tailieunhanh - Fundamentals of Engineering Electromagnetics - Chapter 9

Trong chương 8, một cái nhìn tổng quan về thuật ngữ cơ bản ăng-ten và ăng-ten tài sản đã được đưa ra, bao gồm cả một cuộc thảo luận về khái niệm được phổ biến cho tất cả các ăng-ten. Trong chương trình bày, thảo luận tập trung vào các thuộc tính cụ thể của một số các lớp học đại diện của ăng-ten thường được sử dụng. Chúng bao gồm microstrip ăng-ten, ăng-ten băng thông rộng, các mảng theo từng giai đoạn, ăng-ten đi du lịch và bị rò rỉ sóng, và ăng-ten khẩu độ. Tất nhiên, trong một. | 9 Antennas Representative Types David R. Jackson Jeffery T. Williams and Donald R. Wilton University of Houston Houston Texas In Chapter 8 an overview of basic antenna terminology and antenna properties was given including a discussion of concepts that are common to all antennas. In the present chapter the discussion is focused on the specific properties of several representative classes of antennas that are commonly used. These include microstrip antennas broadband antennas phased arrays traveling and leaky-wave antennas and aperture antennas. Of course in a single chapter it is impossible to cover all of the types of antennas that are commonly used or even to adequately cover all of the design aspects of any one type of antenna. However this chapter should provide enough information about the five types of antennas that are discussed here to allow the reader to obtain a basic overview of the fundamental properties of these major classes of antennas and to see how the properties vary from one class to another. The references that are provided can be consulted to obtain more detailed information about any of these types of antennas or to learn about other types of antennas not discussed here. . MICROSTRIP ANTENNAS . Introduction Microstrip antennas are one of the most widely used types of antennas in the microwave frequency range and they are often used in the millimeter-wave frequency range as well 1-3 . Below approximately 1 GHz the size of a microstrip antenna is usually too large to be practical and other types of antennas such as wire antennas dominate. Also called patch antennas microstrip patch antennas consist of a metallic patch of metal that is on top of a grounded dielectric substrate of thickness h with relative permittivity and permeability sr and jir as shown in Fig. usually jir 1 . The metallic patch may be of various shapes with rectangular and circular being the most common as shown in Fig. . Most of the discussion in this section .