From the reflection coefficient of the equivalent waveguide feed one can determine the frequency band where minimum energy will be lost due to unwanted radiation from the cavity sides. The electromagnetic bandgap (EBG) performance of the cavity structure between the upper conducting surface in which the slot is etched, and the ground plane at the bottom of the reflector, is investigated using an equivalent waveguide feed in the place of a half-wavelength section of the slot antenna. The slot antenna radiates above a closely spaced artificial magnetic conducting (AMC) reflector consisting of an array of rectangular patches, a substrate and an electric ground plane. It still retains advantages of low-profile, low fabrication cost, and easy integration with planar circuits.Ībstract: A low profile coplanar waveguide (CPW) fed printed slot antenna is presented with uni-directional radiation properties. The proposed antenna exhibits low cross polarization level and high front to back ratio. Compared with those of a previously presented SIW cavity-backed slot antenna, fractional impedance bandwidth of the proposed antenna is enhanced from 1.4% to 6.3%, its gain and radiation efficiency are also slightly improved to 6.0 dBi and 90%, and its SIW cavity size is reduced about 30%. This design method has been validated by experiments. These two hybrid modes, whose dominant fields are located in different half parts of the SIW cavity, are two different combinations of the and resonances. Bandwidth enhancement is achieved by simultaneously exciting two hybrid modes in the SIW-backed cavity and merging them within the required frequency range.
#MICROSTRIP ANTENNA THEORY AND APPLICTION S. S. ZHANG PATCH#
To have a greater directivity, an array can be formed by using these patch antennas.Abstract: A bandwidth enhanced method of a low-profile substrate integrated waveguide (SIW) cavity-backed slot antenna is presented in this paper. The radiation pattern of a microstrip or patch antenna is shown above. It has low radiation power and narrow frequency bandwidth. The radiation pattern of microstrip or patch antenna is broad. When the antenna is excited, the waves generated within the di-electric undergo reflections and the energyis radiated from the edges of the metal patch,which is very low. The following image shows a micro-strip or patch antenna. Usually, the patch or micro-strip is choosen to be square, circular or rectangular in shape for the ease of analysis and fabrication. The radiating element and feed lines are placed by the process of photo-etching on the di-electric material. Micro strip antenna consists of a very thin metallic strip placed on a ground plane with a di-electric material in-between. Construction & Working of Micro strip Antennas The patch antennas are popular for low profile applications at frequencies above 100MHz. These are very low size antennas having low radiation. A metal patch mounted at a ground level with a di-electric material in-between constitutes a Micro strip or Patch Antenna. Micro strip antennas are low-profile antennas.
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