March 2019
Intermediate to advanced
288 pages
9h 24m
English
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7Other Types of Low‐cost Smart Antennas
7.1 Introduction
In this chapter, some other types of low‐cost smart antennas are presented. These include the multi‐beam dielectric lens, retrodirective array, pattern‐reconfigurable FP resonant antenna, beam‐switching antennas using the AFR, and multi‐beam antennas based on passive beamforming networks. The dielectric lens, FP resonant antenna, and AFR provide low‐cost solutions to achieving high directivity and multiple beams (or beam‐switching) without resorting to the use of a large number of active radiating elements, thus they are attractive solutions to microwave and mm‐wave smart antennas, such as smart antennas for 5G massive MIMO base stations, mobile satellite communications, and automotive radars. Multibeam or beam‐switching antennas can also be achieved by using antenna arrays integrated with low‐cost passive beamforming networks such as the Butler matrix, Nolen matrix, and Rotman lens. The retrodirective array determines the angle of arrival of the incident signal and re‐transmit the signal back without using any phase shifters, leading to a significant reduction in the cost of the antenna system. In the following sections, the principles and design techniques of these low‐cost smart antennas are explained and examples from recent reported designs are presented.
7.2 Lens Antennas
7.2.1 Lens Antenna Basics
A lens antenna is a microwave antenna in which an antenna or array antenna is placed in front of a dielectric lens. The lens ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.