US 2001/0054943 A1 · Distributed element filter

Abstract

A band pass distributed element filter having real and imaginary transmission zeros by sequentially connecting half wavelength microstrip resonators and adding a cross coupling circuit has been difficult to implement as a planar circuit on the same plane, since the cross coupling circuit crosses one of the resonators. The distributed element filter is constructed by sequentially connecting n half wavelength microstrip resonators (n is an even number equal to or more than 4) each formed from a straight or hairpin microstrip line, wherein the number of straight microstrip lines and the number of hairpin microstrip lines are both odd, and wherein quarter wavelength straight microstrip lines for external circuit connection are coupled to the first and n.th resonators, respectively, and a cross coupling circuit is connected to the microstrip lines of these resonators or to the ends coupled to the microstrip lines. A band pass filter can thus be realized using only a planar circuit by preventing the cross coupling circuit from crossing any one of the resonators.

Claims10

Dependent claims

A distributed element filter comprising:

n half wavelength of a passband center frequency, microstrip resonators consisting of straight and hairpin microstrip lines wherein n is an even number equal to or more than 4, the n half wavelength microstrip resonators being connected sequentially with each resonator coupled with adjacent resonators over a length of approximately one quarter wavelength, respective numbers of straight microstrip lines and hairpin microstrip lines of the n half wavelength microstrip resonators being both odd;
an external circuit connection quarter wavelength straight microstrip lines coupled to first and n-th half wavelength microstrip resonators, respectively;
and
a cross coupling circuit connected to ends of the first and n-th half microstrip resonators, the ends being of a side on which the first and n-th half microstrip resonators are coupled with the external circuit connecting quarter wavelength straight microstrip lines, or to ends of the external circuit connection quarter wavelength straight microstrip lines.

1 more element

A distributed element filter comprising:

n half wavelength corresponding to a passband center frequency, microstrip resonators consisting of straight and hairpin microstrip lines wherein n is an even number equal to or more than 4, the n half wavelength microstrip resonators being connected sequentially with each resonator coupled with adjacent resonators over a length of approximately one quarter wavelength, respective numbers of straight microstrip lines and hairpin microstrip lines of the n half wavelength microstrip resonators being both odd;
an external circuit connection quarter wavelength straight microstrip lines coupled to first and n-th half wavelength microstrip resonators, respectively;
and
a cross coupling circuit consisting of an a/2 wavelength microstrip line and a b/2 wavelength microstrip line capacitively coupled via a slit (a and b are natural numbers), the cross coupling circuit being connected to ends of the first and n-th half microstrip resonators, the ends being of a side on which the first and n-th half microstrip resonators are coupled with the external circuit connection quarter wavelength straight microstrip lines, or to ends of the external circuit connection quarter wavelength straight microstrip lines.

1 more element

Dependencies are inferred from the claim text.

Distributed element filter

Life of this patent

Distributed element filter

Life of this patent

Abstract

Claims10