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Microstrip Filter

IP.com Disclosure Number: IPCOM000084444D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Clouser, PL: AUTHOR

Abstract

Microstrip filter 10 provides a low-loss passband with wide frequency stopbands on each side of the passband.

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Microstrip Filter

Microstrip filter 10 provides a low-loss passband with wide frequency stopbands on each side of the passband.

Filter 10, Fig. 1, has a planar substrate 11 that has a conductive pattern 12 located on one side. Pattern 12 is the signal plane of filter 10. The ground plane, not shown, is located on the opposite side of substrate 11 as a contiguous coextensive conductive layer. Pattern 12 is comprised of a number (e.g., N=nine) of 1/4 wavelength resonators 1 - 9 which are coupled by N-1 through or series.lines designated 1-2, 2-3,... 8-9.

A typical resonator section 20 of a signal conductor pattern is shown in Fig. 2. Each resonator section is designed to be coupled to the series line at a judiciously selected distance X which is sufficiently far from the open end, 20U, so that the desired harmonic to be rejected by the particular section is shorted to ground via the open and shorted shunt sections, e.g., 20U and 20L, respectively, of the particular resonator.

The general equation for determining the parameter X is as follows:

(Image Omitted)

Waveform A, Fig. 3, shows the response characteristic of a typical filter having the present signal plane pattern design. Waveform B shows the response characteristic of a filter having a symmetrically designed signal conductor pattern. It should be noted that the present filter has an improved harmonic rejection in the upper stopband.

The various width dimensions A, B, O and S, Fig. 2, can be derived from the ...