Ceramic bandpass filter

Claim 2

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 3

The filter according to claim 1, wherein the dielectric means is comprised of a block of a dielectric material having the shape of parallelepiped.

Claim 4

The filter according to claim 1, further including between said holes at least one additional hole for adjusting the electrical signal coupling from the first electrode means to the second electrode means.

Claim 5

The filter according to claim 1, or 2, further including a signal source for generating an input signal with respect to signal ground, the input signal being coupled to one of the first and second electrode means, and the conductive material covering the dielectric means being coupled to signal ground.

Claim 6

A filter comprising: means comprised of a dielectric material having parallel, flat, top and bottom surface, said dielectric means having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material plated on the top surface of the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material plated on the top surface of the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being plated entirely with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 7

A filter comprising: means comprised of a dielectric material having parallel, flat, top and bottom surface, said dielectric means having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material plated on the top surface of the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material plated on the top surface of the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being plated entirely with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 8

The filter according to claim 5, wherein the dielectric means is comprised of a block of a dielectric material having the shape of parallelepiped.

Claim 9

The filter according to claim 5, further including between said holes at least one additional hole for adjusting the electrical signal coupling from the first electrode means to the second electrode means.

Claim 10

The filter according to claim 5, or 6, further including a signal source for generating an input signal with respect to signal ground, the input signal being coupled to one of the first and second electrode means, and the conductive material covering the dielectric means being coupled to signal ground.

Claim 11

A filter comprising: means comprised of a dielectric material having a top surface, a bottom surface and first and second side surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed on one of the first and second side surfaces of the dielectric means at a predetermined distance from the top surface and substantially opposite one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on one of the first and second side surfaces of the dielectric means at a predetermined distance from the top surface and substantially opposite a hole other than said one of the holes in the dielectric means; and said dielectric means further being entirely covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 12

A filter comprising: means comprised of a dielectric material having a top surface, a bottom surface and first and second side surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed on one of the first and second side surfaces of the dielectric means at a predetermined distance from the top surface and substantially opposite one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on one of the first and second side surfaces of the dielectric means at a predetermined distance from the top surface and substantially opposite a hole other than said one of the holes in the dielectric means; and said dielectric means further being entirely covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 13

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least three holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another, each of said holes having a predetermined amount of electrical coupling to each other hole; first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being entirely covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 14

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least three holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another, each of said holes having a predetermined amount of electrical coupling to each other hole; first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being entirely covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 15

A multi-band filter comprising: (a) first filtering means comprising: (i) means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; (ii) first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; (iii) second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and (iv) said dielectric means further being covered entirely with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole; and (b) second filtering means comprising: (i) means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; (ii) first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; (iii) second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and (iv) said dielectric means further being covered entirely with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole; and (c) means for coupling the first electrode means of the first filtering means to the first electrode means of the second filtering means.

Claim 16

A multi-band filter comprising: (a) first filtering means comprising: (i) means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; (ii) first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; (iii) second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and (iv) said dielectric means further being covered entirely with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole; and (b) second filtering means comprising: (i) means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; (ii) first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; (iii) second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and (iv) said dielectric means further being covered entirely with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole; and (c) means for coupling the first electrode means of the first filtering means to the first electrode means of the second filtering means.

Claim 17

The multi-band filter according to claim 11, further including radio frequency (RF) transmitting means for generating a transmit signal, RF receiving means adapted to receive a receive signal, and means for radiating an RF signal; the transmit signal being coupled to the second electrode means of the first filtering means, the receive signal being coupled to the second electrode means of the second filtering means, and the radiating means being coupled to the first electrode means of the first filtering means and the first electrode means of the second filtering means.

Claim 18

The multi-band filter according to claim 12, further including first transmission line means interposed between the first electrode means of the first filtering means and the radiating means, said first transmission line means having a length such that its impedance is a maximum at the frequency of the receive signal; and further including second transmission line means interposed between the first electrode means of the second filtering means and the radiating means, said second transmission line means having a length such that its impedance is a maximum at the frequency of the transmit signal.

Claim 19

The multi-band filter according to claim 11, further including first radio frequency (RF) transmitting means for generating a first transmit signal, second RF transmitting means for generating a second transmit signal, and means for radiating an RF signal; the first transmit signal being coupled to the second electrode means of the first filtering means, the second transmit signal being coupled to the second electrode means of the second filtering means, and the radiating means being coupled to the first electrode means of the first filtering means and the first electrode means of the second bandpass filtering means.

