results emphasize that a tri-band antenna can be used effectively in operating frequencies including the 5G wireless application band.