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In this paper, a novel E‐plane waveguide bandpass filter with multiple transmission zeros is proposed in W‐band. The center frequency and bandwidth of this filter can be flexibly designed. Stripe line resonators and L‐shaped resonators are used in the filter. The filter contains four resonators, two of which are used to generate transmission zeros in the upper stopband, and the other two are used to generate transmission zeros in the lower stopband. These transmission zeros can enhance the out‐of‐band suppression and selectivity of the filter. And the position of the transmission zeroes can be flexibly changed as required. One sample is fabricated and measured to verify the proposed filter. The minimum insertion loss in passband is 0.6 dB. Good agreements between the simulated and measured results are achieved. [ABSTRACT FROM AUTHOR]

Photonic bandgap materials have significant applications in the elimination of surface wave on a microstrip antenna. In this paper, several kinds of microstrip structures are analyzed in order to assess their potential for constructing PBG materials. The microstrip structures are periodically loaded with cross dipoles, Jerusalem crosses, or square loops. Periodic Green's functions plus the method of moments (MoM) are introduced to obtain the nonlinear characteristics equation. The real roots are found to show the propagation characteristics of the periodic structure and the existence of bandgap is revealed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 457–458, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10949 [ABSTRACT FROM AUTHOR]