WO2014197325A1

WO2014197325A1 - Dielectric waveguide filter with direct coupling and alternative cross-coupling

Info

Publication number: WO2014197325A1
Application number: PCT/US2014/040298
Authority: WO
Inventors: Alexandre Rogozine; Reddy Vangala
Original assignee: Cts Corporation
Priority date: 2013-06-03
Filing date: 2014-05-30
Publication date: 2014-12-11
Also published as: CN105359335A; DE112014002660T5; KR20160013892A; CN105359335B

Abstract

A dielectric waveguide filter which, in one embodiment, is comprised of a plurality of monoblocks coupled together in a side-by-side relationship. In one embodiment, the waveguide filter includes two end monoblocks and two interior monoblocks each defining two resonators. First and second RF signal input/output electrodes are defined on the two end monoblocks. In one embodiment, a direct RF signal transmission path is defined in part by the combination of the resonators, RF signal transmission bridges on each of the monoblocks that interconnect the resonators on each of the monoblocks, and RF signal transmission windows between and interconnecting the resonators of adjacent monoblocks. In one embodiment, alternate or cross-coupling RF signal transmission paths are defined by external RF signal transmission lines that extend between adjacent monoblocks.

Description

DIELECTRIC WAVEGUIDE FILTER

WITH DIRECT COUPLING AND ALTERNATIVE CROSS-COUPLING

Cross-Belemnce

This patent application is a continuation-in-part of ₅ and claims the benefit of the filing date and disclosure of, U.S. Patent App!ication Serial No. 13/373,862 filed on December 3, 2011 and tiled "Dielectric Waveguide Filter with Direct Coupling and Alternative Cross-Coupling" and U, S, Patent Application Serial No. 3/103,712 filed on May 9, 201 1 and titled "Dielectric Waveguide Filter with Structure and Method for Adjusting Bandwidth". This patent application also claims the benefit of the filing date and disclosure of U.S. Provisional Patent Application Serial No. 61/830,476 filed on June 3, 2013. Thes patent

applications are explicitly incorporated herein by referenc as are ail references cited therein.

Field of the Invention

The invention relates generally to dielectric waveguide filters and, more specifically, to a dielectric waveguide filter with direct coupling and alternative cross-coupling.

Back roynd of the invention

This invention is related to a dielectric waveguide filter of the type disclosed in U.S. Patent No. 5,926,079 to Heine et al. in which a plurality of resonators are spaced longitudinally along the length of a monobiock of

dielectric ceramic material and in which a plurality of slots/notches are spaced longitudinally along the length of the monobiock and define a plurality of RF signal bridges of dielectric material between the plurality of resonators which provide a direct inductive/eapacitive coupling between the plurality of resonators.

The attenuation characteristics of a waveguide filter of the type disclosed in U.S. Patent No. 5,926,079 to Heine et al can be increased through the incorporation of zeros in the form of additional resonators located at one or both ends of the waveguide filter. A disadvantage associated with the incorporation of additional resonators, however, is that it also increases the length of the filter which, in some applications, may not be desirable or possible due to, for example, space limitations on a customer's motherboard.

The attenuation characteristics of a filter can also be increased by both direct and cross-coupling of the resonators as disclosed in, for example, U.S. Patent No. 7,714,680 to Vangafa et al. which discloses a rnonoblock filter with both inductive direct coupling and quadruplet cross-coupling of resonators created in part by respective metallization patterns which are defined on the top surface of the filter and extend between selected ones of the resonator through- holes to provide the disclosed direct and cross-coupling of the resonators.

Direct and cross-coupling of the type disclosed in U.S. Patent No.

7,714,680 to VangaJa et al. and comprised of top surface metallization patterns is not applicable in waveguide filters of the type disclosed in U.S. Patent No. 5,926,079 to Heine et al, which includes only slots and no top surface

metallization patterns.

The present invention is thus directed to a dielectric waveguide filter with both direct and optional or alternative cross-coupled resonators which allow for an increase in the attenuation characteristics of the waveguide filter without an increase in the length of the waveguide f ilter.

Summary of the Invention

The present invention is directed to a waveguide fitter comprising a pair of end blocks each defining at least a pair of resonators and an RF signal transmission Input/output transmission electrode, one or more interior RF signal transmission biocks each defining at feast a pair of resonators and located between the pair of end biocks, at least one RF signal transmission bridge defined on each of the end and interior biocks between and interconnecting the pair of resonators, and a plurality of interior RF signal transmission windows defined between each of the end and interior blocks, the combination of the RF signal input output electrodes, the plurality of resonators, the RF signal transmission bridges, and the RF signal transmission windows together defining a direct path for the transmission of an RF signal through the waveguide filter.

In one embodiment, the end and interior blocks comprise separate blocks of dielectric material coupled together in a side-by-side relationship.

In one embodiment, the exterior surface of the end and interior blocks are covered with a layer of conductive material, the plurality of interior RF signal transmission windows being defined by regions of the exterior surface of the end and inferior blocks which are devoid of conductive material.

In one embodiment, the plurality of interior RF signal transmission windows are defined and located between the end and interior blocks.

In one embodiment, an external RF signal transmission line extends between the pair of end blocks and the interior blocks for providing a cross- coupling RF signal transmission path between the interior blocks and the pair of end blocks.

