CA1290030C - Multiple resonator component - mountable filter - Google Patents

Abstract

Abstract of the Invention A dielectric block filter which may be mounted on a printed circuit board or other substrate as a single component is disclosed. The dielectric filter utilizes metallized hole foreshortened resonators in the dielectric block, which employs capacitive coupling between resonators controlled in part by an electrode strip coupled to the conductive material covering the majority of the dielectric block surface. Input and output coupling is accomplished via terminals asymmetrically arranged in a mounting bracket. Mounting tabs on the bracket opposite a recessed area holding the dielectric block secure the filter to the circuit board and provide ground connection for the filter. Two or more filters may be arranged on the circuit board to form a duplexer.

Description

i29(303~

~ULTIPL~ RESONATOR COMPONENT - ~OUN~ABLE FILTER

Background of the Invention The present invention is rela~ed generally to radio ~requency (RF) filters, and more particularly to a dielectric band pass ~ilter having an improved capacitive int~r-resonator coupling via metalization and an improved mounting apparatus, producing a filter that i8 particularly well adapted for use in mobile and portable radio transmitting and receiving devices.

Conventional dielectric filters offPr advantages in physical and electrical performance which make them ideally ~uited for use in mobile and portable radio transceivers. Connecting ~he filter input and output termlnals to util~zation means external to the filter, however, has been a problem. Typically, coaxial or other forms of transmission line are ~anually soldered to ~he input and output terminations and then ~ach manually connected to the utilization mean~. When ~uch filters are used as antenna combining duplexers for a transceiver, two dielectric blocks ar~ used and the nu~ber o~ connections doubles. Additionally, the cxitical nature of the connecting transmission line length becomes subject to human error.

~90(:~3~

Summary of the Invention Acaordingly, it is an object of the pre~ent invention to provide a dielectric filter haYing an i~proved capacitive coupling.
It i5 another object o~ the present invention to enable a dielectric filter to have it filter ch~racteristicQ modified by changing metalization coupling the resonators.
It is a further object o~ the present invention to couple improved dielectric filter in a con~iguration which enables their performance as a radio transceiv2r duplexer.
It is a further ob~ect of the present ~nvention to provide a dielectri~ filter interconnection and ~ounting apparatus which enables the dielectric filter to be easily connected to external components.
It is a further object o~ the present invention to enable a dielectric filter to be mounted and connected to a printed circuit board or other substrate elements in a manner similar to other electrical components.
It is a further ob;ect o~ the present invention to couple substrate-mounted dielectric filters in a configur tion which enables their performance as a radio tran~ceiver duplexer.
Therefore, as briefly described, the present invention ~ncompasses a substrate mountable filter comprising a dielectric filter and a moun~ing element.
The dielectric filter has its surfaces substantially covered with a conductive material exc~pt for a first sur~ace. A plurality of holes extend from the first surface t~ a second sur~ace and are 6ubstantially covered by a conductive material which extends from the first urface toward the second eurface. The conductiva material ~f each o~ the holes is disposed with predetermined dis~ances be~ween them. A strip alectrode, ~29~030 3 - ~

~oupled to the conductive material, extends at l~ast partially between two of said holes for ad~usting the capacitive coupling between the holes. Additionally, coupling means, coupled to a separate one of the holes is disposed on the first surface of the dielectric filter.
The mounting element accPpts and holds the dielectric ~ilter in a recessed area, and provides terminal~ for electrical contact to the first and second coupling mean~. The mounting element has tabs opposite the recessed area for mounting o~ a ~ubstrate.

Brief Description_of the Drawin~s Figure 1 is a perspective view of a conventional dielectric ~ilter illustrating th~ orientation of the resonator elements and the input/output coupling.
Figures 2, 3, and 4 are sectional view of Figure 1 illustrating metalization patterns which may be employed in the resonator holes.
Figure 5 is a bot~om perspective of a dielectric block ~ilter and mounting bracket employing th2 present invention.
Figure 6 is a sectional view illustrating an input or output terminal employed in the present invention.
Fi~ure 7 is a dimensional diagram of the mounting bracket employed in the present invention.
Figure 8 is a dimensional view of a printed circuit board mounted duplexer employing component-mountable f~lters.
3~ Figure 9 is a schematic diagram of a component-mountable ~ilter.
Figure 10 is a schematic diagram of the duplexer of Figure 8.
Figure 11 is ~ schematic diagram of a printed circu$t mounted duplexer employing &omponent-mountable filters in a diversity receive antenn configuration.