Claim 20

The multi-band filter according to claim 14, further including first transmission line means interposed between the first electrode means of the first filtering means and the radiating means, said first transmission line means having a length such that its impedance is a maximum at the frequency of the receive signal; and further including second transmission line means interposed between the first electrode means of the second filtering means and the radiating mans, said second transmission line means having a length such that its impedance is a maximum at the frequency of the transmit signal.

Claim 21

The multi-band filter according to claim 11, further including first radio frequency (RF) receiving means adapted to receive a first receive signal, second RF receiving means adapted to receive a second receive signal, and means for radiating an RF signal; the first receive signal being coupled to the second electrode means of the first filtering means, the second receive signal being coupled to the second electrode means of the second filtering means, and the radiating means being coupled to the first electrode means of the first filtering means and the first electrode means of the second filtering means.

Claim 22

The multi-band filter according to claim 16, further including first transmission line means interposed between the first electrode means of the first filtering means and the radiating means, said first transmission line means having a length such that its impedance is a maximum at the frequency of the receive signal; and further including second transmission line means interposed between the first electrode means of the second filtering means and the radiating means, said second transmission line means having a length such that its impedance is a maximum at the frequency of the transmit signal.

Claim 23

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole, and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 24

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole, and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 25

The filter according to claim 18, wherein the dielectric means is comprised of a block of a dielectric material having the shape of parallelpiped.

Claim 26

The filter according to claim 18, further including between said holes at least one additional hole for adjusting the electrical signal coupling from the first electrode means to the second electrode means.

Claim 27

The filter according to claim 18, further including a signal source for generating an input signal with respect to signal ground, the input signal being coupled to one of the first and second electrode means, and the conductive material covering the dielectric means being coupled to signal ground.

Claim 28

A filter comprising: means comprised of a dielectric material having first and second surfaces, said dielectric means further having at least two holes extending from the first surface toward the second surface thereof and spatially disposed at a predetermined distance from one another; first coupling means associated with one of the holes in the dielectric means; second coupling means associated with a hole other than said one of the holes in the dielectric means; and said dielectric means further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole, and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 29

A filter comprising: means comprised of a dielectric material having first and second surfaces, said dielectric means further having at least two holes extending from the first surface toward the second surface thereof and spatially disposed at a predetermined distance from one another; first coupling means associated with one of the holes in the dielectric means; second coupling means associated with a hole other than said one of the holes in the dielectric means; and said dielectric means further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole, and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 30

The filter according to claim 22, wherein the dielectric means is comprised of a block of dielectric material having the shape of parallelpiped.

Claim 31

The filter according to claim 22, further including between said holes at least one additional hole for adjusting the electrical signal coupling from the first coupling means to the second coupling means.

Claim 32

The filter according to claim 22, further including a signal source for generating an input signal with respect to signal ground, the input signal being coupled to one of the first and second coupling means, and the conductive material covering the dielectric means being coupled to signal ground.

Claim 33

A filter comprising: a block comprised of a dielectric material having first and second surfaces, said dielectric block further having at least two holes extending from the first surface toward the second surface thereof and spatially disposed at a predetermined distance from one another; a first electrode associated with one of the holes in the dielectric block; a second electrode associated with a hole other than said one of the holes in the dielectric block; and said dielectric block further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole, and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 34

A filter comprising: a block comprised of a dielectric material having first and second surfaces, said dielectric block further having at least two holes extending from the first surface toward the second surface thereof and spatially disposed at a predetermined distance from one another; a first electrode associated with one of the holes in the dielectric block; a second electrode associated with a hole other than said one of the holes in the dielectric block; and said dielectric block further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole, and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 35

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further including at least one slot between said one hole and said other hole for adjusting the electrical signal coupling from the first electrode means to the second electrode means, and said dielectric means further being covered with a conductive material with the exception of portions near the slot, near one end of said one hole and said other hole and near the first and second electrode means.

Claim 36

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further including at least one slot between said one hole and said other hole for adjusting the electrical signal coupling from the first electrode means to the second electrode means, and said dielectric means further being covered with a conductive material with the exception of portions near the slot, near one end of said one hole and said other hole and near the first and second electrode means.

Claim 37

The filter according to claim 27, wherein said slots are covered with a conductive material.

Claim 38

The filter according to claim 27, wherein said dielectric means has two end surfaces and two side surfaces, and said slots are disposed on at least one of the top, bottom and side surfaces.

Claim 39

The filter according to claim 29, wherein said slots are disposed on at least two opposite surfaces.

