Abstract ▼ AI-Helper

The concepts of microstrip antenna dates back to 1950. However, the concern about this field began 1970. Printed circuit microstrip antennas have been extensively investigated for the last two decade. Among the wide variety of radiating element configurations available to a microwave engineer, micro...

The concepts of microstrip antenna dates back to 1950. However, the concern about this field began 1970. Printed circuit microstrip antennas have been extensively investigated for the last two decade. Among the wide variety of radiating element configurations available to a microwave engineer, microstrip patch antenna occupies a unique status, largely because of the ease of its integration with microwave feed circuitry. In most cases, the elements is fed with either a coaxial line through the bottom of the substrate or a coplanar microstrip line. The ease of manufacturing microstrip transmission line has made microstrip line of major importance for microwave circuit. Since microstrip transmission line is used in all the circuits reported here, the design procedure for microstrip is presented first. The diode switch is the basic element for digital diode phase shifter and the varactor is the basic element for continuous phase shifter. The simplest digital phase shifter consists of two SPDT switches that permit either of two paths to be selected for the transmission path. Next is the reflection type phase shifter. When the switch is closed, the plane of reflection is in the plane of the switch. When the switch is opened, the plane of reflection is at the short and the output wave is delayed by Δl. The loaded-line type is more complex than the first two digital phase shifter. The fourth type of digital diode phase shifter is the most complex, high pass low pass phase shifter. The circuit elements are selected so that the T circuit is exactly matched regardless of whether the switched line are in position to form the low pass or the high pass circuit. The circuit provides phase delay in the low pass position and phase advance in the high pass position. Practical microstrip arrays are built on substrates whose thicknesses are typically less than one tenth of the wavelength and resulting bandwidths are only several percent. Radiating elements are easily photo-etched on the surface of a thin dielectric sheet with a ground plane in the other side. The goal of an antenna design is to produce an antenna system which has high efficiency, large bandwidth and controll ability to send wave to wanted direction. Microstrip array antennas can be used to many applications requiring narrow bandwidth, low power and light weight. In this paper, the simplest an analytical description of rectangular microstrip patch utilizes transmission line theory and model, the parallel radiating slots are presented. The design frequency was chosen to be 5.8GHz. Chebyshev array antenna was achieved by unequal power divider and Wilkinson power divider. The ratio of current at each port is 1 : 2.6 : 2.6 : 1 and then side lobe level is less than -30dB. A 4-bit phase shifter is designed and it has phase differences of 22.5˚ step. The radiation range of the antenna's radiation beam direction is up to 30˚. Experimental results are in good agreement with theoretical values. The good agreement between theory and measurements shows that the design theory allows the direct high precision manufacture of compact components without the necessary for additional trial and error adjustment methods. The result can be used to design electrically controllable microwave scanning antennas.

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