~.29~t3~

Figure 12A, 12B, 12C, 12D, and 12E illustrate metalization patterns which may be employed in the present invention.
Detailed Description of the Preferred Embodiment In Figure 1, there is illustrated a dielectrically loaded band pass filter 100 employing a conventional input connector 101 and a conv~ntional output connector 103. Such a filter is more fully described in U.S.
Patent No. 4,431,977 "Ceramic Band Pass Filter" and assigned to the assignee of the present invention.
Filter 100 includes a block 105 which is comprised of a dielectric material that is selectively plated with a conductive material. Filter 100 is generally constructed of a suitable dielectric material such as a ceramic material which has low loss, a high dielectric constant, and a low temperature coefficient of the dielectric constant. In the preferred embodiment, filter 100 is comprised of a ceramic compound including barium oxide, titanium oxide and zirconium oxide, the electrical characteristics of which are similar to those described in more detail in an article by G.H. Jonker and W.
Kwestroo, entitled "The Ternary Systems BaO-TiO2-ZrO2", Published in the Journal of the American Ceramic Society, Volume 41, no. 10 at pages 390-394, October, 1958. Of the ceramic compounds described in this article, the compound in table VI having the composition 18.5 mole percent BaO, 77.0 mole percent Tio2 and 4.5 mole percent Zr2 and havin~ a dielectric constant of approximately 40 is well suited for use in the ceramic of the present invention.
A di~lectric filter such as that of block 105 of filter 100 is generally covered or plated, with the exception of areas 107, with an electrically conductive material such as copper or silv~r. A filter such as ~29~33~

block 105 includes a multitude of holes 109 which each extend from the top surface to the bottom ~urface thereo~
and are likewisP plated with an electrically conductive material. The plating o~ the holes 109 is electrically co~mon with the conductiv plating covering th~ block 105 at one end of the holes 109 and isolated from the plating co~ering the block 105 at khe oppo~ite end o~ the holes lO9o Further, the plating of holes 109 at the isolated ~nd may extend onto the top eur~ace of block 105. Thus, each o~ the plated holes 109 i~ essentially a for~shortened coaxial resonator comprised of a short coaxial trans~ission line having a length selected for desired filter response characteristi~s. (Although the block 105 is shown in Fig. 1 with six plat~d holes, any number of plated holes may be utilized dependinq upon the filter response characteristics desired~.
The plating of holes 109 in the filter blo~k 105 is illustrated more clearly by the cross-~ection through any hole 109. Conductive plating 204 on dielectric material 202 extends through hole 201 to the top surface with the exception of a circular portion 240 around hole 201.
Other conductive plating arrangements may also be utilized, two of which are illustrated in Figures 3 and 4. In Fig. 3, conductive plating 304 sn dielectric material 302 extends through hole 301 to the bottom surface with the exception o~ portion 340. The plating arrangement in Fig. 3 is substantially identical to that in Fig. 2, the difference being that unplated portion 340 is on the bottom surface instead of on the top sur~ace.
in Fig. 4, conductive plating 404 on dielectric material 402 extends partially through hole 401 leaving part of hole 401 unplated. The plating arrangement in Fig. 4 can also be reversed as in Fig. 3 so that the unplated portion 440 is on the bottom surface.
Coupling between the plated hole resonators is accomplished through ~he dielectric material and may be 129~)V3~

