微带耦合器的中英文对照翻译
Design and Analysis of Wideband Nonuniform Branch Line Coupler and Its Application in a Wideband Butler Matrix
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Yuli K. Ningsih,1,2 M. Asvial,1 and E. T. Rahardjo
Antenna Propagation and Microwave Rearch Group (AMRG), Department of Electrical Engineering, Universitas Indonesia, New Campus UI, West Java, Depok 16424, Indonesia Department of Electrical Engineering, Trisakti University, Kyai Tapa, Grogol, West Jakarta 11440, Indonesia
Received 10 August 2011; Accepted 2 December 2011
Academic Editor: Tayeb A. Denwdny
Copyright ? 2012 Yuli K. Ningsih et al. This is an open access article distributed under the Creative Commons Attribution Licen, which permits unrestricted u, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
法医秦明作者This paper prents a novel wideband nonuniform branch line coupler. An exponential impedance taper is inrted, at the ries arms of the branch line coupler, to enhance the bandwidth. The behavior of the nonuniform coupler was mathematically analyzed, and its design of scattering matrix was derived. For a return loss better than 10?dB, it
achieved 61.1% bandwidth centered at 9GHz. Measured coupling magnitudes and pha exhibit good dispersive characteristic. For the 1dB magnitude difference and pha error within 3°, it achieved 22.2% bandwidth centered at 9GHz. Furthermore, the novel branch line coupler was implemented for a wideband crossover. Crossover was constructed by cascading two wideband nonuniform branch line couplers. The components were employed to design a wideband Butler Matrix working at 9.4GHz. The measurement results show that the reflection coefficient between the output ports is better than 18dB across 8.0GHz–9.6GHz, and the overall pha error is less than 7.
1. Introduction
骑行鞋Recently, a switched-beam antenna system has been widely ud in numerous applications, such as in mobile communication system, satellite system, and modern multifunction radar. This is due to the ability of the switched-beam antenna to decrea the interference and to improve the quality of transmission and also to increa gain and diversity.
The switched-beam system consists of a multibeam switching network and antenna array. The principle of a switched-beam is bad on feeding a signal into an array of antenna with equal power and pha difference. Different structures of multibeam switching networks have been propod, such as the Blass Matrix, the Nolen Matrix, the Rotman
Lens, and the Butler Matrix .
One of the most widely known multibeam switching networks with a linear antenna is the Butler Matrix. Indeed, it ems to be the most attractive option due to its design simplicity and low power loss .
In general, the Butler Matrix is an N × N passive feeding network, compod of branch line coupler, crossover, and pha shifter. The bandwidth of the Butler Matrix is greatly dependent on the performance of the components. However, the Butler Matrix has a narrow bandwidth characteristic due to branch line coupler and crossover has a limited bandwidth. As there is an incread demand to provide high data throughput , it is esntial that the Butler Matrix has to operate over a wide frequency band when ud for angle diversity. Therefore, many papers have reported for the bandwidth enhancement of branch line coupler . In reference , design and realization of branch line c
oupler on multilayer microstrip structure was reported. The designs can achieve a wideband characteristic. However, the disadvantages of the designs are large in dimension and bulk.
Reference introduces a compact coupler in an N-ction
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tandem-connected structure. The design resulted in a wide bandwidth. Another design, two elliptically shaped microstrip lines which are broadside coupled through an elliptically shaped slot, was employed in . This design was ud in a UWB coupler with high return loss and
isolation. However, the designs require a more complex manufacturing.
In this paper, nonuniform branch line coupler using exponential impedance taper is propod which can enhance bandwidth and can be implemented for Butler Matrix, as shown in Figure
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1. Moreover, it is a simple design without needs of using multilayer technology. This will lead in cost reduction and in design simplification.
Figure 1:Geometry structure of a new nonuniform branch line coupler design with exponential impedance taper at the ries arm.
淡淡的忧伤鲢鱼怎么钓To design the new branch line coupler, firstly, the ries arm’s impedance is modified. The shunt arm remains unchanged. Reduced of the width of the transmission line at this arm is desired by modifying the ries arm. Next, by exponential impedance taper at the ries arm, a good match over a high frequency can be achieved.
2. Mathematical Analysis of Nonuniform Branch Line Coupler
The propod nonuniform branch line coupler u λ/4 branches with impedance of 50Ω at the shunt arms and u the exponential impedance taper at the ries arms, as shown in Figure
1. Since branch line coupler has a symmetric structure, the
even-odd mode theory can be employed to analyze the nonuniform characteristics. The four ports can be simplified to a two-port problem in which the even and odd mode signals are fed to two collinear inputs [22].
Figure 2 shows the schematic of circuit the nonuniform branch line coupiers.
Figure 2:Circuit of the nonuniform branch line coupler.
The circuit of Figure 2 can be decompod into the superposition of an even-mode excitation and an odd-mode excitation is shown in Figures and .
Figure 3:Decomposition of the nonuniform branch line coupler into even and odd modes of excitation.
The ABCD matrices of each mode can be expresd following . In the ca of nonuniform branch line coupler, the matrices for the even and odd modes become:
A branch line coupler has been designed bad on the theory of small reflection, by the continuously tapered line with exponential tapers , as indicated in Figure 1, where
which determines the constant as:
Uful conversions for two-port network parameters for the even and odd modes of S11 and S21 can be defined as follows :
where
法经Since the amplitude of the incident waves for the two ports are ±1/2, the amplitudes of the emerging wave at each port of the nonuniform branch line coupler can be expresd as
Parameters even and odd modes of S11 nonuniform branch line