In one embodiment, each of the end and interior blocks defines at least one slit in co-linear relationship with the RF signal transmission bridge.

In one embodiment, the plurality of RF signal transmission window are positioned between the end and interior blocks in an alternating and staggered relationship wherein the RF signal is transmitted through the waveguide filter in a serpentine pattern.

The present invention is also directed to a dielectric waveguide filter comprising a block of dielectric material defining a plurality of resonators arranged in a side-by-side relationship a!ong at least first and second orthogonal axes, first and second RF signal input output electrodes defined on the block of dielectric material, a first direct RF signal path transmission path between the first and second RF signal input output electrodes, the first direct RF signal transmission path extending in the direction of the first and second axes, and a first indirect RF signal transmission path between the first and second RF signal input output electrodes, the first indirect RF signal transmission path extending in the direction of the second axis. in one embodiment, the block of dielectric material defines a plurality of interna? RF signal transmission windows defining at least a portion of the direct RF signal transmission path.

in one embodiment, the plurality of interna! RF signal transmission windows are arranged in an alternating relationship on opposite sides of the longitudinal axis of the waveguide filter to define a generally serpentine-shaped first direct RF signal transmission path,

in one embodiment, an externa! transmission line and the block of dielectric material define the first indirect RF signal transmission path.

In one embodiment, the block of dielectric material is comprised of a plurality of separate blocks of dielectric material coupled together In a side-by- side relationship and the first and second orthogonal axes comprise the x and y axis.

The present invention is further directed to a dielectric waveguide filter comprising first, second, third, and fourth blocks of dielectric material defining first, second, third, and fourth pluralities of resonators, the first, second, third, and fourth blocks of dielectric material being coupled together in an abutting side-by-side relationship, first, second, and third direct coupling RF signal transmission windows defined in the interior of the first, second, third, and fourth blocks of dielectric material for transmitting an RF signal from the first block of dielectric material to the fourth block of dielectric material, and first and second external transmission lines extending respectively between th first and second blocks of dielectric material and the third and fourth blocks of dielectric material for providing an indirect cross-coupling between the first and fourth blocks of dielectric material.

In one embodiment, the first and fourth blocks of dielectric material each define an RF signal input/output electrode, the RF signal transmission windows being arranged in manner for transmitting the RF signal from the first block of dielectric material to the fourth block of dielect ic material i a generally serpentine pattern, in one embodiment, each of the RF signal input output electrodes is defined by a through-hole extending through each of the first and fourth blocks of dielectric material and further comprising first, second, third, and fourth slots in the first, second, third, and fourth blocks of dielectric material aligned in a co- linear relationship to each other and the longitudinal axis of the waveguide filter and separating the respective first, second, third, and fourth pluralities of resonators.

Other advantages and features of th present invention will be more readily apparent from the following detailed description of the embodiments of the invention, the accompanying drawings, and the appended claims.

Brief Description of the Drawings

These and other features of the invention can best be understood b the following description of th accompanying FIGURES as follows:

FIGURE 1 is a perspective view of a dielectric waveguide filter according to the present invention;

FIGURE 2 is a part phantom perspective view of the dielectric waveguide f ilter shown in FIG U RE 1 ;

FIGURE 3 is a part phantom, exploded perspective view of the dielectric waveguide filter shown in FIGURES 1 and 2;

FIGURE 4 is a perspective view of another embodiment of a dielectric waveguide filter according to the present invention;

FIGURE 5 is a part phantom perspective view of the dielectric waveguide filter shown in FIGURE 4;

FIGURE 6 is a part phantom, exploded perspective view of the dielectric waveguide filter shown in FIGURES 4 and 5;

FIGURE 7 is a side elevattonai view of one of the end blocks of the dielectric waveguide filter shown in FIGURES 4 and 5; and

FIGURE 8 is a graph representing the performance/frequenc response of the ceramic dielectric waveguide f ilters depicted in FIGURES 1-7,

S Detaile Description of the Embodiments

FIGURES 1 , 2_» and 3 depict one embodiment of an RF signal waveguide filter 100 in accordance with the present invention which, in the embodiment shown, is an 8-po!e or resonator filter which incorporates both direct RF signal coupling and transmission features and characteristics and alternate cross- coupling/indirect RF signal coupling and transmission features and

characteristics as discussed in more detai! below.

The waveguide filter 100 is, in the embodiment of FIGURES 1 , 2, and 3, made from four separate generally paralle leptped-sha ped monoblocks or blocks 1 1 , 103, 105, and 07 which have been coupled and secured together in a side-by-stde relationship.

Each of the monoblocks or blocks 101 , 103, 105, and 107 is comprised of a suitable dielectric material, such as for example ceramic; defines a longitudinal axis L₅ (FIGURE 1); includes opposed and spaced-apart longitudinal horizontal exterior surfaces 102 extending longitudinally in the same direction as the longitudinal axis L_¾; opposed and spaced-apart longitudinal side vertical exterior surfaces 108 extending longitudinally in the same direction as the longitudinal axis L? and, more specifically, In a relationship on opposed sides of, spaced from, and parallel to, the longitudinal axis L-ii and opposed and spaced-apart transverse side vertical exterior end surfaces 1 10 extending sn a direction generally normal to and Intersecting the longitudinal axis Li ,

In the embodiment shown, a!! of the monoblocks have the same width and height; and the two end monoblocks 101 and 107 are of an equal length greater than the fength of the two interior or intermediate monoblocks 103 and 05 which are of the same length.