varied by varying the width of the dielectric material and the di~tance between adjacent coaxial resonators.
The width of the dielectric material between ad~acent holes ~09 can be adjusted in any 6uitable regular or ; irregular manner, ~uch as, ~or example, by the use of ~lots, cylindrical holes, s~uare or rectangular holee, or irregularly shaped hole~.
As shown in Fig. 1, RY s~gnals are capaciti~ely coupled to and ~rom the dielectric ~ilter 100 by means of input and output electrodes 111 and 113, r~6pectively, whlch, in turn, are coupled to input and output conneators 101 and 103, respectively.
The resonant frequency of the coaxial resonators provided by plated holes 109 is deter~ined primarily by the depth of the hole, thickness of the diel~ctric block ~n the direction of the hole, and the amount of plating removed from the top of the filter near the hole. Tuning of ~ilter 100 may be accompli~hed by the removal of additional ground plating or resonator plating extending upon the top surface of the block 105 near the top of each plated hole. The removal o~ plating for tuning the filter can easily be automated, and can be acco~plished by means of a laser, sandblast trimmer, or other suitable trimming device~ while monitoring the return los~ angle of the Pilter.
Re~erring now to Fig. 5, a dielectric filter employing the present invention is shown in a exploded perspective view. A block o~ dielectric material 501 is placed in a carrying bracket 503 which per~ormq the multiple functions of providing a rigid mounting platform ~uch that dielectric block 501 may be inserted into a printed circuit board or other substrate, providing ~implified input and ou~put connections via ~eed through terminals 505 and 507, and providing po~itive ground contact between the conductiYe outer 6urface of : dielec~ric block 501 and bracket 503 via contacts 509, 12~0(~30 510, 511, 512, and other contacts not shown. Contacts 509 and 510 additionally provide a dielectric block 501 locating function within the bracket 503. ~ounting bracket 503 further provides mounting tabs 515-525 to locate and ~upport the bracket and filter on a mounting substratQ and provide positive ground contact for radio frequency signals from the mounting bracket 503 to the receiving mounting substrate. A mounting bracket for a dielectric ~ilter has been disclosed in U.S. Patent ~Jo.
4,742,562 This previously disclosed bracket, however, does not provide the simplified mounting of the bracket of the present inventionO
In one preferred embodiment the dielectric filter 501 consists of a ceramic material and utilizes seven internally plated holes as foreshortened resonators to produce a band pass filter for operation in radio bands reserved for cellular mobile telephone. In this embodiment the conductive plating covering the ceramic block 501 extends conformally on all surfaces except that on which the resonator plating is wrapped from the holes onto the outer surface. Thus, holes 529-535 have corresponding plating 537-543 metalized on the outer surface of block 501. These areas 537-543 are electrically separate from the ground plating but provide capacitive coupling to the ground plating. Additionally, an input plated area 547 and an output plated area 549 provide capacitive coupling between the input terminal 505 and the coaxial resonator formed from the internally plated hole 529 and its externally plated area 537 while plated area 549 provides capacitive coupling between the output terminal 507 and the output resonator formed from plated hole 535 and external plated area 543. Ground 1~90030 stripes 553-558 are plated between the coaxial resonator plated holes in order that inter-resonator coupling i~
adjusted.
Ceramic block 501 is inserted into bracket 503 with the externally plated resonator areas 537-543 oriented downward into the bracket 503 ~uch that addit~onal shielding i~ a~orded by the bracket 503. Input mounting pin 505 is connected to plated ar~a 547 and outpu~
1~ termlnal 507 is connected to plated area 549 as shown in Fig. 6. Input terminal 50~, which may be a low shunt capasity fee~ through such as a lOOB0047 ter~inal manu~actured by ~irpax Electronics Inc., consits of a solderable eyelet 601 and insulating glass bead 603 supporting a center conductor 605. The eyelet 601 is conductively bonded to bracket 503 to provide a secure mounting for the input connector 505. The center conductor 605 is brought into contact with plated area 547 by the dimensions of the bracket 503 and the block 501. The center conductor 605 is soldered or otherwise conductively bonded at one end to area 547 to provide a reliable RF connection to plated area 547. The othPr end ; of the center conductor 605 may then be easily soldered or plugged into a substrate which holds the mounting bracket 503. A similar construction is employed for output terminal 507 and its associated plated area 549.
A detail of the ~ounting bracket 503 is shown in Fig. 7. The spacing of the mounting tabs 515 525 is shown in detail for the preferred embodiment. ThesP
spacings are important a~ the frequencies of operation o~
this filter in order to maintain maximum ultimate attenuation. Low ground path inductance in ths mounting bracket is realized by placing mounting tabs 517 and 519 close to the input and output ports ~505 and 507 of Fig.
5 respectively) and the remainder o~ the tabs above the ~ide and bottom of the bracket 503. Connection between the dielectri¢ block 501 and bracket 503 is assured near ~.Z9~03~

