Multifunctional Antennas and Arrays for Wireless Communication Systems. Группа авторов. Читать онлайн. Newlib. NEWLIB.NET

Автор: Группа авторов
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Техническая литература
Год издания: 0
isbn: 9781119535072
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target="_blank" rel="nofollow" href="#ulink_01ccacd2-d045-5b41-9c85-18e2dd40c462">Figure 1.1 The importance of antenna in a wireless communication system.

      Antenna performance parameters can be categorized into two groups: circuit parameters and radiation parameters. Circuit parameters refer to the impedance matching properties such as reflection coefficient magnitudes (|Sii|) and isolation (|Sij|) between the antenna ports. Antenna radiation parameters refer to radiation patterns, gain, directivity, antenna efficiency, polarization, effective length and effective aperture, antenna temperature, etc. Readers should refer to the well‐known text book by C. A. Balanis, Antenna Theory: Analysis and Design (Fourth Revised edition), Wiley publications [1] for detailed discussion and learning about these antenna performance parameters.

Schematic illustrations of some antenna types generated through Antenna Design Kit in Ansys Electronic Package.

Schematic illustrations of antenna performance shown using (a) reflection coefficient magnitude (S11, dB) and (b) 3D gain radiation pattern. Schematic illustrations of (a) a frequency tunable concentric circular microstrip patch antenna along with varactor diode placement locations, (b) photograph of the fabricated control feed network, (c) measured frequency tunable response for both feed ports, and (d–g) comparison between the measured and simulated gain radiation patterns for 4 V bias voltage which corresponds to 1.36 GHz tunable band for horizontal linear, vertical linear, RHCP, and LHCP, respectively.

      Source: Babakhani and Sharma [2].

      The frequency response with bias voltage variation is shown in Figure 1.4c. With 0 V bias, the antenna resonates at the lowest frequency (1.17 GHz). Similarly, with 12 V bias, the antenna operates at 1.58 GHz. Thus, this antenna provides frequency tunability between 1.17 and 1.58 GHz which corresponds to 30% tunability. By applying bias voltage to two varactors each along with one feed point, vertical and horizontal linear polarizations are achieved. Similarly, applying the same bias voltage to all the varactors and exciting both feed points in ±90° time phase difference, right hand (RH) or left hand (LH) circular polarization is obtained. Measured and simulated