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Low-cost Smart Antennas
book

Low-cost Smart Antennas

by Qi Luo, Steven Shichang Gao, Chao Gu, Wei Liu
March 2019
Intermediate to advanced content levelIntermediate to advanced
288 pages
9h 24m
English
Wiley
Content preview from Low-cost Smart Antennas

3Electronically Steerable Parasitic Array

3.1 Introduction

A parasitic array antenna consists of a driven element and several parasitic elements [1]. The driven antenna is the only active radiating element, and the RF energy is distributed from the driven element to parasitic elements by electromagnetic coupling. One of the well known parasitic arrays is the Yagi‐Uda antenna, which uses parasitic elements to obtain high directivity. There is another type of parasitic array antenna called the electronically steerable parasitic array (ESPAR). This type of parasitic array antenna applies tunable components to parasitic antenna elements to obtain reconfigurable radiation patterns. Figure 3.1 shows a typical example of a seven‐element ESPAR antenna.

Schematic of the typical seven-element ESPAR antenna with lines indicating parasitic elements, driven elements, and tunable reactance load.

Figure 3.1 Configuration of the typical seven‐element ESPAR antenna [2].

As shown in Figure 3.1, the element located at the center of the ESPAR antenna is the only active element connected to the RF front end. This active element is surrounded by a number of parasitic elements. The parasitic elements are loaded by electronically tunable components such as sliding loads, PIN diodes, varactors, and MEMS switches. The tunable loads can be adaptively controlled by a DSP. When performing the beamforming, the reactance loads of the parasitic array antennas are adjusted to perform the weighted signal synthesis. Since RF energy is distributed from the ...

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Publisher Resources

ISBN: 9781119422778Purchase book