Microwave bandpass filter with higher harmonics rejection function

Claim 2

A rectangular waveguide filter having a passband for transmittinG electromagnetic waves including a fundamental frequency and attenuating a second harmonic or said fundamental frequency in a fundamental mode TE101 keeping resonant frequencies of modes higher than said mode TE101 outside of the region where the second harmonic of said fundamental frequency exists comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said rods and said waveguide forming a resonator cavity; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective means for enabling said cavity to provide said filter passband to transmit said fundamental frequency band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said mode TE101 from coming into a frequency region including said second harmonic; and adjustable capacitive means disposed in at least one of said wide walls and adjusted to project one end into the interior of said cavity to function as a capacitive means only for said fundamental mode thereby providing said filter cavity passband; said last-mentioned means having an axis disposed in a position which is located between planes including corresponding axes of said respective susceptance means at one-half of said one-third waveguide wavelength therebetween and which is further located from an inner surface of at least one of said narrow walls proximate to said capacitive means at one-third of an overall distance between inner surfaces of said narrow walls.

Claim 3

The waveguide filter according to claim 1 in which said capacitive means comprises two adjustable screws having some spaced in mutually parallel relation in said one wide wall in a plane perpendicular to said narrow and wide walls, each screw adjusted to project one end into said cavity; said two screw axes spaced in two positions which include said first-mentioned position and are located said one-half of said one-third waveguide wavelength distance between said two planes including said corresponding axes of said susceptance means and which include each of said two screw axes further located said one-third distance from said inner surface of an adjacent narrow wall and said two screw axes having said one-third distance therebetween.

Claim 4

The waveguide filter according to claim 1 in which said capacitive means comprises an adjustable screw disposed in said one wide wall to project one end into said cavity and having an axis in said position which is located said one-half of said one-third waveguide wavelength distance between said two planes including said two susceptance means corresponding axes and which is further located said one-third distance from said inner surface of said adjacent one narrow wall.

Claim 5

The waveguide filter according to claim 1 in which said capacitive means comprises two adjustable screws of which one is disposed in said one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project respective one ends thereof into said cavity and having axes in said position which is located said one-half of said one-third waveguide wavelength distance between said two planes including said susceptance means corresponding axes and which is further located said one-third distance from inner surfaces of said respective narrow walls.

Claim 6

The waveguide filter according to claim 1 in which said capacitive means comprises two adjustable screws having axes spaced in mutually parallel relation in said one wide wall in a plane perpendicular to said wide walls and parallel to said narrow walls; said two screws adjusted to project coRresponding ends into said cavity and to dispose opposing peripheral portions approximately at said position which is located said one-half of said one-third waveguide wavelength distance between said two planes including said susceptance means corresponding axes and which is further located said one-third distance from said inner surface of said adjacent one narrow wall.

Claim 7

The waveguide filter according to claim 1 in which said filter means comprises two adjustable screws of which one is disposed in said one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project respective one ends into said cavity and having axes in said position which is located said one-half of said one-third waveguide wavelength distance between said two planes including said two susceptance means corresponding axes and which is further located said one-third distance from said inner surface of said one narrow wall.

Claim 8

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE101, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for providing said passband to transmit said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said mode from coming into a frequency region including said second harmonic; and two adjustable screws having lengthwise axes spaced in mutually parallel relation in one wide wall in a first plane perpendicular to said narrow and wide walls; said two screws adjusted to project corresponding ends into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said first plane equidistantly located between two other planes including said lengthwise axes of said rods of said respective susceptance means at a distance of one-half of said one-third waveguide wavelength distance; said screw lengthwise axes further located from inner surfaces of respective adjacent narrow walls at one-third of an overall distance between said last-mentioned surfaces and said screw lengthwise axes having said one-third distance therebetween in said first plane.

Claim 9

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE101, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for providing said passband to transmit said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said mode from coming into a frequency region including said second harmonic; and two adjustable screws having lengthwise axes spaced in mutually parallel relation in one wide wall in a first plane perpendicular to said narrow and wide walls; said two screws adjusted to project corresponding ends into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said first plane equidistantly located between two other planes including said lengthwise axes of said rods of said respective susceptance means at a distance of one-half of said one-third waveguide wavelength distance; said screw lengthwise axes further located from inner surfaces of respective adjacent narrow walls at one-third of an overall distance between said last-mentioned surfaces and said screw lengthwise axes having said one-third distance therebetween in said first plane.

