University of Twente Student Theses


Control Surface Waves by Modifying Surface Properties of a Microstrip Patch Antenna Array

Louw, S.J.A. de (2017) Control Surface Waves by Modifying Surface Properties of a Microstrip Patch Antenna Array.

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Abstract:In the last couples of decades radar systems changed significantly. Where in the past systems consist of one antenna, and was the signal mostly analogue, are systems nowadays made of many smaller microstrip antennae (placed in an array) and is the signal completely digital after the antennae. This combination gives possibilities to steer the beam by controlling the phase. Low sidelobes are mandatory to suppress reflections from unwanted directions. Therefore errors coming from the antenna pattern should be sufficiently low. In recent years, significant progress is made on miniaturization of receivers, resulting in array systems with receivers per element. Array systems becomes now completely digital and antenna pattern errors are especially due to antenna elements itself, and much less due to other noise sources. By looking at an single radiating element, one can say that the element pattern is caused by parasitic reflections of the Electro-Magnetic (EM) field on junctions or objects in the vicinity of the radiating element. These reflections interfere with the original radiation pattern of the element, influence the sidelobe level of the whole array. Parasitic reflections occur due to fractional conversation of EM energy into propagating waves at angles close to the antenna surface or even along the antenna surface. Such propagating EM waves are also known as surface waves. The surface properties determines how the waves are bounded to the surface, so the wave can be strictly bounded or loosely bounded to the surface. Hence, by controlling the surface waves the reflections will be reduced and therefore the radiation pattern of the array is improved.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:50 technical science in general, 53 electrotechnology
Programme:Electrical Engineering MSc (60353)
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