g ~he input and output terminals by contacts similar to contacts 511 and 512 located close to the terminals. All contacts, 509, 510, 511, and 512 (and the equivalent contacts on the opposite side of the brackets not shown), may be ~oldered or otherwise bonded to the dielectric bloak 501 such that electrical connectlon may be permanently assured.
It can be readily ascertained that the position of the tabs 518, 520, and 521 are asymmetrical. Also, the input/output terminal~ 505 and 507 are off~t from the centerline o~ the brarket 503. This asymmetry enables a "keying" of the bracket 503 so that a ~ilter can be inserted in a printed circuit board or other substrate in only one orientation.
one unique aspect o~ the present invention is shown in Fig. 8. A dielectric filter block su~h as block 501 is mounted in bracket 503 and becomes a unitized circuit component which may be inserted into a printed circuit board or substrate 801. Appropriate holes 803 and 805 are located on the printed circuit board 801 to accept the input and ou~put terminals 505 and 507 (not shown in Fig.8), respectively. Further, appropriately located slots ~15-825 are located in the printed circuit board 801 to accept the corresponding tabs of the bracket 503.
Thus the ~ilter 501 and bracke~ 503 may be mounted on a circuit board aO1 lik any other component and circuit runn~r~ may extend from the input hole 803 and the output hole 805 such tha~ the filter may be electrically connected to other circuitry with a minimum of effort.
The circuit board runners, 807 and 809, may be constructed as stripline or microstrip trans~ission lines to yield improved duplexer performance.
: Referring to Fig. 9, there is illustrated an equivalent circuit diagram for the dielectric filter 501 utilized as a band pass filter. An inpu~ signal from a signal ,ourc~ may be applied via terminal 505 to input ~29~33V