The monoblocks 101 , 103, 105, and 107 include respective pluralities of resonant sections (also referred to as cavities or cells or resonators) 1 14 and 1 16; 1 18 and 120; 121 and 122; and 123 and 125 which are spaced and extend longitudinally along the length and longitudinal axis L-$ of the respective monoblocks 101 , 103, 105, and 107 and are separated from each other by a vertical slit or slot 124 (monoblocks 101 and 107) and a vertical silt or slot 126 (monoblocks 103 and 105) that are both cut into the respective monoblocks. An RF signal transmission bridge 128 (on the monobiocks 101 and 107} and an RF signal transmission bridge 130 (on the monoblocks 105 and 107} interconnects the respective resonators as discussed in more detail below.

Each of the slots 124 is cut through one of the longitudinal vertical exterior surfaces 106 and both of the upper and iower horizontal exterior surfaces 1 2 of the respective monoblocks 101 and 107. Each of the slots 124 extends in a relationship normal to and intersecting the longitudinal vertical exterior surface 06 and the longitudinal axis Li and terminates or ends in the body of the respective monoblocks 101 and 1 7 at a point short and spaced from the opposed longitudinal vertical exterior surface 1 6.

Each of the slots 130 is cut through one of the longitudinal vertical exterior surfaces 06 and both of the upper and iower horizontal exterior surfaces 102 of the respective monobiocks 103 and 5, Each of the slots 130 extends in a relationshi normal to and intersecting the longitudinal vertical exterior surface 106 and the longitudinal axis U and terminates or ends in the body of the respective monoblocks 103 and 05 at a point short and spaced from the opposed longitudinal vertical exterior surface 106.

Each of the slots 124 and 126 is co-linear with the respective RF signal transmission bridges 128 and 130 in the monobiocks 101 and 107 and 103 and 105 respectively. Each of the RF signal bridges 28 and 130 interconnect the pair of resonators on each of the respective monoblocks and are each

comprised of a bridge or island of dielectric material which extends in the vertical direction between the top and bottom horizontal surfaces 102 of each of the monoblocks 1 1, 103, 105, and 107 and in the horizontal direction between the respective vertical exterior surface 06 and the end of the respective slots 124 and 1 6, In the embodiment shown, the respective slots 124 and 126 and the respective RF signal bridges 128 and 130 are oriented in a relationship generally norma! to and on opposite sides of the longitudinal axis U of the respective monobiocks 101 , 103, 105, and 107. Specifically, the RF signal transmission bridge 128 o the monobiock 01 bridges and interconnects the dielectric materia! of the resonator 114 to the dielectric material of the resonator 116; the RF signal transmission bridge 130 on the monobiock 103 bridges and interconnects the dielectric materia! of the resonator 118 to the dielectric material of the resonator 1 0; the RF signal transmission bridge 130 on the monobiock 105 bridges and interconnects the dielectric material of the resonator 121 to the dielectric materia! of the resonator 122; and the RF signal transmission bridge 128 on the monobiock 107 bridges and interconnects the dielectric material of the resonator 123 to the dielectric materia! of the resonator 125.

in the embodiment shown, the slots 126 and respective co-linear RF signal bridges 130 are generally centrally located on the respective monobiocks 103 and 105 and the length of each of the slots 124 and 126 Is slightly greater than about half the width of the respectiv monobiocks 101 , 103, 105, and 107 and thus the width of each of the respective co-!inear RF signal transmission bridges 8 and 30 is slightly less than half of the width of each of the

monobiocks 101, 103, 105, and 107.

Depending upon the application and desired performance characteristics, the width, length, and height of the s!ots 124 and 126 may be varied to vary, for example, the width of the respective RF signal bridges 128 and 130,

Th monobiocks 101 and 107 additionally each comprise an electrical RF signal input output electrode i th form of respective through-holes 146 which extend through the body of the respective monobiocks 1 1 and 107 in a direction normal to and co-linear with the longitudinal axis Li thereof and more specifically, through the body of the respective end resonators 114 and 123 defined in the respective monobiocks 101 and 07 and, in a relationship adjacent, spaced from, and parallel to, the transverse vertical end surface 110 of each of the respective monobiocks 101 and 07. In the embodiment shown, each of the monobiocks 101 and 107 includes only one through-hole 146 and defines only one RF signal input output electrode in each of the monobiocks 101 and 07.

Still more specifically, the respective RF signal input output through-holes 146 extend through the body of the respective monoblocks 01 and 107 in a direction and relationship generally normal to the upper and lower longitudinal horizontal exterior surfaces 102 and the iongitudinat axis t₂ and more specifically in a relationship defining respective generally circular openings located and terminating in the upper and tower longitudinal horizontal exterior surfaces 10 of the respective monoblocks 101 and 107,

All of the externa! surfaces 02, 108, and 1 10 of the monoblocks 101, 103, 105, and 107, the interna! surfaces of the respective slots 124 and 126, and the internal surfaces of the input/output through-holes 146 are covered with a suita le conductive material, such as for example silver.

