Analytical solution for the design of planar electromagnetic bandgap structures with spurious‐free frequency response

Abstract

In this article, an analytical solution is obtained for the design of electromagnetic bandgap (EBG) structures that feature a single stopband without the spurious rejected bands present in the conventional EBG devices at the harmonics of the design frequency.The proposed technique is applied for the design of microwave filters intended for broadband applications, where closed formulas are found both in two‐port lines and in four‐port coupled lines obtaining very good results. The implementation of the EBG structure in coupled lines allows for the redirection of the reflected signal to the coupled port producing a device with input port matched at all frequencies. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:956–960, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26709

Band-stop filter with suppression of requested number of spurious stopbands

“…Starting from formulas given in [17][18][19], the bandwidth of a stopband measured between its zeros can be expressed as…”

“…Simulations and measurements above 3 f 0 , which are not presented in the paper, show that higherorder stopbands are only partially suppressed. Starting from the coupled mode theory, an analytical solution for periodically nonuniform transmission lines that are free of spurious stopbands is proposed [17][18][19]. The validity of the theory is demonstrated on the example of moderate band BSF with measured results showing full suppression of spurious bandstops at 2 f 0 and 3 f 0 .…”

“…On one hand, the design method represents the generalization of procedures presented in [21,22]. On the other hand, it leans on the theory of periodically nonuniform transmission lines that are free of spurious stopbands [17][18][19]. Construction of unit cell is described in Section II.…”

Passive Microwave Component Design Using Inverse Scattering: Theory and Applications

“…By using Section 3.1, a two-port spurious-free notch-filter can be designed [8], see Figures 1 and 2.…”

“…Fortunately, some modifications on those structures [8] substantially ameliorate their behaviour. Windowing techniques [9] were reported to improve the out-of-band behaviour and chirping techniques [10] were used to enhance the bandwidth performance, while oversized structures were proposed to accomplish very high rejection levels over wide bandwidths [11].…”