MODULATED METAMATERIAL MICROSTRIP PATCH ANTENNA FOR MULTIFUNCTIONAL APPLICATIONS

Abstract

With the development of wireless communication, the demand of compact size, light weight, lower costing and low profile antenna is on an increase. Thus, planar microstrip antennas are much desirable for modern day systems. In addition, the ground plane, the substrate or the radiating part of an antenna needs to be engineered artificially to provide better antenna designs in terms of electrical performance, size reduction along with other physical modifications as required for various applications. Metamaterial proves to be good candidate for enhancing the limitations of patch antenna like low gain, narrow bandwidth, low power, spurious radiation etc. In this report, the attention is focused on the multifunctional applications of modulated metamaterials microstrip patch antenna. The effect of loading the microstrip antenna with metamaterial is analyzed in detail, in this dissertation work. Microstrip patch antenna is designed in HFSS, based on the Artificial Magnetic Conductor structure. A rectangular microstrip patch antenna which is loaded with Metasurface both on patch as well as on ground plane is studied. Radiation performance enhancement results in miniaturization of patch antenna. In addition, other parameters such as reflection cpoefficient, gain, bandwidth and efficiency are also observed for all the cases. High impedance ground planes are studied and design of a High Impedance Surface (HIS) unit cell is carried out in ANSYS HFSS (High Frequency Electromagnetic Field Simulation), with Floquet port and Bloch boundary conditions. Modal analysis and eigenmode analysis is done for the same. High impedance behavior of a number of Unit cells is analyzed. Various Modulated metasurface structures has been designed for Radar Cross Section Reduction of Microstrip Patch Antenna. Modulated metasurface is designed keeping in mind the fact that the field which is being reflected is not in phase (or 180 deg in phase) for a certain range of frequencies resulting in destructive interference in this range. Modulation can be achieved with three parameters: ’a’(size of patch), ’f’(angle of rotation of patch), a/a’(size of patch relative to the size of whole unit cell). Modulation has been realized by various combination of these parameters, like one with changing only ’a’, one with changing only ’f’ and one with changing both ’a’ and ’f’. Remarkable Monostatic RCS reduction and gain enhancement has been observed for all designs. Different multiband microstrip antenna for wireless applications are designed under this dissertation work. A dual and triple band planar antenna has been designed by loading Complementary i Split ring resonator(CSRR) structures on either patch or ground. One triple band microstrip antenna loaded with composite right/left handed metamaterial is also designed and its Zeroth Order resonance behavior is analyzed. Also, one compact Ultra Wideband microstrip antenna using metamaterial is designed which has a mesh shaped patch and patterned ground plane. The same is analyzed for different substrate material and its thickness. At last, gain enhancement of the patch antenna using metamaterial is analyzed. By etching different CSRR structures on ground plane, performance of the antenna is observed. For verifying the simulated results, the prototypes has been fabricated in the lab and the measurements are done in anechoic chamber.