Claim 10

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE101, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency rEgion including said second harmonic; and an adjustable screw disposed in one wide wall and adjusted to project one end into said cavity to function as a capacity only for said fundamental mode to provide said filter passbands; said screw having a lengthwise axis equidistantly located between two planes including lengthwise axes of said rods of said respective susceptance means at a distance of one-half of said one-third waveguide wavelength distance; said screw lengthwise axis further located from an inner surface of an adjacent narrow wall at one-third of an overall distance between inner surfaces of said narrow walls.

Claim 11

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE101, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency rEgion including said second harmonic; and an adjustable screw disposed in one wide wall and adjusted to project one end into said cavity to function as a capacity only for said fundamental mode to provide said filter passbands; said screw having a lengthwise axis equidistantly located between two planes including lengthwise axes of said rods of said respective susceptance means at a distance of one-half of said one-third waveguide wavelength distance; said screw lengthwise axis further located from an inner surface of an adjacent narrow wall at one-third of an overall distance between inner surfaces of said narrow walls.

Claim 12

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE101, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective two means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and two adjustable screws of which one is disposed in one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project respective one ends thereof into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said two screws having lengthwise axes equidistantly located between two planes including lengthwise axes of said rods of said respective two means at a distance of one-half of said one-third waveguide wavelength distance; said one and second screw lengthwise axes further located from inner surfaces of said respective adjacent narrow walls at one-third of an overall distance between said last-mentioned inner surfaces.

Claim 13

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE101, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and said rods forming a resonator cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective two means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and two adjustable screws of which one is disposed in one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project respective one ends thereof into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said two screws having lengthwise axes equidistantly located between two planes including lengthwise axes of said rods of said respective two means at a distance of one-half of said one-third waveguide wavelength distance; said one and second screw lengthwise axes further located from inner surfaces of said respective adjacent narrow walls at one-third of an overall distance between said last-mentioned inner surfaces.

Claim 14

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE101, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and rods forming a resonator cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective two means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and two adjustable screws spaced in mutually parallel relation in one wide wall and adjusted to project respective one ends thereof into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said two screws having lengthwise axes disposed in parallel in a plane perpendicular to said wide walls and parallel to said narrow walls and also having opposing peripheral portions located approximately at a distance equidistantly between two planes including lengthwise axes of said rods of said respective susceptance means at one-half of said one-third waveguide wavelength distance; said two screws having said lengthwise axes thereof located from an inner surface of an adjacent narrow wall at one-third of an overall distance between said narrow walls.

Claim 15

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency in a fundamental mode TE101, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and rods forming a resonator cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective two means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and two adjustable screws spaced in mutually parallel relation in one wide wall and adjusted to project respective one ends thereof into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said two screws having lengthwise axes disposed in parallel in a plane perpendicular to said wide walls and parallel to said narrow walls and also having opposing peripheral portions located approximately at a distance equidistantly between two planes including lengthwise axes of said rods of said respective susceptance means at one-half of said one-third waveguide wavelength distance; said two screws having said lengthwise axes thereof located from an inner surface of an adjacent narrow wall at one-third of an overall distance between said narrow walls.

Claim 16

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and rods forming a resonating cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective two means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and two adjustable screws of which one is disposed in one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project corresponding respective opposite ends into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said two screws having lengthwise axes equidistantly located between two planes including lengthwise axes of said rods in said respective two means at a distance of one-half of said one-third waveguide wavelength distance; said two screw lengthwise axes further located from an inner surface of one narrow wall at one-third of an overall distance between said narrow walls.

Claim 17

A rectangular waveguide filter having a passband for transmitting a band of electromagnetic waves including a fundamental frequency and attenuating at least a second harmonic of said fundamental frequency, comprising: a rectangular waveguide having narrow and wide opposite walls; two susceptance means spaced in mutually parallel relation interiorly of said waveguide in a direction lengthwise of said wide walls and disposed transversely to said narrow walls; each of said means consisting of a plurality of rods spaced in mutually parallel relation in a further direction perpendicular to said transverse direction; said waveguide and rods forming a resonating cavity for transmitting said waves; said two means so spaced as to provide a distance of one-third waveguide wavelength between lengthwise axes of corresponding rods in said respective two means for enabling said cavity to transmit said fundamental band and to attenuate said second harmonic while preventing resonant frequencies of modes higher than said fundamental mode from coming into a frequency region including said second harmonic; and two adjustable screws of which one is disposed in one wide wall and a second in the opposite wide wall; said one and second screws adjusted to project corresponding respective opposite ends into said cavity to function as capacities only for said fundamental mode to provide said filter passband; said two screws having lengthwise axes equidistantly located between two planes including lengthwise axes of said rods in said respective two means at a distance of one-half of said one-third waveguide wavelength distance; said two screw lengthwise axes further located from an inner surface of one narrow wall at one-third of an overall distance between said narrow walls.