CA1133119A - Nondissipative load termination for traveling wave array antenna - Google Patents
Nondissipative load termination for traveling wave array antennaInfo
- Publication number
- CA1133119A CA1133119A CA348,990A CA348990A CA1133119A CA 1133119 A CA1133119 A CA 1133119A CA 348990 A CA348990 A CA 348990A CA 1133119 A CA1133119 A CA 1133119A
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- Canada
- Prior art keywords
- waveguide
- radiating
- load termination
- traveling wave
- array
- Prior art date
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- Expired
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- 230000010287 polarization Effects 0.000 claims abstract description 6
- 230000001131 transforming effect Effects 0.000 claims description 8
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 238000003491 array Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
- H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/0006—Particular feeding systems
- H01Q21/0037—Particular feeding systems linear waveguide fed arrays
- H01Q21/0043—Slotted waveguides
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- Waveguide Aerials (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
Abstract
ABSTRACT
This specification discloses a nondissipative load termination for a traveling wave antenna array whereby energy incident at the end of the antenna array is applied directly to the main beam of the array with the same polarization as the main beam so that the gain of the antenna is improved.
This specification discloses a nondissipative load termination for a traveling wave antenna array whereby energy incident at the end of the antenna array is applied directly to the main beam of the array with the same polarization as the main beam so that the gain of the antenna is improved.
Description
~3~
~ 1 --BAC~GROUND OF THE INVENTION
1) Field of the Invention This invention relates to antennas and, more particularly, to traveling wave antennas.
~ 1 --BAC~GROUND OF THE INVENTION
1) Field of the Invention This invention relates to antennas and, more particularly, to traveling wave antennas.
2) Prior Art The load termina~ion for a traveling wavy array should absorb or radiate without reflecting all the energy incident upon the end of the array to avoid a large back lobe~ Known prior art traveling wave arrays have utilized two kinds of load terminations: resistive and radiating. An internal nonradiating resistive termination absorbs all of the ener~y, typically about 10% of the total energy incident upon the end of the array, so that no refIected back lobe in the antenna pattern occurs. When a resistive termination is used, the efficiency of the array cannot exceed 90~ because of the energy lost in the resistive loadO Further, resistors for such terminations typically dissipate several to tens of watts or more power, and they require considerable space and care in mounting ~o~ thermal control.
On ~he other hand, prior art radiating load te~minations dissipate all energy incident upon the end of the array in a dIrection :or polarization other than the principal polarization and direction of the main beam of ~he array. Thus, prior art radiating load terminations do not contribute to the gain and efficiency of the traveling wave array. Radiating loads have been used on the back sides of traveling wave arrays. The radiation takes place on the inside of the cylinder into which the array is mounted and is wasted. These are some of the
On ~he other hand, prior art radiating load te~minations dissipate all energy incident upon the end of the array in a dIrection :or polarization other than the principal polarization and direction of the main beam of ~he array. Thus, prior art radiating load terminations do not contribute to the gain and efficiency of the traveling wave array. Radiating loads have been used on the back sides of traveling wave arrays. The radiation takes place on the inside of the cylinder into which the array is mounted and is wasted. These are some of the
3~ problems this invention overcomes.
, ' ~
5~MMARY OF l'HE INVENTION
. This invention teaches a radiating load terminatio~ which applies energy incident at the end of a traveling wave array directly into the main beam of the ~rray with the same polarization as ~he main beam so that ~he gain of the ante~na is improve~. The nondissipative radiating load permits the efficiency to approach 100% by radiating ra~her than absorbing the energy incident upon the end of the array. An apparatus in accordance wi~h an embodiment of this invention does not interfere with typical design procedures used for minimizing the side lobe level of the traveling wa~e array. This radiating load also increases efficiency, reduces manufacturing cost, reduces construction complexity and weight, and contributes to th gain of ~he array.
A particul rly advantageous use is for terminat-ing traveling wave array antennas mounted in groups on ~mall cylinders to orm tracking or search beams on an active radar guided miss~le application. The elimination ' of the resistiYe load termination results in a compact 2n design which permits packaging several antennas onto a mall missile and avoids the cost of hand labor and ~aterials associated with the res;istive load termination.
In accordance with an embodiment o~ this inven-. tion, an antenna includes an apertured wave guide having a nondissipative lDad termination means for radiatirg en~rgyin a direction substantially parallel to the wave guide~
In a first embodime~t, the nondissipative load termination means includes an open end wave guide radiating load adjacent to a slot means for impedance transforming a section of ~he wave guide adjacent nonresonant slots of the traveli~g wa~e array.
