Design of Microstrip Antenna with Greater Bandwidth at Frequencies of GHz and THz HUMBERTO CESAR CHAVES FERNANDES, TARCISIO DA SILVA BARRETO AND OTÁVIO PAULINO LAVOR Department of Electrical Engineering Federal University of Rio Grande do Norte - UFRN University Campus Lagoa Nova BRAZIL [email protected], [email protected], [email protected]Abstract: - This paper presents a microstrip antenna with circular patch that operates at a frequency of 1 THz, with a circular opening in the ground plane, resulting in an increase in bandwidth. At GHz frequencies, the circular opening in the ground plane is performed to obtain a wide pass band. Its prototype is built and measurements are compared with simulated data. Results of loss by insertion and radiation patterns in plans E and H are presented. Key-Words: - Circular patch, THz, Bandwidth. 1 Introduction The structure of a conventional microstrip antenna comprises a radiating metal patch, embedded in a grounded dielectric substrate. As an improvement in the switches of the microstrip antenna, various modifications are found in the literature. Recent strategies for increase bandwidth include variations in ground plane size and the shape of the connection between the feed line and the patch [1- 3], as well as the use of PBG structures (Photonic Band Gap). The increase in bandwidth resulting from these factors is subject to decrease the antenna merit factor by decreasing the dielectric constant [4]. In case these PBG structures, the dielectric constant decreases significantly, causing a large shift in frequency for a higher value. Thus, a change in the ground plane becomes interesting, since it has a simpler construction and causes a less displacement of the frequency. At low frequencies, the modified ground plane with curved branches was used to improve bandwidth [5] and the truncated plane was used in design of UWB antenna (Ultra Wide Band) [6, 7]. The CSRR (Complementary Split Ring Resonator) was also used in the ground plane in antennas for UWB applications [8]. Other modifications had been made in the radiating element as in [9-11]. At high frequencies, microstrip antennas have been well reported. By example, in [12], it is presented a new supply technique using a waveguide transformer. Other studies are described in [13-15]. In this paper, it proposes a microstrip antenna with circular patch designed for the frequency of 1 THz. A circular opening is made in the ground plane in order to obtain better results for the bandwidth, when compared to a standard antenna, namely, without change. The analysis is also performed at low frequencies, so that the prototype is applicable to UWB (Ultra Wide Band) communication system which occupies the frequency range from 3.1 to 10.6 GHz and another shows a change in bandwidth in center frequency of 2.5 GHz. 2 Design of the Antenna In frequency of THz, for standard antenna, it proposes a microstrip antenna with circular patch of radius r = 24.6 μm, fed by a microstrip line of length b= 21.9 μm and width w = 2.26 μm. The substrate is silicon with relative permittivity (εr) of 11.9 and a thickness of 5 μm. The material used for patch, power line and ground plane is gold. A modification is made making a circular opening of radius R in the center of the ground plane. Figure 1 shows the geometry of the antenna. Mathematical and Computational Methods in Electrical Engineering ISBN: 978-1-61804-329-0 30
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Design of Microstrip Antenna with Greater Bandwidth at Frequencies
of GHz and THz
HUMBERTO CESAR CHAVES FERNANDES, TARCISIO DA SILVA BARRETO AND OTÁVIO