A Circuit-Modeling Perspective of Leaky-Mode Leakages in a Corner-Fed Square Patch

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概要

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• This paper chronicles the leaky-mode leakages in a corner-fed square patch. First, the measured peak RPA (relative power absorbed, 1 - |S_<11>|^2 - |S_<21>|^2) values of the two-port corner-fed square patch (two-port test circuit) are reported. These are 21.1%, 52.3%, 89.8% and 81.3% at 5.68GHz, 11.76GHz, 16.68GHz and 22.29GHz, respectively. Such periodicity of frequencies and the phenomenon of increasing losses at higher frequencies enable us to link these peak frequencies to leaky-mode excitations. The modal spectra of the higher-order leaky modes with a strip width of 630 mil, equal to the side length of the square patch, are obtained by the well-known space-domain integral equation method. The maximum available power gain (G_<A,max>), obtained by simultaneously complex conjugate matched impedance at the referenced two ports of the test circuit, depicts that (1) nearly loss-free transmission parameter outside the leaky-mode regions and (2) substantial losses inside the leaky-mode regions. This result suggests that the leaky modes are the main sources causing losses for the two-port test circuit. Furthermore, the valley points of the measured and theoretical G_<A,max> are about -7.5dB, -9.7dB and -12.0dB at 10.13GHz, 16.68GHz and 22.29GHz, respectively, and all are in the leaky-mode regions of the modal spectra. The one-port properties of the two-port patch with the second port opened are then investigated. The degenerated (0, N) and (N, 0) modes (N = 1, 2, 3 and 4), calculated by the cavity model method, fall into the strong leakage regions from the first to the fourth higher-order leaky modes. The well-known leaky line's frequency-scanning characteristics also appear in the one-port test circuit, with the angle of the main beam moving from θ = 30°to θ = 40°as the operating frequency is increased from 22.50 GHz to 23.75 GHz. Lastly, a two-dimensional (2-D) transmission-line model of the one-port test circuit is proposed. This model uses two orthogonal modal currents as excitations to stimulate the corner-fed square patch. At 22.60 GHz, in the fourth higher-order leaky mode (EH_4) region, the current distributions obtained by the 2-D transmission-line model closely agree with those of the full-wave simulation. This consistency shows that the damped-oscillation current distributions of the corner-fed square patch at 22.60 GHz are caused significantly by the multiple reflections of the leaky mode. Furthermore, at the resonant frequencies of the patch, the tangled bound-mode resonance of the EH_0 mode can enhance the leaky-mode leakages.

• 社団法人電子情報通信学会の論文
• 2002-08-01

著者

• Chen K‐c

  Institute Of Electrical Communication Engineering National Chiao Tung University

• CHEN Kuo-Cheng

  Institute of Electrical Communication Engineering, National Chiao Tung University

• TZUANG Ching-Kuang

  Institute of Electrical Communication Engineering, National Chiao Tung University

• Tzuang Ching-kuang

  Institute Of Electrical Communication Engineering National Chiao Tung University

関連論文

• A Circuit-Modeling Perspective of Leaky-Mode Leakages in a Corner-Fed Square Patch

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