ele.ctrode 547 in Fig. 5, whioh corresponds to the common junction of capacitors 924 and 944 in Fig. 9. Capacitor 944 is the capacitance between electrode 547 and the ~urrounding ground plating, and capacitor 924 ls the capacitance between electrode 547 and the coaxial resonator provided by plated hole 529 in Fiy. 5. The coaxial resonators provided by plated 529-535 in Fig. 5 correspond to shorted transmission lines 929-935 in Fig.
9~ Capacitors 937-943 in Fig. 9 represont the capacitance between the coaxial r~eonators provided by the extended plating 537-543 o~ ~he plated holes in Fig.
5 and the ~urrounding ground plating on th~ top sur~ac~.
Capacitor 925 repre~nts the capacitanca between the reaonator provided by plated hole 53S and ~lectrode 549 in Fig. 5, and capacitor 945 represents the capacitance between electrode 549 and the surrounding ground plating.
~n output signal is provided at the junction of capacitors g25 and 945, and coupled to output terminal 547 for utilization by external circuitry.
Referring now to Fig. 10, there is illustra~ed a multi-band filter comprised of two intercoupled dielectric band pass ~ilters 1004 and 1012 and employing the present invention. Two or more of the inventive band pass filters may be intercoupled on a printed cirruit boaxd or subctrate to provide apparatus that combines and/or ~requency sor~s two RF signals into and/or ~rom a composite RF signal. In one application of the preferred embodiment the present invention is employed in the arrangement of Fig. 10 which couples a transmit signal from an RF transmitter 1002 to an antenna 1008 and a receive signal from antenna 1008 to an RF receiver 1014.
The arrangement in Fig. 10 can be advantageously utilized in mobile, portable, and fixed station radios as an antenna duplexer. The transmit signal from RF
~ransmit~er 1002 is coupled ~o filter 1004 by a transmission line 1005, realized by the plated runner 807 ~29()030 of Fig. ~ on the printed circuit board in the preferred embodiment, and the filtered transmit ignal i coupled via circuit bsard runner transmission line 1006 (runner 809 of Fig. ~) to antenna 1008. Filter 1004 is a ceramic band pass filter of the present invention, such as the fllter illustrated in Figs. 5 and 8. The pa~s band of filt~r 1004 is ~entered about the frequency of the transmit ~ignal from RF transmikter 1002, while at the ~ame time greatly attenuating the ~requency of the rscei~ed ~ignal. In addition, the length of transmission line 1006 is select~d to maximize its i~pedance at the frequen~y of the received signal.
A received ~ignal from antenna 1008 in Fig. 10 is coupled by transmission line 1010, also realized as a pxin~ed circuit board runner, to filter 1012 and thence via circuit board runner transmission line 1013 to RF
receiver 1014. Filter 1012, which also may be one of the inventive band pass filters illustrated in Figs. 5 and 8, has a pass band centered about the frequency of the receive signal, while at the ~ame time greatly attenuating the transmit signal. Similarly, the length of transmission line 1010 is selected to maximize its impedanc~ at the transmit ~ignal frequency for further attenuating the transmit signal .
In the embodiment o~ the RF ~ignal duplexing apparatuq of Fig 10, transmit signals having a frequency range from 825 MHz to 851 ~Hz and xeceive signals having a fre~uency range ~rom 870MHz to 896MHz are coupled to the antenna of a mobile radio. The dielectric band pass filterc 1004 and 1012 utilize a dielectric of ceramic and are constructed in accordance with the present invention a~ shown in Fig. 5. The filters 1004 and 1012 each havP
a length of 3.0 inch and a width of 0.45 inch. The 3 5 height is a primary determinant of the frequency of operation and, in the preferred em~odiment, is .49 inch in the transmit filt~r 1004 and 0l44 inch in the receive ~290030 filter 1012. Filter 1004 has an insertion loss of 2.5 dB
and attenuate receive signals by at least 50 dB. Filter 1012 has an insertion loss of 3.0 dB and attenuates receive signals by at least 60 dB. An alternative interconnection of the circuit board mountable dielectric block filters is shown in Fig. 11.
It is sometimes desirable to utilize two swit hable antennas for a receiver so that the antenna receiving the best signal may be switchably coupled to the receiver and provide the well-known antenna diversity function. By not providing a transmission line coupling directly between transmission lines 1006 and 1010 (at point A) but by inserting an antenna switch llO1 selecting a shared transmit/receive antenna 1103 and a receive only antenna 1105 between the antennas, the separate transmit and receive filters 1004 and 1012 may be coupled by 180 reflection coefficient transmission lines 1107 and 1109 in a fashion to provide a diversity receive function.
The filter operational characteristics may be determined by the metalization pattern employed on the surface of the dielectric block which is not fully metalized. Dielectric filters such as described herein are intrinsically coupled by inductance. That is, the magnetic fields in the dielectric material govern the coupling. The inductance may be changed, and even overcome, by introducing capacitance between the resonators. Referring again to Fig. 5, it can be seen that a seven pole configuration is realized by serially coupling the resonators created by the metalized holes 529-535 and surface plating 539-543. As shown, the capacitive coupling b~tween the resonators is restricted by the grounded strip electrodes 554-557. Capacitive coupling by metalization gaps or additional metalization 30~3~
, .
- 12a -islands has been shown in the aforementioned U.S. Patent 4,742,562. According to one novel aspect of the present ~90~30 invention, a controlled capacitive coupling may be achieved by providing incomplete strip alectrodes running on the surface of the dielectric block between two resonatsrs. In the pref2rred embodiment, incomplete strip elactrodes 553 and 558, b~tween input resonator and output re~onator and the other resonators, provide a controlled capacitive coupling to enable combined inductiv~ and capacitive coupling between adjacent resonators. In practice, the use o~ inductiYe or capaci~ive coupling provides ste~per ~ er attenuation skirts on either the high side of the filter passband or the low side of the filter passband, respectively.
When the dielectric filter blocks are csmbined as a duplexer filter as shown diagra~matically in Fig. 10, it is advantageous to employ a filter having a ~tep att~nuation skirt above the passband as the filter pa~sing the lower frequencies. ~l~o it is advantageous to employ a filter having a steep attenuation skirt below the passband as the filter passing the higher frequencies. In this way, additional protection of transmit and receive paths from each other can he realized without additional filter resonator elements.
An advantage of the dielectric filter blocks of the present invention is that the number and spacing of resonators used in the transmitter filter 1004 (of Fig.
10) may be equal to the number and spacing of the resonators in the receive ~ er 1012. The type o~
coupling is determined ~y the metalization pattern employed. The transmit ~ilter 1004 utilizes inductive coupling b~tween resonators as illus~rated in the metalization pattern of Fig. 12A. The capacitive coupling between the middle resonators is reduced by the complete strip electrodes while the input and output resonators utilize more capaci~ance in the incomplete strip electrodes in their coupling to the middle resonators. The receive filter 1012 utilizes capacitive ~29~030 coupling between resonators as illustrated in the metalization pattern of Fig. 12B. Capacitive coupling is enabled by the unblocked metalized resonators.
~Capacitive coupling may be enhanced by metalization islands such as shown in the inductively coupl~d filter of Fig. 12C).
A novel feature of the present invention creates the ability of the coupling to be changed by changing the metalization. Additionally, the mode of resonator operation may be changed from band pass to band stop by utilizing on~ or more resonators as a transmission zero rather than as a transmission pole. Transmission zero realization by metalization change only is shown in Fig.
12D. The output electrode 1203 is coupled to the first transmission pole resonator 1205 by metalization runner 1207. Coupling is also realized from output electrode 1203 to transmission zero resonator 1209. In the embodiment shown, the transmission zero is tuned to the low side of the passband to realize additional rejection on the low side of the passband. A filter utilizing metalization such as that shown in Fig. 12D would be suitable for use in a duplexer such as described above.
Additional zeros may be created by proper coupling to other resonators. Such coupling is shown in the metalization of Fig. 12E.
In summary, then, a printed circuit board mountable, multiple resonator dielectric filter has been shown and described. This filter utilizes metalized hole resonators having coupling characteristics determined by the metalization pattern on one surface of th~ dielectric block. The dielectric block is metalized with a conductive material on all but one surface from which the hole resonators extend into the dielectric block.

