In this paper, a high-gain THz antenna array is presented. The array uses a polyimide substrate with a thickness of 10 μm, a relative permittivity of 3.5, and an overall volume of 2920 μm × 1055 μm × 10 μm, which can be employed for THz band space communication and other interesting applications. The dual-band single-element antenna is designed in four steps, while operating at 0.714 and 0.7412 THz with −10 dB bandwidths of 4.71 and 3.13 GHz, providing gain of 5.14 and 5 dB, respectively. In order to achieve a high gain, multiple order antenna arrays are designed such as the 2 × 1 antenna array and the 4 × 1 antenna array, named type B and C, respectively. The gain and directivity of the proposed type C THz antenna array are 12.5 and 11.23 dB, and 12.532 and 11.625 dBi at 0.714 and 0.7412 THz, with 99.76 and 96.6% radiation efficiency, respectively . For justification purposes, the simulations of the type B antenna are carried out in two simulators such as the CST microwave studio (CSTMWS) and the advance design system (ADS), and the performance of the type B antenna is compared with an equivalent circuit model on the bases of return loss, resulting in strong agreement. Furthermore, the parametric analysis for the type C antenna is done on the basis of separation among the radiating elements in the range 513 to 553 μm. A 64 × 1 antenna array is used to achieve possible gains of 23.8 and 24.1 dB, and directivity of 24.2 and 24.5 dBi with good efficiencies of about 91.66 and 90.35% at 0.7085 and 0.75225 THz, respectively, while the 128 × 1 antenna array provides a gain of 26.8 and 27.2 dB, and directivity of 27.2 and 27.7 dBi with good efficiency of 91.66 and 90.35% at 0.7085 and 0.75225 THz, respectively. All the results achieved in this manuscript ensure the proposed design is a feasible candidate for high-speed and free space wireless communication systems.

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Design and Analysis of Dual-Band High-Gain THz Antenna Array for THz Space Applications

In this study, unwanted additional resonances are analyzed and a method is developed to eliminate them for wideband offset dual reflectarray antenna at sub-millimeter waves. In the terahertz range, the additional resonances can usually be generated within the target bandwidth, depending on the angle of incidence, which cannot be predicted by the normal incidence characteristics of a reflectarray. To evaluate the effects of the additional resonances, the phase error and element patterns of the reflectarray are checked by using the equivalence principle and full-wave simulation. It is found that the additional resonances result in the performance deterioration of the reflectarray antenna due to undesirable phase variation and element pattern changes. Therefore, a sub-wavelength unit-cell is employed to eliminate the additional resonances so that the phase error and element pattern distortion of the reflectarray elements can be avoided in the target bandwidth even for a large angle of incidence. A reflectarray with the sub-wavelength unit-cell is then designed, fabricated, and measured to show the improved gain and bandwidth performances of the reflectarray demonstrating the validity of the proposed analysis.

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Analysis and Elimination of Unwanted Resonances for Wideband Reflectarray Antenna Design at Sub-Millimeter Waves

Publisher Summary This chapter discusses different types of astronomical antennas. The pattern of the pencil-beam antenna has one main lobe or maximum with a single-output terminal pair or a few main lobes each with its own separate output. The output at a single terminal pair corresponds to one main lobe for only one sense of polarization: linear, circular, or elliptical. The most common antenna used for radio astronomy is the parabolic reflector with the feed horn or dipole located at the parabolic focus. One principal advantage of this antenna is the ease with which the receiver may be coupled to it. The input terminals are at the feed horn or dipole. Operation over a wide range of wavelengths is simple; changing from one band of wavelengths to another requires only the change of the feed. The multi-element interferometer consists of a number of two-element interferometers operating simultaneously. The outputs of all the antenna elements are combined in pairs and recorded at the same time. The result is a system that can complete the aperture synthesis for a given region of the sky in a time shorter than that required by a simple two-element telescope.

W.J. Welch

Papers

1.2. Types of Astronomical Antennas