Description
Over the years, many types of antennas have been developed for different purposes. An antenna may be designed specifically to transmit or to receive, although these functions may be performed by the same antenna. A transmitting antenna in general, must be able to handle much more electrical energy than a receiving antenna. An antenna also may be designed to transmit at specific frequencies.
Microstrip antennas are low profile, conformable to planar and nonplanar surfaces, simple and inexpensive to manufacture using modern printed-circuit technology, mechanically robust when mounted on rigid surfaces, compatible with MMIC designs, and when the particular patch shape and mode are selected, they are very versatile in terms of resonant frequency, polarization, pattern, and impedance.
Microstrip antennas consist of a very thin (t λ0, where λ0 is the free-space wavelength) metallic strip (patch) placed a small fraction of a wave-length (h λ0, usually 0.003λ0 ≤ h ≤ 0.05λ0) above a ground plane. The microstrip patch is designed so its pattern maximum is normal to the patch (broadside radiator).This is accomplished by properly choosing the mode (field configuration) of excitation beneath the patch. For a rectangular patch, the length L of the element is usually λ0/3