12~30 - 14~ -Electrode metalization around the holes provides capacitive coupling to this conductive material and from one resonator to an adjacent resonator. Capacitive coupling between the resonators is controlled by an -~290030 electrode at least partially betwzen two adjacent hole resonators to adjust the capacitive coupling between the resonators. Input and output coupling is accomplished via terminals asymmetrically arranged in a mounting bracket. ~ounting tabs on the bracket opposite a recessed area holding the dielectric block ~ecure the filter to the circuit board and pro~ide ground connection for the filter. Use o~ two ~iltera on a printed circuit board with copper runners forming transmission lines o~ approprlate el~ctrical length creates a duplexer for tran~ceiver applications.
Therefore, while a particular embodiment of the invention has been described and shown, i~ should be understood that the in~ention is not limited thereto since many modifications may be made by those skilled in the art.
It is therefore contemplated to cover any and all such modifications that fall within the true spirit and scope of the basic underlying principles disclosed and claimed herein.

2~

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:

1. A duplexer filter for a radio transceiver employing one antenna for both receiving and transmitting radio signals, comprising:
a first volume of dielectric material having at least two holes extending from a first external surface of a plurality of external surfaces of said first volume toward a second external surface of said plurality of external surfaces of said first volume, all surfaces of said first volume including surfaces within said at least two holes being substantially covered with a conductive material with the exception of said first external surface upon which surface is disposed at least one electrode coupled to said conductive material of one of said at least two hole surfaces;
a second volume of dielectric material having at least two holes extending from a first external surface of a plurality of external surfaces of said second volume toward a second external surface of said plurality of external surfaces of said second volume, all surfaces of said second volume including surfaces within said at least two holes being substantially covered with a conductive material with the exception of said first external surface upon which surface is disposed at least one electrode coupled to said conductive material of one of said at least two hole surfaces;
first mounting means comprising;
(a) a conductive material having a recessed area for accepting and holding said first volume of dielectric material and an interior surface within said recessed area disposed essentially parallel to one of said plurality of external surfaces of said first volume of dielectric material;
(b) a terminal extending through said interior surface and providing electrical contact to said electrode, and (c) a plurality of mounting tabs disposed at predetermined positions opposite said recessed area for affixing said first volume of dielectric material to said substrate for supporting said first volume of dielectric material on a substrate; and coupling means disposed on said substrate for coupling said terminal of said first volume to said second volume whereby receiver signals from the antenna may be rejected by one of said first and second volumes and transmitter signals from the radio transceiver transmitter may be rejected by another of said first and second volumes.