Although not shown in any of the FIGURES, it is understood that S A RF signal input/output oo-axial connectors may be coupled to and extend through the respective through-holes 146 in the monoblocks 101 and 107.

As shown in FIGURES 1 and 2, the separate monoblocks 101 , 103, 105, and 107 are coupled and secured to each other in an abutting side-by-side relationshi as described in more detail below to define and form the waveguide filter 100.

In the embodiment shown, the monoblocks 101 and 103 define the opposed and spaced apart exterior RF signal input output transmission blocks of the waveguide filter 100 while the monoblocks 105 and 107 are sandwiched or located between the two end blocks 101 and 103 and define the two interior RF signal transmission blocks of the waveguide filter 100.

Specifically, and as shown in FIGURES 1 and 2, the monoblocks 101 , 103, 105, and 1 7 are coupled and secured together In an abutting sid by side relationship wherein the longitudinal vertical surfaces 108 of the respective monoblocks 101, 103, 105, and 107 are abutted against each other; the slots 126 on the two interior monoblocks 1 3 and 1 5 are co-lineariy aligned with each other to define and form an internal or interior elongate slot 1 5 defined and located in the center of the waveguide filter 100 in a relationship generally normal to the longitudinal axis Li of the monoblocks 103 and 105 and co-linear with the longitudinal axis L₂ of the waveguide filter 100; and the slots 124 in the respective monoblocks 10 and 107 are disposed in a relationship co-linear with the slots 126 and 135 and with the longitudinal axis U<of the waveguide fitter 100.

Thus, in the relationship as shown in FIGURES 1 and 2, the resonators 1 14, 1 18, 121 , and 123 on the respective monoblocks 101 , 103, 105, and 107 define a first row of resonators disposed in a side-by-side relationship and extending along an x-axis and in the same direction as and on one side of the longitudinal axis L₂ f the waveguide fiiter 100; the resonators 1 6, 120, 1 2, and 125 on the respective monoblocks 101 , 103, 105 and 107 def ine a second row of resonators disposed in a side-by-side relationship and extending along the x-axis and in the same direction as and on the opposite side of the longitudinal axis L₂ of the waveguide filter 100; and the respective pairs of resonators 1 1 and 116, 118 and 120, 121 and 122, and 123 and 128 define respective columns of resonators disposed in a side-by-side relationship and extending along the Y- axis and in a direction transverse to the longitudinal axis Lg. Thus, in the embodiment shown, the blocks 1 1 , 103, 105, and 107, and the respective resonators thereof, are arranged and extend along and in the orthogonal X-Y axis and direction.

The waveguide filter 100 further comprises a first direct coupling RF signal transmission means for transmitting an RF signal directly from the one of the respective RF signal input/output through-holes 146 defining the RF signal input; through the respective resonators 1 14, 1 16, 120, 1 18, 121 , 122, 125, and 123 on the respective monoblocks 101 , 103, 105, and 107; and then through the other of the respective RF signal input/output through-holes 146.

In the embodiment of FIGURES 1 and 2, the direct-coupling RF signal transmission means comprises respective interior or internal RF signal

transmission windows or regions or apertures 622 {FIGURES 2 and 3) defined on respective ones of the longitudinal vertical exterior surfaces 106 of the respective monoblocks 101 , 103, 105, and 107 that are aligned with and abutted against each other when the monoblocks 101 , 103, 105, and 107 are coupled together to define the direct coupling RF signal transmission means and direct path for the transmission of the RF signal from the resonator 118 in the monobiock 101 into the resonator 120 in the monobiock 03: from the resonator 118 in the monobfock 103 into the resonato 121 in the monobiock 105; and from the resonator 122 in the monobfock 105 into the resonator 1 5 in the monobfock 107,

In accordance with the embodiment of the invention as shown in

FIGURES 1 and 2, the interior or Internal RF signal transmission windows 822 comprise generally rectangular-shaped regions on respective ones of the longitudinal vertical exterior surfaces 06 of each of the respective monoblocks 101, 103, 105, and 107 which are devoid of conductive material, i.e., regions of dielectric ceramic material

Thus, and in view of the above description, it is understood that each of the blocks 1 1 _» 103, 105, and 107 includes and defines respective ones of the slots, RF signal transmission bridges, and RF signal transmission windows as described in more detail below.

That is, each of the end RF signal input/output transmission blocks 1 1 and 03 includes one slot 124 extending into the body thereof from one of the longitudinal vertical exterior surfaces 106 thereof; one RF signal transmission bridge 28 co-finear with the one slot 124; one RF signal transmission window 822 located and defined in the other of the longitudinal vertical exterior surface 106 opposite the longitudinal vertical exterior surface 106 with the slot 124 defined therein; and wherein the RF signal transmission window 622 and the RF signal input output through-hole 146 are located at opposite ends of the respective blocks 101 and 103 and on opposite sides of the slot 124 and RF signal transmission bridge 128.