More particularly, there is provided:
An antenna with a main beam comprising:
an apertured waveguide traveling wave array including a plurality of waveguide slots and a radiating load termination means for radiating electromagnetic energy in a direction parallel with said waveguide, said radiating load termination means being a radiating load termination for applying electromagnetic energy incident at the ~ " , ~33~
-2a-end of the antenna directly to the main beam of the antenna with the same polarization as the main beam so that gain of the antenna is improved, said apertured waveguide traveling wave array directly exciting said radiating load termination means so that substantially all input power into said traveling wave array is available for beam formation, and said radiating load termination being nondissipative so that substantially no electromagnetic energy is converted to heat, said radiating load termination including a quarter wave transormer having transformer 510t means for impedance transforming in a section of said waveguide adjacent said waveguide slots of said traveling wave array, said waveguide slots being nonresonant and shorter in length than said transformer means.
There is also provided:
An antenna with a main beam comprising:
an apertured waveguide traveling wave array including a plurality of waveguide ~lots and a radiating load termination means for radiating electromagnetic energy in a direction parallel with said waveguide, said xadiating load termination means being a radiating load termination for applying electro-magnetic energy at the end of the antenna directly to the main beam so that gain of the antenna is improved, said apertured waveguide traveling wave array directly exciting said radiating load termination means so that substantially all input power into said traveling wave array is available for beam forma~ion and said radiating load termination being nondissipative so that substantially no electromagnetic energy is converted to heat, ~L~33~ ~ ~
-2b-said radiating load termination including a broad wall slot means for terminating said traveling waveguide array, and a waveguide impedance matching section means adjacent said broad wall slot for providing a closed end to said waveguide and terminating a residual amount of energy, said nondissipative load termination means having a residual reflection coe~ficient 50 that there is reflected energy whose magnitude is the same and whose phase is opposite to that of a back lobe of the antenna :~`
thus cancelling the back lobe, said broad wall slot means being longer in length than said waveguide slots.
_RIEF DESCRIPTION OF THE D~AWI~
~ ig. 1 is a perspective view of an end portion o~ a txaveling wave array ~ntenna config~red in accordance wi~h a first embodimenl: of ~his invention having an open end wa~eguide radiating load;. ;~
.
.
.. . . .
:
;~33 3 ~
Fig~ 2 is a perspective ~iew of an end portion of a traveling wave~antenna array in accordance ~ith a second embodiment of this invention having a b~oad wall slot with radiating load adjacent a closed ~nd of a traveling waveguide antenna;
~ ig. 3 is a top plan view of the ~mbodiment of Fig. 2; and FigO 4 is a side elevation view of the embodiment of Fig. 2 including a coaxial tuning stub in accordance with an embodiment of this invention.
DETAILED DESCR~PTION OF THE INVENTION
Figs. 1 and 2-each show one type of nondissipative radiating load and impedance transformer sections used with a dielectric filled waveguide traveling wave array of transverse nonresonant slots in th~ broadwall of the waveguide~ The ~onfiguration shown in Fig. 1 is particularly useul for long ~raveling wave arrays, for example those ha~ing a length greater than ten times the wavelength of the signal being - radiated. The configuration shown in FigO 2 is particularly ; 20 useful for short traveling wave arrays, for example those :having a length less than ~i~e times the wavelength.
Referring first to Fig. 1, a traveling wa~e array 12 is terminated in an open end waveguide radiating load 20 preceded by three slots 21 which serve as an impedence transforming section 22 betweén radiating load 20 and the final nonresonant slots 23 of traveling wa~e array 12.
Slots 21 and 23 are closely spaced at about 0.1 wavelength or less. Slots 21 alter the ~haracteristic impedence and ~elocity of propagation of transforming section 22 and are longer t~an the slots 23 in the traveling wave array 12.
Slots 21 span appro~imately a quarter guide wavelength.
The altered waveguide characteristic impedance in impedance transformer section 22 is somewhat higher than that of the -array 12 due to the shorter array slots 23 and less than the impedance of the open end waveguide radiating load 20 ~333L:~ ~
at the end of traveling wave array 12. Thus, the waveguide section with the longer 510ts 21 (impedance transformer ~ection 22) serves as a quarter wave transformer between - ~he traveling ~ave array 12 and the radiating load 20.
To minimize the array backlo~e of traveling wave array 12, relative to an unterminated array, the transformed impedance of the radiating load should not exactly match ~he characteristic impedance of traveling wave array 12.
The transformed impedance should provide a small negative re~lection coefficient which will give rise to a small reilection lobe to cancel the backlobe of the radiating load. The need for an imperfect impedance match becomes greater as the array directivity decreases.
