Quasi-planar leaky-mode antenna employing the second higher order leaky mode of even symmetry in its leaky-wave regime has been proposed for a new antenna configuration consisting of a microstrip and a coplanar waveguide (CPW) on both sides of the substrate. The new antenna, also known as the micro-CPW antenna, is directly fed by a CPW line without matching circuit. One particular -band antenna of 36 mm long [about 2.7 free-space wavelengths ( 0 ) at 22.1 GHz] shows 5.3% impedance bandwidth for VSWR's less than 2.0 for frequencies between 21.927-23.110 GHz, 11.0-dB antenna gain, and 90.02% efficiency. Detailed analyses show that the dual-beam antenna is linearly polarized along two slanted lines, which lie in the longer axes of the ellipses that approximate the radiation contours. Both theoretical and experimental data for the micro-CPW antenna agree very well for the particular design. The proposed micro-CPW antenna is suitable for active integrated antenna integration at higher microwave and millimeter-wave frequencies.Index Terms-Coplanar waveguide, leaky-wave antennas, printed antennas.

A realistic termination scheme is proposed for closely coupled N-conductor microstrips. The design aims to achieve satisfactorily low signal reflection and good fabrication feasibmty for the planar MMIC (Monolithic Microwave Integrated Circuit) process. The matched termination network (MTN) for a lossless three-line coupled microstrip structure is presented. High-speed pulse transmission along terminated tightly coupled microstrip lines is analyzed using modal analysis in the frequency domain. Theoretical results for the propagating and reflected waveforms are obtained by applying the inverse discrete Fourier transform (IDFT) to the system responses. These responses are obtained by applying the theory of multiconductor transmission lines to a dispersive database which has been computed using the spectral-domain approach (SDA). The response of a six-line closely coupled microstrip circuit terminated by the proposed termination scheme is measured using the HPS510B network analyzer. The measured results show that the reflected signal is below-30 dB and the results are in good agreement with the theoretical waveforms.

No abstract

A novel approach of incorporating the bound-mode resonance in a uniform micro-CPW (coplanar waveguide) line that shows excellent input matching is presented. The matrixpencil signal analyses of the CPW-fed micro-CPW guide confirm that two modes, namely, the bound CPW mode and the leaky second higher order microstrip mode, dominate, whereas the microstrip mode contributes too little to be detected. Both theoretical analyses and experimental measurements of the CPW-fed micro-CPW guide show that two well-matched input return losses regions are directly related to the resonances of the CPW mode within the guide.Index Terms-Bound-mode resonance, CPW mode, evensymmetric fields, input return loss, matrix-pencil method, second higher order leaky mode.

This paper presents a novel integrated microstrip low-loss slow-wave line. The new microstrip replaces the conventional metal strip by composite metals paralleling the electric surface and magnetic surface (MS). The MS made of an array of coupled inductors shows a high-impedance state in the stopband, below which the propagation properties can be well controlled by varying the dimensions of the electric surface and MS. The dispersion curves obtained by matrix-pencil analyses closely correspond to those obtained by scattering-parameter extraction. Theoretical results, as confirmed experimentally, indicate that an increase of over 60% in the slow-wave factor can be achieved without sacrificing propagation losses, using the proposed structure. This electric-magnetic-electric (EME) microstrip is insensitive to the alignment position of the periodical structure, and can be constructed using conventional printed-circuit-board fabrication processes and integrated with other microwave components in a multilayered circuit. A compact EME bandpass filter (BPF) with suppressed harmonic responses is presented. The length of the filter is reduced by 26%, and the measured insertion loss and fractional bandwidth is comparable to that of a conventional microstrip BPF on the same substrate.