2. A duplexer filter for a radio transceiver employing one antenna for both receiving and transmitting radio signals, comprising:
a first volume of dielectric material having at least two holes extending from a first external surface of a plurality of external surfaces of said first volume toward a second external surface of said plurality of external surfaces of said first volume, all surfaces of said first volume including surfaces within said at least two holes being substantially covered with a conductive material with the exception of said first external surface upon which surface are disposed first and second electrodes coupled to said first and second hole surface conductive materials, respectively, thereby forming resonators which may be tuned to a receiver frequency;

a second volume of dielectric material having at least two holes extending from a first external surface of a plurality of external surfaces of said second volume toward a second external surface of said plurality of external surfaces of said second volume, all/surfaces of said second volume including surfaces within said at least two holes being substantially covered with a conductive material with the exception of said first external surface upon which surface are disposed first and second electrodes coupled to said first and second hole surface conductive materials, respectively, thereby forming resonators which may be tuned to a transmitter frequency;
first mounting means comprising:
(a) a conductive material having a recessed area for accepting and holding said first volume of dielectric material and an interior surface within said recessed area disposed essentially parallel to one of said plurality of external surfaces of said first volume of dielectric material, (b) first and second terminal means extending through said interior surface and providing electrical contact respective to said first and second electrodes, and (c) a plurality of mounting tabs disposed at predetermined positions opposite said recessed area for affixing said first volume of dielectric material to said substrate;
second mounting means comprising:
(a) a conductive material having a recessed area for accepting and holding said second volume of dielectric material and an interior surface within said recessed area disposed essentially parallel to one of said plurality of external surfaces of said second volume of dielectric material, (b) first and second terminal means extending through said interior surface and providing electrical contact respectively to said first and second electrodes, and (c) a plurality of mounting tabs disposed at predetermined positions opposite said recessed area for affixing said second volume of dielectric material to said substrate: and first coupling means disposed on a common substrate for coupling said first electrode of said first volume to said first electrode of said second volume whereby receiver signals from the antenna may be rejected by said second volume and transmitter signals from the transmitter may be rejected by said first volume.

3. A duplexer filter in accordance with claim 2 further comprising:
second coupling means disposed on said substrate for coupling said second terminal of said first mounting means to the radio transceiver receiver; and third coupling means disposed on said substrate for coupling said second terminal of said second mounting means to the radio transceiver transmitter.

4. A duplexer filter for a radio transceiver employing at least one antenna for both receiving and transmitting radio signals, comprising:
a first filter comprising a plurality of resonators formed from at least one hole in a dielectric material being substantially covered with a conductive material and extending from a first external surface of said dielectric material to a second external surface, said dielectric material being substantially covered with a conductive material with the exception of said first external surface upon which surface is disposed at least one electrode coupled to said conductive material of said at least one hole;
a second filter comprising a plurality of resonators formed from at least one hole in dielectric material being substantially covered with a conductive material and extending from a first external surface of said dielectric material to a second external surface, said dielectric material being substantially covered with a conductive material with the exception of said first external surface upon which surface is disposed at least one electrode coupled to said conductive material of said at least one hole;
first mounting means comprising:
(a) a conductive material having a recessed area for accepting and holding said first filter, an interior surface within said recessed area disposed essentially parallel to one of said two external surfaces of said dielectric material of said first filter, (b) a terminal extending through said interior surface and providing electrical contact to said electrode, and (c) a plurality of mounting tabs disposed at predetermined positions opposite said recessed area for affixing said first filter to a substrate; and coupling means disposed on said substrate for coupling said terminal of said first filter to said second filter whereby receiver signals from the at least one antenna may be rejected by one of said first and second filters and transmitter signals from the radio transceiver transmitter may be rejected by another of said first and second filters.