Each of the interior RF signal transmission blocks 1 3 and 105 includes one slot 126 extending into the body thereof from one of the longitudinal vertical exterior surfaces 106 thereof; one RF signal transmission bridge 130 co-linear with the one slot 126; and an RF signal transmission window 622 defined on each of the opposed longitudinal vertical exterior surfaces 106 and located at opposite ends of the respective blocks 103 and 105 and on opposite sides of and spaced from the slot 128 and the RF signal transmission bridge 130.

It is further understood that, In th embodiment of FIGURES 1 , 2, and 3, each of the end blocks 101 and 07 and each of the interior blocks 1 3 and 105 are identical in structure and, more specifically, that in the embodiment of

FIFURES 1 _T 2, and 3_» the block 07 is the block 101 flipped over side to side one hundred eighty degrees and further that the block 105 is the block 103 flipped over side to side hundred eighty degrees.

It is stii! further understood that, in the embodiment of the waveguide filter 100 shown in the FIGURES, the interior or internal RF signal transmission windows 622 are disposed and extend along the longitudinal axis L₂of the waveguide filter 00 in a spaced apart and alternating or staggered relationship on opposite sides of and spaced from the longitudinal axis L₂ of the waveguide filter 100 to define a general serpentine or sine wave shaped direct coupling RF signal transmission path through the waveguide filter 100.

Th waveguide filter 100 additionally comprises first and second indirect, alternative, or cross-coupling RF signal transmission means which, in the embodiment shown, are in the form of external, eross-coupfing indirect coupling, bypass or alternate RF signal transmission electrodes or bridge members or transmission lines 500 and 501 having a specific Impedance and phase and extending between and interconnecting and electrically coupling and

interconnecting the respective resonators 1 14 and 1 8 of the respective monobiocks 101 and 03, and the respective resonators 121 and 123 of the respective monobiocks 105 and 107,

In the embodiment shown, each of the external cross-coupiing

transmission lines 500 and 501 includes and is defined by a generally

recfangufar-shape substrate or printed circuit board which is seated on and bridges the respective top longitudinal horizontal exterior surfaces 102 of the respective monobiocks 101 and 103 and the respective top longitudinal horizontal exterior surfaces 102 of the respective monobiocks 105 and 107. Each of the external cross-coupling transmission electrodes 500 and 501 additional iy includes an elongated strip or line of conductive material 504

(FIGURE 2) defined and formed in the interior of the printed circuit board which bridges and extends over the respective resonators 114 and 118 on the respective monobiocks 01 and 103 and over the respective resonators 121 and 123 on th respective monobiocks 105 and 107 and is adapted for electrical connection to the external layer of conductive material on the exterior surface 102 of the respective monobiocks 101, 103, 106, and 107.

Thus, the assembled or finished waveguide filter 100 as shown in the embodiment of FIGURES 1 and 2 comprises a block of dielectric material defining a central longitudinal axis L₂; a pair of opposed and spaced-apart top and bottom longitudinal horizontal exterior surfaces 102 defined by the top and bottom longitudinal horizontal exterior surfaces 102 of the respective monobiocks 101 , 103, 105, and 107 and extending in the same longitudinal direction as the longitudinal axis L₂; a pair of opposed and spaced-apart longitudinal vertical exterior surfaces 110 defined b the transverse vertical exterior surfaces 110 of the respective monobiocks 101 , 103, 105, and 107 and extending in the same direction as and spaced f om and on opposite sides of the longitudinal axis L₂; and a pair of opposed and spaced-apart transverse vertical exterior end surfaces 106 defined by the longitudinal vertical exterior end surface 106 of the

monoblock 101 and the vertical exterior end surface 1 6 of the monoblock 107 respectively and extending in a direction transverse to and intersecting the longitudinal axis .

The finished waveguide filter 100 still further comprises the pair of RF signal input outputs or electrodes defined in part by the pair of RF signal input/output through-holes 14$ which extend through the body and dielectric material of the block in a relationship and direction generally normal to the longitudinal axis L₂ and terminating in respectiv openings in the top and bottom exterior block surfaces 102 respectively.

In the embodiment of FIGURES 1 and 2, the first of the pair of through- holes 146 is located and defined in a lower corner of the block of dielectric material located below and spaced from the longitudinal axis Lg, while the second of the pair of through-holes 46 is located and defined in a lower diametncaliy opposed comer of the block of dielectric material below and spaced from the longitudinal axis L₂ and co-linear with the first one of the pair of through- holes 146,

The waveguide filter 100 still further comprises and defines the pair of elongate siots 124 defined by the slots 124 formed in the respective monobiocks 101 and 107 and extending from the respective opposed outside transverse vertical surfaces 108 into the body and dielectric material of the biock of dielectric material in a relationship generally co-linear with and intersecting the longitudinal axis L₂ of the waveguide f ilter 100, The slots 124 extend between and through the top and bottom longitudinal horizontal exterior surfaces 02 and respective transverse end surfaces 106 of the waveguide filter 100.

The waveguide filter 100 still further comprises and defines the interior slot 135 defined by the slots 26 in the monobiocks 103 and 05 and extending through the body and dielectric material of the block in a relationship generally co-linear with the longitudinal axis L₂.

The slots 1 4 and 135 defined in the block of the waveguide filter 100 are all positioned in a co-linear and spaced apart relationship relative to each other and in a co-linear relationship relative to the longitudinal axis L2.

