# US 2013/0154772 A1 · Waveguide band-pass filter with pseudo-elliptic response > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154772 A1 - Document ID: US20130154772A1 - Status: Published application - Kind: A1 - Application number: 13/809,109 - Filed: 2010-07-09 - Published: 2013-06-20 - Earliest claimed: 2010-07-09 - Assignees: Politecnico Di Milano - Inventors: Marco Politi - Web page: https://patentgrep.com/patent/US20130154772A1 ## CPC - H01P 1/208: Cascaded cavities; Cascaded resonators inside a hollow waveguide structure (H01P1/205 takes precedence) - H01P 1/207: Hollow waveguide filters (H01P1/212, H01P1/213, H01P1/215, H01P1/219 take precedence) - H01P 1/2016: {Slot line filters; Fin line filters} - H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B) ## Abstract A waveguide band-pass filter is disclosed comprising: an input/output gate for a signal; a first inductive discontinuity coupling device; a second inductive discontinuity coupling device and a first waveguide resonator segment coupled to said input/output gate and interposed between the first and the second coupling devices. At least one of the first and the second coupling devices includes at least a resonant coupling structure which extends in the waveguide with a reduced height relative to a height of the first resonator segment and it is shaped for inputting a zero in a transmission frequency response of the filter. ## Claims ### Claim at position 1 1-15. (canceled) ### Claim 16 A waveguide band-pass filter comprising: an input/output gate for a signal; a first inductive discontinuity coupling device; a second inductive discontinuity coupling device; a first waveguide resonator segment coupled to said input/output gate for a signal and interposed between the first and the second coupling devices; wherein: the first and the second coupling devices include at least a resonant coupling structure which extends in the waveguide with a reduced height in respect to a height of the first resonator waveguide segment and it is shaped for introducing a zero in a transmission frequency response of the filter, and the first and second coupling devices are structured to operate as coupling devices at frequencies of said signal different from a resonance frequency of the at least a resonant coupling structure. ### Claim 17 (depends on 16) The band-pass filter according to claim 16, wherein said at least a resonant coupling structure is such as to resonate at said resonance frequency equal to the frequency value of said zero of the transmission frequency response of the band-pass filter. ### Claim 18 (depends on 17) The band-pass filter according to claim 17, wherein said at least one resonant coupling structure is configured in such a way that to said zero an attenuation peak of the filter is associated in the transmission response. ### Claim 19 (depends on 16) The band-pass filter according to claim 16, wherein said at least one resonant coupling structure comprises at least a reduced-height post. ### Claim 20 (depends on 16) The band-pass filter according to claim 16, wherein: at least one of said first and second coupling devices is an inductive discontinuity device and comprises, preferably, at least a full-height body having a height equal to the first waveguide resonator segment height, or at least one of said first and second coupling devices is an capacitance discontinuity device and comprises, preferably, at least a full-width, reduced-height body in respect to the first waveguide segment height. ### Claim 21 (depends on 16) The band-pass filter according to claim 16, wherein the filter is implemented in one of the following modes: metal waveguide, metal insert waveguide, E-plane type waveguide, dielectric guide with metal coating. ### Claim 22 (depends on 16) The band-pass filter according to claim 16, wherein the filter is implemented in a rectangular waveguide. ### Claim 23 (depends on 16) The band-pass filter according to claim 16, wherein the length of the first resonator waveguide segment is substantially equivalent to the distance between the first and the second coupling devices and it is substantially equal to half of a central wavelength of a pass-band of the filter or multiples thereof. ### Claim 24 (depends on 19) The band-pass filter according to claim 19, wherein said at least one resonant coupling structure extends perpendicularly to a propagation direction of a radiation associated with the signal and parallel to the direction of the electric field of said radiation. ### Claim 25 (depends on 20) The band-pass filter according to claim 20, wherein said full-height body comprises at least one of the following devices: at least a post, at least a symmetrical iris, at least an asymmetrical iris. ### Claim 26 (depends on 22) The band-pass filter according to claim 22, wherein the filter is implemented in a rectangular waveguide and it is sized for propagating and filtering the signal, which propagates according to the electric transverse basic mode and wherein said first input/output gate, the first coupling device, the first resonator segment, the second coupling device are subsequently arranged and aligned along a direction of propagation of said electric transverse basic mode. ### Claim 27 (depends on 16) The band-pass filter according to claim 16, further comprising: a second resonator segment coupled to the second coupling device; and a third discontinuity coupling device connected to said second segment and provided with an output for the radiation. ### Claim 28 (depends on 16) The band-pass filter according to claim 16, further comprising at least a further resonant coupling structure which extends in the reduced-height waveguide in respect to the height of the guide segments and which is configured to introduce a further attenuation zero in the frequency response of the filter. ### Claim 29 (depends on 20) The band-pass filter according to claim 20, wherein said coupling devices are obtained by processing a metal or metallised dielectric lamina secured to shells forming the waveguide. ### Claim 30 (depends on 16) The band-pass filter according to claim 16, wherein the first and the second resonator waveguide segments are such that they resonate at frequencies within the pass-band of the band-pass filter.