5. A duplexer filter for a radio transceiver employing at least one antenna for both receiving and transmitting radio signals, comprising:
a first filter comprising a plurality of resonators formed from at least one hole in a dielectric material being substantially covered with a conductive material and extending from a first external surface of said dielectric material to a second external surface, said dielectric material being substantially covered with a conductive material with the exception of said first external surface upon which surface is disposed at least one electrode coupled to said conductive material of said at least one hole;
a second filter comprising a plurality of resonators formed from at least one hole in dielectric material being substantially covered with a conductive material and extending from a first external surface of said dielectric material to a second external surface, said dielectric material being substantially covered with a conductive material with the exception of said first external surface upon which surface is disposed at least one electrode coupled to said conductive material of said at least one hole:
first mounting means comprising:
(a) a conductive material having a recessed area for accepting and holding said second filter, an interior surface within said recessed area disposed essentially parallel to one of said two external surfaces of said dielectric material of said first filter, (b) a terminal extending through said interior surface and providing electrical contact to said electrode, and (c) a plurality of mounting tabs disposed at predetermined positions opposite said recessed area for affixing said first filter to a substrate; and coupling means disposed on said substrate for coupling said terminal of said second filter to said first filter whereby transmitter signals from the radio transceiver transmitter may be rejected by one of said first and second filters and receiver signals from the at least one antenna may be rejected by another of said first and second filters.

6. A duplexer filter for a radio transceiver employing at least one antenna for both receiving and transmitting radio signals, comprising:

a first filter comprising a plurality of resonators, at least one of said plurality of resonators formed from a conductive material substantially covering the surface of at least one hole extending from a first external surface of a dielectric material to a second external surface of said dielectric material, said dielectric material being substantially covered with a conductive material with the exception of said first external surface, upon which surface is disposed at least one electrode coupled to said conductive material of said at least one hole;

a second filter comprising a plurality of resonators at least one of said plurality of resonators formed from a conductive material substantially covering the surface of at least one hole extending from a first external surface of a dielectric material to a second external surface of said dielectric material, said dielectric material being substantially covered with a conductive material with the exception of said first external surface, upon which surface is disposed at least one electrode coupled to said conductive material of said at least one hole;
mounting means comprising:

(a) a conductive material having a recessed area for accepting and holding said first filter, an interior surface within said recessed area disposed essentially parallel to one of said two external surfaces of said dielectric material of said first filter, and (b) a terminal extending through said interior surface and coupled to said at least one electrode of said first filter; and coupling means disposed on a substrate for coupling said terminal of said first filter to said second filter whereby receiver signals from the at least one antenna may be rejected by one of said first and second filters and transmitter signals from the radio transceiver transmitter may be rejected by another of said first and second filters.

7. A duplexer filter for a radio transceiver employing at least one antenna for both receiving and transmitting radio signals, comprising:

a first filter comprising a plurality of resonators, at lease one of said plurality of resonators formed from a conductive material substantially covering the surface of at least one hole extending from a first external surface of a dielectric material to a second external surface of said dielectric material, said dielectric material being substantially covered with a conductive material with the exception of said first external surface, upon which surface is disposed at least one electrode coupled to said conductive material of said at least one hole;

a second filter comprising a plurality of resonators, at least one of said plurality of resonators formed from a conductive material substantially covering the surface of at least one hole extending from a first external surface of a dielectric material to a second external surface of said dielectric material, said dielectric material being substantially covered with a conductive material with the exception of said first external surface, upon which surface is disposed at least one electrode coupled to said conductive material of said at least one hole;

mounting means comprising:

(a) A conductive material having a recessed area for accepting and holding said second filter, an interior surface within the said recessed area disposed essentially parallel to one of said two external surfaces of dielectric material of said second filter, and (b) A terminal extending through said interior surface and coupled to said at least one electrode of said second filter; and coupling means disposed on a substrate for coupling said terminal of said second filter to said first filter whereby transmitter signals from the radio transceiver transmitter may be rejected by one of said first and second filters and receiver signals from the at least one antenna may be rejected by another of said first and second filters.