In the embodiment of FIGURES 1 and 2, the cross-coupling RF signal transmission lines 500 and 501 are both located below, spaced from, and parallel to the slots 124 and 135 and the longitudinal axis L≥.

In the embodiment of FIGURES 1 and 2, ail of the exterior surfaces 102, 106, and 110; the interior surface of each of the siots 1 4 and 135; and the interior surface of each of the RF signal input/output through-holes 1 8 are covered with a layer of conductive material.

Additionally, in the embodiment of FIGURES 1 and 2, a plurality of interior layers or walls 700 of conductive material extend vertically through the full width and height of the body of the block of the waveguide filter 100 in a spaced apart and parallel relationship relative to each other and in a relationship generally transverse and intersecting the longitudinal axis L₂. Speci ically, a layer or wall 700 of conductive material is located the monobfocks 101 and 03, between the monoblocks 103 and 105, and between the monobiocks 105 and 107. In the embodiment shown, the layer of conductive material on the longitudinal vertical exterior surface 108 of each of the monobiocks 101 , 103, 105, and 107 defines each of the interior layers 700 of conductive material in the waveguide filter 100 when the monobiocks 101, 103, 105, and 107 have been coupled together. in accordance with the Invention, the waveguide filter 100 defines a first magnetic or inductive generally serpentine or sin© wave shaped direct coupling RF signal transmission path for RF signals generally designated by the arrows d in FIGURE 2 successiveiy through the RF signal transmission input through-hole 146; the resonator 1 14 and, more specifically, the resonator 114 in the monobiock 101 ; and into the resonator 1 16 of trie waveguide filter 100 and, more specifically, the resonator 1 16 in the monobiock 101 via and through the RF signal bridge 128 between and interconnecting the resonators 1 4 and 18 and extending in a relationship generally co-linear with the longitudinal axis L₂.

Thereafter, the RF signal is transmitted from the resonator 1 16 into the resonator 120 of the waveguide filter 1 0 and, more specifically, into the resonator 20 of the monobiock 103 via the direct coupling RF signal

transmission means def ined by the interior RF signal transmission window 622 defined in the interior of the waveguide filter 100 between and interconnecting the resonators 1 8 and 120; and then through the resonator 118 in the waveguide filter 100 and, more specifically, through the resonator 118 in the monobiock 103 via and through the RF signal bridge 130 between and interconnecting the resonators 120 and 1 18 and extending in a relationship generally co-linear with the longitudinal axis L₂.

Thereafter, the RF signal is transmitted from the resonator 118 into the resonator 121 of the waveguide f liter 100 via the direct coupling RF signal transmission means defined by the inferior RF signal transmission window 822 defined in the interior of the waveguide filter 100 between the resonators 1 18 and 1 1 and then into the resonator 122 of the waveguide filter 100 and, more specifically, the resonator 122 in the monobiock 103 via and through the RF signal bridge 130 between and interconnecting the resonators 121 and 122 and extending in a relationship generally co-linear with the longitudinal axis L2.

Thereafter, the RF signal is transmitted from the resonator 122 into the resonator 1 5 of the waveguide fiiter 100 and, more specifically, the resonator 125 of the monobiock 107 via the direct coupling RF signal transmission means defined by the interior RF signal transmission window 822 between the resonators 122 and 1 6 and then into the resonator 23 of the waveguide fiiter 100 and, more specifically, the resonator 123 in the monobiock 107 via and through the RF signal bridge 128 between and interconnecting the resonators 125 and 123 and extending in a relationship generally co-linear with the longitudinal axis L₂.

Thereafter, the RF signal passes through the RF signal transmission output through-hole 146 defined in the waveguide fiiter 100 and, more

specifically, defined in the resonator 123 of the monobiock 107,

In accordance with this embodiment of the present invention, the waveguide filter 100 also defines and provides an alternate or indirect* or cross- coupling RF signal transmission paths for RF signals generally designated by the arrows c in FIGURE 2.

One of the cross-coupling or indirect electrical field capacitlve RF signal transmission paths c is defined and created by the external RF signal

transmission line 500 which allows for the transmission of a small portion of the direct RF signai being transmitted through the resonator 1 14 of the waveguide filter 100, and more specifically, the resonator 1 14 of the monobiock 1 1 , to be transmitted directly into the resonator 1 18 of the waveguide fiiter 100, and more specifically the resonator 18 of the monobiock 103, via the interior or internal strip of conductive materia! 504 which bridges and electrically interconnects the respective resonators 1 4 and 1 18 of the waveguide filter 100 and, more specifically, the resonators 1 14 and 1 18 of the respective monoblocks 101 and 103.

The other cross-coupling or indirect magnetic/inductive RF signai transmission path c is defined and created by the other external RF signal transmission line 501 which allows for the transmission of a small portion of the direct RF signal being transmitted through the resonator 121 of the waveguide filter 100 and, more specifically, the resonator 121 of the rnonofolock 105 to be transmitted directly into the resonator 123 of the waveguide filter 100 and, more specifically, the resonator 123 of the monoblock 107,

in accordance with the invention, the cross-coupling of the RF signal as described above advantageously creates respective first and second pairs of transmission zeros, the first pair of which will be located below the passband of the waveguid filter 100 and the second pair of which will be located above the passband of the waveguide filter 100 as shown in FIGURE 8 which is a graph of the performance frequency response of the waveguide filter 100 shown in FIGURES 1 and 2 in which Attenuation (measured in dB) is shown along the vertical or Y axis and Frequency (measured in MHz) is show along the horizontal or X axis.

