X-band slotted waveguide marine radar antenna on ship, 8 - 12 GHz. The antenna radiates a narrow vertical fan-shaped beam of microwaves, scanning the entire 360° water surface around the ship with each rotation.
Properties Of A Basic Microstrip Patch A microstrip or patch antenna is a low-profile antenna that has a number of advantages over other antennas: it is lightweight, inexpensive, and electronics like LNA’s and SSPA’s can be integrated with these antennas quite easily. While the antenna can be a 3. The L-shaped narrow slots are introduced at two corners of a rectangular patch antenna for multifrequency operation. The performance of the modified patch is obtained from the simulation and modeling using Ansoft HFSS tool. Rectangular patch antenna with achievable impedance bandwidth of 20% has been demonstrated 7. By using the shorting pins or shorting walls on U-shaped patch, U-slot patch, or L-probe feed patch antennas, wideband and dual band antenna with electrically small in size have been reported in 8,9. Other techniques involves employing multilayer.
As circular polarization etc.Microstrip patch antenna have some disadvantages also like surface wave excitation, narrow bandwidth etc.But bandwidth of a microstrip patch antenna can be improved by various methods like cutting U-slot 4, increasing the substrate height, decreasing ∈? of substrate etc. Lingjian Li and Zhirun Hu, A wideband linear U-slot microstrip patch antenna array for wireless application, International Journal of Electronics, 96, 7, (755), (2009). Steven Steven.
Cross section of similar marine radar antenna, showing slots in waveguide.
Construction of a similar antenna, which can radiate either linearly or circularly polarized microwaves from alternate sides. The linearly polarized waves from the righthand waveguide are converted to circular polarization by a filter.
Slotted array UHF television broadcasting antenna
Overview of Microstrip Antennas. Also called “patch antennas” One of the most useful antennas at microwave frequencies (f 1 GHz). It usually consists of a metal “patch” on top of a grounded dielectric substrate. The patch may be in a variety of shapes, but rectangular and circular are the most common. Microstrip line feed Coax feed.
Microstrip Patch Antenna Design Equations
A slot antenna consists of a metal surface, usually a flat plate, with one or more holes or slots cut out. When the plate is driven as an antenna by a driving frequency, the slot radiates electromagnetic waves in a way similar to a dipole antenna. The shape and size of the slot, as well as the driving frequency, determine the radiation pattern. Often the radio waves are provided by a waveguide, and the antenna consists of slots in the waveguide. Slot antennas are usually used at UHF and microwave frequencies, where the waves are usually conducted by waveguide, so a slot in the waveguide makes a simple antenna. They are often found in standard desktop microwave sources used for research purposes. A slot antenna's main advantages are its size, design simplicity, and convenient adaptation to mass production using either waveguide or PC board technology.
An antenna consisting of multiple parallel slots in a waveguide is a widely used array antenna which radiates a narrow fan-shaped beam of microwaves at right angles to the waveguide, with its narrow axis in the plane of the waveguide and its wide axis perpendicular to the waveguide. Multiple slot versions are widely used in radar antennas, particularly marine radar antennas on ships, and for the sector antennas used for cell phone base stations.
Due to Babinet's principle a slot in a waveguide has the same radiation pattern as a driven rod antenna whose rod is the same shape as the slot. This can be used to determine the radiation pattern using calculations for a more conventional antenna.
The slot antenna was invented in 1938 by Alan Blumlein, while working for EMI. He invented it in order to produce a practical type of antenna for VHF television broadcasting that would have horizontal polarization, an omnidirectional horizontal radiation pattern and a narrow vertical radiation pattern.[1][2]
See also[edit]
- Microwave Radiometer (Juno) (has a slot array antenna)
- RIMFAX (radar for Mars rover has slot antenna design)
Patch Antenna
References[edit]
- ^Blumlein, Alan (1938-03-07), 'Improvements in or relating to high frequency electrical conductors or radiators', British patent no. 515684
- ^Burns, Russell (2000). The life and times of A.D. Blumlein. Institution of Engineering and Technology. ISBN0-85296-773-X.
External links[edit]
- 'Slot Antennas'. Antenna Theory.
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