Frequency (GHz)

Figure 2 Theoretical model response and numerically simulated performance of the wideband filter

and transmission. The waveguide opening is 7.112 mm in width and 3.556 mm in height. The widths of the consecutive metal inserts are 0.101, 0.255, 0.438, 0.487, 0.438, 0.255, 0.101 mm, and the lengths of the consecutive resonators are 5.844, 6.344, 6.462, 6.462, 6.344, 5.844 mm, respectively. The permittivity of the dielectric material is assumed to be 4.6. It can be seen that the filter already covers a bandwidth of 4 GHz at the lower part of the Ka waveguide band. The simulated results are very close to the expected values calculated directly from the theoretical model. This confirms the applicability of the new structure.

5. CONCLUSION

A new E-plane structure consisting of partial dielectric filling is proposed for the realization of wideband filters. It has been proved that dielectric filling into the metal insert region is an effective technique to increase the parallel impedance in the equivalent circuit, at the same time leaving the serial impedance almost unchanged. This corresponds to an increase of the equivalent ratio of the impedance inverters. The increased ratio results in the capability to realize a wider bandwidth. Because only the first and last metal insert regions are dielectric filled, and the dimensions of these two inserts are the smallest, the additional loss is almost negligible. Furthermore, the structure is fully compatible with the standard waveguide. Thus, no transitions are required. A wideband model bandpass filter covering the 26 30 GHz band in the Ka-band Ž26.5 40 GHz. is designed and analyzed. The theoretical results and the simulated performances are in very good accordance with each other.

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2001 John Wiley & Sons, Inc.

A STUDY ON RESONANCE CHARACTERISTICS OF A MICROSTRIP OPEN-LOOP RESONATOR

Adnan Gorur,¨ ¨ 1 Ceyhun Karpuz,1 Arzu Yilmaz,2

and Kurs¨ ¸at Yalc¸in1

1Department of Electrical and Electronics Engineering Faculty of Engineering and Architecture

Nigde˘ University 51100 Nigde,˘ Turkey

2Turkish Telecommunication Company

51104 Nigde,˘ Turkey

Recei ed 29 May 2001

ABSTRACT: A microstrip open-loop resonator (MOLR) is proposed for maximum miniaturization in microwa e applications, and to obtain a wider upper stopband including the first spurious resonance frequency for planar bandpass filters. The effect of ariation in the width of one of the longer strips of an OLR formed in two ways (namely, fixed-gap (FG) and ariable-gap (VG) OLR) on their resonance characteristics is dis- cussed. Also, simple empirical expressions indicating the effect of aria- tion in the strip width are deri ed for estimation of the resonance frequency as a function of the ariable strip width and the fundamental resonance frequency of the standard loop resonator. 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 177 180, 2001.

Key words: open-loop resonators; slow-wa e structures

1. INTRODUCTION

Miniaturization of components has been a goal of many sectors of the electrical and electronics industries, and the

Contract grant sponsor: Research Fund of University of Nigde,˘ Turkey Contract grant number: FEB.99-008