Claim 40

A filter comprising: means comprised of a dielectric material having parallel, flat, top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material plated on the top surface of the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material plated on the top surface of the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further including at least one slot between said one hole and said other hole for adjusting the electrical signal coupling from the first electrode means to the second electrode means, and said dielectric means further being plated with a conductive material with the exception of portions near the slot, near one end of said one hole and said other hole and near the first and second electrode means.

Claim 41

A filter comprising: means comprised of a dielectric material having parallel, flat, top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material plated on the top surface of the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material plated on the top surface of the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further including at least one slot between said one hole and said other hole for adjusting the electrical signal coupling from the first electrode means to the second electrode means, and said dielectric means further being plated with a conductive material with the exception of portions near the slot, near one end of said one hole and said other hole and near the first and second electrode means.

Claim 42

The filter according to claim 31, wherein said slots are plated with a conductive material.

Claim 43

The filter according to claim 31, wherein said dielectric means has two end surfaces and two side surfaces, and said slots are disposed on at least one of the top, bottom and side surfaces.

Claim 44

The filter according to claim 33, wherein said slots are disposed on at least two opposite surfaces.

Claim 45

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further including at least one slot between said one hole and said other hole for adjusting the electrical signal from the first electrode means to the second electrode means, and said dielectric means further being covered with a conductive material with the exception of portions near the slot and near one end of said one hole and said outer hole.

Claim 46

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further including at least one slot between said one hole and said other hole for adjusting the electrical signal from the first electrode means to the second electrode means, and said dielectric means further being covered with a conductive material with the exception of portions near the slot and near one end of said one hole and said outer hole.

Claim 47

The filter according to claim 35, wherein said slots are covered with a conductive material.

Claim 48

The filter according to claim 35, wherein said dielectric means has two end surfaces and two side surfaces, and said slots are disposed on at least one of the top, bottom and side surfaces.

Claim 49

The filter according to claim 39, wherein said slots are disposed on at least two opposite surfaces.

Claim 50

A filter comprising: means comprised of a dielectric material having first and second surfaces, said dielectric means further having at least two holes extending from the first surface toward the second surface thereof and spatially disposed at a predetermined distance from one another; first coupling means associated with one of the holes in the dielectric means; second coupling means associated with a hole other than said one of the holes in the dielectric means; and said dielectric means further including at least one slot between said one hole and said other hole for adjusting the electrical signal coupling from the first coupling means to the second coupling means, and said dielectric means further being entirely covered with a conductive material with the exception of portions near the slot and near one end of said one hole and said other hole.

Claim 51

A filter comprising: means comprised of a dielectric material having first and second surfaces, said dielectric means further having at least two holes extending from the first surface toward the second surface thereof and spatially disposed at a predetermined distance from one another; first coupling means associated with one of the holes in the dielectric means; second coupling means associated with a hole other than said one of the holes in the dielectric means; and said dielectric means further including at least one slot between said one hole and said other hole for adjusting the electrical signal coupling from the first coupling means to the second coupling means, and said dielectric means further being entirely covered with a conductive material with the exception of portions near the slot and near one end of said one hole and said other hole.

Claim 52

The filter according to claim 39, wherein said slots are covered with a conductive material.

Claim 53

The filter according to claim 39, wherein said dielectric means has two end surfaces and two side surfaces, and said slots are disposed on at least one of the top, bottom and side surfaces.

Claim 54

The filter according to claim 41, wherein said slots are disposed on at least two opposite surfaces.

Claim 61

The method according to claim 45, wherein said step (c) includes the step of producing at least one slot in the dielectric means between said one hole and said other hole.

Claim 62

The method according to claim 45, wherein said step (c) includes the step of producing at least one additional hole in the dielectric means between said one hole and said other hole.

Claim 63

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being overlapped on the surface of the dielectric means and capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.

Claim 64

A filter comprising: means comprised of a dielectric material having top and bottom surfaces, said dielectric means further having at least two holes extending from the top surface toward the bottom surface thereof and spatially disposed at a predetermined distance from one another; first electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from one of the holes in the dielectric means; second electrode means comprised of a conductive material disposed on the dielectric means at a predetermined distance from a hole other than said one of the holes in the dielectric means; and said dielectric means further being covered with a conductive material with the exception of portions surrounding one end of said one hole and said other hole and surrounding the first and second electrode means, and the conductive material at said one end of each hole further being overlapped on the surface of the dielectric means and capacitively coupled to the surrounding conductive material whereby a foreshortened coaxial resonator is produced for each hole.