National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] Compact Microstrip Antenna By Danish Kumar Hotta Roll No: EC Under the guidance of Mr. Rowdra Ghatak

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [2] Introduction The microstrip antenna is a very thin metallic strip, placed a small fraction of a wavelength above a ground plane, separated by a dielectric. Where size, weight, cost, performance, ease of installation, are of primary concern, microstrip antennas are the best solutions.

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [3] Construction and Geometry 2.2 better efficiency, larger B/W. A microstrip patch antenna is a radiating patch on one side of a dielectric substrate, which has a ground plane on the underside. The EM waves fringe off the top patch into the substrate, reflecting off the ground plane and radiates out into the air.

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [4] Types of Microstrip antennas a) Single radiating patches Square, rectangular, dipole, circular, elliptical, triangular, etc. b) Single slot radiator Narrow slot, circular ring slot, wide slot, circular patch slot. c) Microstrip traveling wave antennas Comb, meander line type, rectangular loop type, Franklin – type MTWA. d) Microstrip antenna arrays Consists of series of antennas connected with each other to give better performance.

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [5] Feeding methods a) Microstrip feed Easy to fabricate, simple to match by controlling the inset position and relatively simple to model. b) Coaxial probe feed Easy to fabricate, low spurious radiation; difficult to model accurately; narrow bandwidth of impedance matching. c) Aperture coupling (no contact), microstrip feed line and radiating patch are on both sides of the ground plane, the coupling aperture is in ground plane Low spurious radiation, easy to model; difficult to match, narrow bandwidth. d) Proximity coupling (no contact), microstrip feed line and radiating patch are on the same side of the ground plane Largest bandwidth (up to 13%).

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [6] Criteria for substrate selection a) Possibility for surface-wave excitation b) Effects of dispersion on the dielectric constant and low tangent of the substrate c) Magnitude of copper loss and dielectric loss d) Anisotropy in the substrate e) Effects of temperature, humidity, and aging f) Mechanical requirements: conformability, machinability, solderability, weight, elasticity, etc. g) Cost

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [7] Polarization types Linear polarization Circular polarization

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [8] Bandwidth consideration Narrowband Vs. Broadband Bandwidth measurement

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [9] Design methodology Research Determining substrate Permittivity Bench mark with commercially available antenna Design feed impedance Investigate broad band techniques Design the broadband patch

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [10] Some important structures Rectangular patch Transmission model Cavity model Circular patch

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [11] Conclusion Disadvantages: Relatively low efficiency (due to dielectric and conductor losses) Low power Spurious feed radiation (surface waves, strips, etc) Narrow frequency bandwidth (at most a couple of percent) Relatively high level of cross polarization radiation Applications: Radio and wireless communications, aircrafts, spacecraft and missile.

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [12]

National Institute of Science & Technology Technical Seminar Presentation-2004 Presented By: Danish Kumar Hotta [EC ] [13]