FIGURES 4, 5, 6, and 7 depict another embodiment of a waveguid filter 200 in accordance with the present invention which is identical in structure and function to the waveguide filter 100 with the exception that the two end

monoblocks 101 and 107 of the waveguide filter 100 have been substituted In the waveguide filter 200 with two end monoblocks 1 a and 107a which are similar in structure and function to the two end monoblocks 101 and 107 except that the two end monoblocks 101a and 107a additionall include respective notches or steps 236 and 238 as described in more detail below. In view of the above, the earlier description of the structure and function of the waveguide filte 100 and the respective monoblocks 101 , 103, 105, and 107 defining the same is incorporated herein by reference with respect to the waveguide filter 200 and the respectiv monoblocks 01a, 103, 105, and 7a defining the same except as otherwise discussed below.

More specifically, the monoblocks 101 a and 107a additionally comprise and define end steps or notches 236 and 238 respectively and each comprising, in the embodiment shown, a generally L-shaped recessed or grooved or shouldered o notched region or section of the lower longitudinal horizontal

1? exterior surface 102, opposed Iongiiucfinal vertical exterior surfaces 06, and end transverse surface 110 of the respective monoblocks 10 a and 1G7a, and more specifically of the respective end resonators 1 14 and 23, from which dielectric ceramic material has been removed or Is absent.

Stated another way, the respective steps 236 and 238 are defined in and by an end section or region of each of the respective monoblocks 01a and 107a, and more specif icaily the respective end resonators 114 and 123, having a height less than the height of the remainder of the respective monoblocks 101a and 107a.

Stated yet another way, and referring to FIGURES 4, 5, 6, and 7, the respective steps 236 and 238 each comprise a generaliy L-shaped recessed or notched portion of the respective end resonators 1 14 and 123 defined on the respective monoblocks 101a and 107a which includes a first generally horizontal exterior surface 240 located or directed inwardly of, spaced from, and parallel to the lower horizontal exterior surf ce 102 of the respective monobtocks 101 a and 103a and a second generally vertical surface or wall 242 located or directed inwardly of, spaced from, and parallel to, the iransverse exterior end surface 1 10 of the respective monoblocks 101 a and 107a,

The monoblocks 101a and 107a additionally each comprise the electrical RF signal input output electrode in the form of the respective through-holes 146 extending through the body of the respective monoblocks 101a and 107a in a relationship generally normal to the longitudinal axis Li thereof and, more specifically, through the respective step 236 and 238 thereof and, still more specifically, through the body of the respective end resonators 1 14 and 123 defined in the respective monoblocks 101 a and 103a between, and in

relationship generaliy normal to, the surface 240 of the respective steps 236 and 238 and the surface 104 of the respective monoblocks 101 a and 103a.

Still more specifically, the respective RF signal input output through-holes 146 are spaced from and generally parallel to the respective transverse side end surface 1 10 of the respective monoblocks 101a and 103a and define respective generally circular openings terminating in the step surface 240 and the top monobiock surface 102 respectively of each of the respective monoblocks 101a and 107a.

The RF signal input output through-holes 146 are located and positioned in and extend through the interior of the respective monobiocks 101a and 107a and the respective steps 236 and 238 between and, in a relationship generally spaced from and parallel to, the side end surface 110 and the step wall or surface 242.

In the embodiment shown, the slot 124 in the respective monoblocks 101a and 107a is located in a relationship spaced, opposed, and generally parallel to, the transverse vertical exterior end surface 1 10 of the respective monoblocks 101a and 107a; the respective through-holes 148 in the respective monoblocks 101a and 107a are located in the respective monoblocks 101a and 107a between the transverse vertical exterior end surface 1 10 of the respective monobiocks 101a and 107a and the slots 124 in the respective monoblocks 101 a and 107a; and the respective steps 236 and 238 and, more specifically, the respective vertical end surfaces 242 thereof, terminate at a point or location short of the respective slots 124, i.e., the respective steps 236 and 238 do not extend into and are spaced from the respective slots 124.

While the invention has been taught with specific reference to the embodiment shown, it is understood that a person of ordinary skill in the art will recognize thai changes can be made in form and detail without departing from the spirit and the scope of the invention, The described embodiment is to be considered in all respects only as illustrative and not restrictive.

For example, it is understood that the waveguide filters 100 and 200 can be modified to includ fewer than 8 poles or greater than 8 poles by removing or adding additional intermediate resonators/monobSocks along the x-axis between the end resonators monoblocks that comprise and include the RF signal input output terminals.

For another example, it is also understood that the waveguide filters 100 and 200 could be modified such that each of the monoblocks comprising the waveguide filter 100 includes and defines additional resonators along the y-axis such as, for example, an embodiment wherein each of the monoblocks defines three resonators separated by two slots and two RF signai transmission bridges.

