engleski

Modern Design of Multiband Antennas for Mobile

Modern antennas for mobile devices, especially mobile phones, must support multiple wireless services that are transmitted over different frequency bands (e.g. GSM, UMTS, LTE-A, Bluetooth, Wi-Fi, GPS). Although a particular antenna is based on some of the common canonical antenna designs, canonical designs do not often meet the multiband specs that are sought in modern antennas and antenna engineers must resort to creative noncanonical designs that will then achieve their goals. This tutorial will make an overview of the essential theory encompassing microstrip antenna design (as the most popular choice) and discuss innovative solutions in meeting the multiband characteristics of novel antenna designs. The tutorial comprises four parts as described next. The first part will contain an essential microstrip antenna theory. We will review the microstrip antenna concept and structure of common types of microstrip antennas, including a brief discussion on common types of feed. The second part will focus on the design aspects of one of the most popular choices - a rectangular microstrip antenna. The geometry and most popular feed types will be reviewed first, followed by the analytical models that provide satisfactory solutions. Lastly, the notion of the modes of operation and the corresponding resonant frequencies will be introduced. The third part will cover antenna design aspects by means of computer-aided design. Electromagnetic modeling features using one of the commercial EM CAD tools will be presented and then implemented on a few designs of microstrip antennas. For the canonical design case, we will compare the analytical and numerical solution, while for the noncanonical cases, we will pay attention to the powerful features provided by the modern CAD tools (such as structure design tuning, parameter sweep- or optimization- option). In the last part, we will show examples of various multiband antenna designs and interpret the approaches used in them to achieve the design goals. Use of slots in the patch geometry is one of the modern techniques to create multi-resonance behavior of the microstrip antenna and we will discuss the effects of the slot geometry on the antenna resonant frequencies. Moreover, use of shorting pins and diodes, as additional instruments in the modern antenna design, will be illustrated. Lastly, we will show the results of a recent investigation of interpolative computation of the slot dimensions of a rectangular microstrip antenna, that avoids a direct usage of a full- wave EM code, based on a predefined number of reference data samples that were acquired in advance on a reference antenna model.

multiband antennas ; radiation ; CAD ; antenna design

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