23-07-2012, 12:55 PM
Microstrip Patch antenna
[attachment=28472]
Introduction:
In its most fundamental form, a Microstrip Patch antenna consists of a radiating patch on one side of a dielectric substrate which has a ground plane on the other side.
In order to simplify analysis and performance prediction, the patch is generally square, rectangular, circular, triangular, and elliptical or some other common shape.
Advantages:
Low profile (can even be “conformal”)
Easy to fabricate(use etching and phototlithography)
Easy to feed(coaxiale cable, microstrip line etc.)
Easy to use in array or incorporate with other microstrip circuit elements.
Patterns are somewhat hemispherical with a moderate directivity(about 6-8 dB typical)
Limitations:
Low bandwidth( but can be improved by a variety of techniques). Bandwidth of a few percent are typical.
Efficiency may be lower than other antennas. Efficiency is limited by conductor and dielectric losses, and by surface-wave loss.
Low gain.
Extraneous radiation from feeds and junctions.
Poor end fire radiator except tapered slot antennas.
Low power handling capacity.
Characteristics:
Directivity:
In view of the cavity model, the simplified expression for directivity D can be written as-
Gain:
Gain of the patch antenna from the directivity relative to the vertical axis is normally 2 dB.
Bandwidth:
Bandwidth is related as-
where, S= voltage standing ratio,
Q0= unloaded radiation quality factor.
Efficiency:
where, η= efficiency,
Pr= radiated power,
Pt=power dissipated due to conductor loss,
Pd= power dissipated due to dielectric.
Applications:
Microstrip antennas are increasingly gaining popularity for use in wireless application due to their low profile structure.
Some applications of microstrip patch antenna are tabled as below-
Cellular phone & video
Collision avoidance radar
Direct broadcast satellite
Global positioning satellite
GSM & Paging
Personal communication system
Wide area computer networks
[attachment=28472]
Introduction:
In its most fundamental form, a Microstrip Patch antenna consists of a radiating patch on one side of a dielectric substrate which has a ground plane on the other side.
In order to simplify analysis and performance prediction, the patch is generally square, rectangular, circular, triangular, and elliptical or some other common shape.
Advantages:
Low profile (can even be “conformal”)
Easy to fabricate(use etching and phototlithography)
Easy to feed(coaxiale cable, microstrip line etc.)
Easy to use in array or incorporate with other microstrip circuit elements.
Patterns are somewhat hemispherical with a moderate directivity(about 6-8 dB typical)
Limitations:
Low bandwidth( but can be improved by a variety of techniques). Bandwidth of a few percent are typical.
Efficiency may be lower than other antennas. Efficiency is limited by conductor and dielectric losses, and by surface-wave loss.
Low gain.
Extraneous radiation from feeds and junctions.
Poor end fire radiator except tapered slot antennas.
Low power handling capacity.
Characteristics:
Directivity:
In view of the cavity model, the simplified expression for directivity D can be written as-
Gain:
Gain of the patch antenna from the directivity relative to the vertical axis is normally 2 dB.
Bandwidth:
Bandwidth is related as-
where, S= voltage standing ratio,
Q0= unloaded radiation quality factor.
Efficiency:
where, η= efficiency,
Pr= radiated power,
Pt=power dissipated due to conductor loss,
Pd= power dissipated due to dielectric.
Applications:
Microstrip antennas are increasingly gaining popularity for use in wireless application due to their low profile structure.
Some applications of microstrip patch antenna are tabled as below-
Cellular phone & video
Collision avoidance radar
Direct broadcast satellite
Global positioning satellite
GSM & Paging
Personal communication system
Wide area computer networks