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A modification of the conventional dumbbell-shaped coplanar waveguide defected ground structure (DGS) is proposed. This modification permits the continuous tuning of the rejected frequencies by using reconfiguration technique and it allows the control of the DGS equivalent-circuit model. The modified DGS possesses two-dimensional symmetry, hence, it has been studied under different symmetry conditions and the corresponding equivalent-circuit model in each case has been developed. Based upon this study, a tunable bandstop DGS resonator is proposed. 19% tuning range centered at 3.7 and 7.4 GHz, respectively, is achieved. The equivalent-circuit model of the resonator is also developed. All proposed structures have been fabricated. Measurements as well as three-dimensional simulations are found to be in a very good agreement with theoretical predictions. Index Terms--Coplanar waveguide (CPW), defected ground structure (DGS), tunable bandstop resonator.

This letter introduces a simple technique to reduce cross polarization in multilayer antipodal linearly tapered slot antenna taking advantage of the slab air-filled substrate integrated waveguide (SAFSIW) topology. The operation mechanism is presented together with simulations and experimental validations. The measured results show a reflection coefficient lower than –17 dB over the Ka-band. A measured gain of 13 ± 1.35 dBi is observed in the overall Ka-band. The proposed broadband structure achieves a measured cross-polarization isolation of better than 16.07 dB at endfire direction over the Ka-band, which is a significant improvement compared to its multilayer AFSIW implementation counterpart. [ABSTRACT FROM AUTHOR]

This article introduces two-way broadband air-filled substrate integrated waveguide (AFSIW) isolated power dividers/combiners based on surface mounted absorbing materials. The proposed structures take advantage of the AFSIW multilayer feature. The absorber implementation is found highly tolerant of variations in dimensions and positioning. Three different power dividers/combiners topologies are analyzed theoretically, simulatively, and experimentally. The measurement results validate the broadband responses of the fabricated Ka-band demonstrators. The proposed power dividers/combiners are intended to exploit high-power AFSIW system on substrate (up to few hundred watts). [ABSTRACT FROM AUTHOR]

This letter introduces stepped-impedance bandpass filters based on the slab air-filled substrate integrated waveguide (SAFSIW), which provides a compromise in terms of loss and footprint between substrate integrated waveguide (SIW) and air-filled SIW (AFSIW). First, the theoretical unloaded quality factor of the SAFSIW guided-wave structure is presented. Then, a design procedure of SAFSIW stepped-impedance bandpass filters is introduced. Finally, for demonstration purposes, a third-order Chebyshev filter, centered at 30 GHz, is synthesized, optimized, fabricated, and measured. With a low-cost FR-4 to enclose the structure, a return loss better than 15 dB with a minimum insertion loss of 0.99 dB in the passband is obtained in experiments. [ABSTRACT FROM AUTHOR]

In this paper, coplanar waveguide filters with etched-ground stubs that have multiple behaviors are proposed. The response of a unit cell is a bandreject with one or more transmission zeros according to the number and the lengths of the stubs. A library of transmission line models is being built for the basic cells and then used for the design of more elaborated structures. The potential of these new topologies is highlighted by providing different filtering structures with interesting features: a second-order narrow bandpass filter, and two configurations for a lowpass filter with a wide stopband. All theoretical predictions have been verified by electromagnetic simulation and measurements. [ABSTRACT FROM AUTHOR]

This article presents an improved factor of merit for the comparison of center-frequency tunable bandpass filters. This study draws up a comparison between existing tunable filters for which different commonly used parameters demonstrating their performance are given. A first factor of merit that takes all the major characteristics of such tunable filters into account is introduced. A second factor of merit is proposed to evaluate the filter compactness. These new factors of merit are applied for the comparison of more than 30 recently published papers. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 985–988, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24220 [ABSTRACT FROM AUTHOR]

A compact topology for bandpass filters based on coupled slow-wave resonators is demonstrated. A study of fixed band-pass filters leads to design rules and equations. Measurements on a 0.7-GHz fixed bandpass filter, consisting of three coupled slow-wave resonators, demonstrate the validity of the proposed topology and validate the theory, since the agreement between simulations and measurements is very good. Designed for a Q-factor of 5, this filter shows a Q of approximately 5.2. At the center frequency, insertion loss is 0.6 dB and return loss is greater than 20 dB. A 0.7-GHz tune-all bandpass filter is also designed and tested. The performance of this electronically tuned filter, which incorporates semiconductor varactors, is promising in terms of wide continuous center-frequency and bandwidth tunings. For a center-frequency tuning of ±18% around 0.7 GHz, the -3-dB bandwidth can be simultaneously tuned between ∼50 and ∼78 MHz, with an insertion loss smaller than 5 dB and a return loss greater than 13 dB at the center frequency. The surface areas of the fixed and tunable 0.7-GHz filters are, respectively, ∼16 and ∼20 cm². [ABSTRACT FROM AUTHOR]

Different simulation methods for analyzing microwave interconnects are presented. Dynamic and static as well as two-dimensional (2D) or three-dimensional (3D) methods are investigated, such as the method of moments (MoM) the SDM, and TLM method, in their specific domains of predilection. Results are finally compared together with those obtained from a commercial software product based can the FEM method. [ABSTRACT FROM AUTHOR]

A microwave integrated, tunable, low-pass filter is presented. This coplanar filter exhibits a wide tuning range of the cutoff frequency (±19% around 4.3 GHz) and a -30 dB stopband that extends up to 30 GHz. Insertion loss is 1.5 dB at low frequencies and return loss is better than 14 dB in the passband. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2566–2568, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23707 [ABSTRACT FROM AUTHOR]

We describe an optically controlled microwave attenuator based on a microstrip reverse directional coupler where optical illumination modifies the loads at the coupling and transmission ports. A tunable attenuation up to 10 dB was measured at the center frequency, Experimental and theoretical results are compared and agree well. [ABSTRACT FROM AUTHOR]