For another example, it is understood thai the waveguide filters 100 and 200 can be modified to include a plurality of monoblocks with resonators that have been stacked on top of each other along and in an x-z orthogonal axes abutting and side-by-side relationship rather than the x-y orthogonal axes abutting and side~by-side relationship of the embodiment of the FIGURES,

For a further example, and as described in incorporated by reference copending U.S. Patent Application Serial No. 13/373,862, it is understood that the steps 236 and 238 may be of the "step down" or "step in" type disclosed in the FIGURES or of the "step up or "step out" projection type described in

incorporated by reference co-pending U.S. Patent Application Seriai No.

13/373,882, and that the external bandwidth of the waveguide filter can be adjusted either by increasing or decreasing the size (i.e., the depth o thickness) of the "step down" or "step in" steps o by increasing o decreasing the size (i.e., the height) of the "step up" or "step out" step.

Claims

We claim:

1. A waveguide filter comprising:

a pair of end blocks each defining at least a pair of resonators and an RF signal transmission input output transmission electrode;

one or more interior RF signal transmission blocks each defining at least a pair of resonators and located between the pair of end blocks;

at least one RF signal transmission bridge defined on each of the end and interior blocks between and interconnecting the pair of resonators; and

a plurality of interior RF signal transmission windows defined between each of the end and interior bfocks, the combination of the RF signal input output electrodes, the plurality of resonators, the RF signal transmission bridges, and the RF signai transmission windows together defining a direct path for the transmission of an RF signai through the waveguide filter,

2. The waveguide filter of claim 1 wherein the end and interior blocks comprise separate b!ooks of dielectric material coupled together in a side-by-side relationship.

3. The waveguide filter of claim 2 wherein the exterior surface of the end and interior blocks are covered with a layer of conductive material, the plurality of interior RF signal transmission windows being defined by regions of the exterior surface of th end and interior bfocks which are devoid of conductive material.

4. The waveguide filter of claim 3 wherein the plurality of interior RF signai transmission windows are defined and located between the end and interior blocks,

6, The waveguide filter of claim 4 further comprising an external RF signal transmission line extending between th pair of end blocks and the interior biocks for providing a cross-coup! ing RF signal transmission path between the interior biocks and the pair of end blocks,

6. The waveguide filter of claim 5 wherein each of the end and interior biocks define at least one slit in co-linear relationship with the RF signal transmission bridge.

7. The waveguide filter of claim 6 wherein the plurality of RF signal transmission windows are positioned between the end and inferior blocks in an alternating and staggered relationship wherein the RF signa is transmitted through the waveguide filter in a serpentine pattern,

8. A dielectric waveguide filter comprising:

a block of dielectric material defining a plurality of resonators arranged in a side-by-side relationship along at least first and second orthogonal axes;

first and second RF signal input output electrodes defined on the block of dielectric material;

a first direct RF signal path transmission path between the first and second RF signal input output electrodes, the first direct RF signal transmission path extending in the direction of the first and second axes; and

a first indirect RF signal transmission path between the first and second RF signal input output electrodes, the first indirect RF signal transmission path extending in the direction of the second axis.

9« The dielectric waveguide filter of claim 8 wherein the block of dielectric material defines a plurality of internal RF signal transmission windows defining at least a portion of the direct RF signal transmission path.

10, The dielectric waveguide filter of claim 9 wherein the plurality of Internal RF signal transmission windows are arranged in an alternating

relationship on opposite sides of the longitudinal axis of the waveguide filter to define a generally serpentine-shaped first direct RF signal transmission path.

11. The dielectric waveguide filter of claim 0 further comprising an external transmission line and the block of dielectric material defining the first indirect RF signal transmission path, 2. The dielectric waveguide filter of claim 11 wherein the block of dielectric material is comprised of a plurality of separate blocks of dielectric material coupled together in a stde-by-side relationship and the first and second orthogonal axes comprise the x and y axis, 3. A dielectric waveguide filter comprising:

first, second, third, and fourth blocks of dielectric material defining first, second, third, and fourth pluralities of resonators, the first, second, third, and fourth blocks of dielectric material being coupled together in an abutting side-by- side relationship;

first, second, and third direct coupling RF signal transmission windows defined In the interior of the first, second, third, and fourth blocks of dieleciric material for transmitting an RF signal from the first block of dielectric materiai to the fourth block of dielectric material; and

first and second external transmission lines extending respectively between the first and second blocks of dielectric material and the third and fourth blocks of dielectric materiai for providing an indirect cross-coupling between the first and fourth biocks of dielectric material.

14, The dielectric waveguide filter of claim 13 wherein the first and fourth blocks of dielectric material each define an RF signal input/output electrode, the RF signal transmission windows being arranged in a manner fo transmitting the RF signal from the first block of dielectric material to the fourth block of dielectric materia! in a generally serpentine pattern.

15. The dielectric waveguide filter of claim 14 wherein each of the RF signal input output electrodes is defined by a through-hole extending through each of the first and fourth blocks of dieiectric materiai and further comprising first, second, third, and fourth slots in the first, second, third, and fourth blocks of dieiectric material aligned in a co-linear relationship to each other and the longitudinal axis of the waveguide filter and separating the respective first, second, third, and fourth pluralities of resonators.