In a second type of -radiating load shown in Fig~ 2, a single broad wall slot 32 terminates a txaveling wave array 13 and is followed by a shorted waveguide impedance matching section 33. Such an arrangement is particularly suited to low directivity arrays which requixe an imperfect impedance match with a negative reflection coefficient (i.e., one wherein the phase is reversed) to minimize the array back-lobe. The length o radiating load slot 32 and shorted waveguide length both can be adj~sted to yield a wide range of negative reflection coefficient values to mlnimize the backlobe of traveling wave array 13 for a wide range of array directivity values~ In an electrical equivalent model the reactance of the shorted waveguide section would be in series with the impedance of the radiating load slot.
~ he traveling wave array 12 shown in Fig. 1 has ~een applied to end fire traveling wave array consisting of closely spaced, nonresonant transverse slots in a dielectric loaded waveguide. The measured gain of the array cperating at X-band was lS. 5 dB with the radiating load and 15. 2dB when a resistive load termination was used~ The 0.3 dB gain improvement represents a 0.6 dB improvement in system performance in two way active radar applications. The measured back lobe of the array relative to peak gain was -20 dB with the radiating load and -30 dB with a resistive load termination. The array was approximately 16 inches long ~13~
~ 5 ~
by 1/2 inch wide by 1/16 inch ~hick and was fabricated according to known printed circuit techniques. The absence of a resistive load termination permitted the installation.
of eight antennas on a 3-1~2 inch diameter cylinder without drilling holes into the structure at the load end of each ~ntennaJ
The traveling wave array 13 shown in Fig. 2 has been applied to a near end fire array ~beam centered 23 from end fire) of a similar design as that referred to in the previous paragraph but having lower gain than the previously dis~ussed end fire array~ The m asured gai~ of the near end fire array was 13 dB with the second type radiating load. The gain improvement attributable to the radiating loa~ was determined to be 0~ 4 dB~ The measured 1~ back lobe relative to the peak gain of the array was 15 dB.
~ he nondissipative radiating load described above radiates in a manner which contributes to forward gain, permits optimization of the back lobe level relative to an unterminated array and it does not interfere with the normal design procedure or minimizing the side lobe level of the traveling wa~e array.
Referring to Figs. 3 and 4. a traveling wave array 13a includes a coaxial tuning stub 40 which is positioned about 0.43 inches from the end of array 13a and about 0.05 25 inches off the longi~udinal axis of array 13aO The furthest edge of the radiating load slot 32a is about 0.67 inches from the end of axray 13a, and the furtherest edge of the closest of slots 31a is about 0.77 inches from end array 13a. The length of a slot 31a is about 0~292 inches, the length of slot 32a is about 0~43 inchesO The length of slots 31a goes down to about 0.22 inches at the left end of array 13a. In contrast, the total width of array 13a increases from a right width of about 0.455 inches to a left width of a~out 0.513 inches. The left coaxial input terminal 35 41 is positioned about 0.116 inches off center and about - 0.49 inches from tne left end array 13. The thickness of array 13 is about 0.062 inches. ~he to~al length of array ~33~ ~ ~
~ ~ o 13a is about 5~12 inches and the length containing slots 31a along array 13a is 3.7 inches.
The shor~ circuited waveguide serves as a reactive tUning element which primarily affects only the last slot in a manner which causes this slot to radiate all of the remaining energy which was not radiated by the traveling wave array and to suppress the s~anding wave which would otherwise .. .. .. . . . .
occur within the waveguide. In practice, the radiating load termi~ation produces a small residual reflection coefficient 10 whose magnitude is the same and whose phase is opposite to that of the back lobe. Thus r the reflection coef ficient cancels the baok lobe. In other words, the amount of energy which is reflected due to the reflection coefficient is egual to the normal back lobe of the traveling wave axray, I5 thus allowing the enersy of the radiating load to be added to the main beam.
With respect to Fig. 1, an open end waveguiae radiating load is preceded by ~hree slots which serve as an impedance transforming section terminating the final non-20 resonant slots of the traveling wave array. The slots alterthe characteristic impedance and velocity of propagation of the waveguide. The waveguide characteristic impedance in the transforming section will be somewhat higher than that o the shorter array slots and less than ~he impedance of ~he 2~ open end waveguide radiating load. Thus, the waveguide section with ~he longer slots serves as a quarter wav~ trans-former between the traveling wave array and the radiating load. As is well known in the art~ a ~uarter wave trans~
former can couple any impedance with another impedance. In 30 Fig. 2, the radiating load consists of a single broad wall slo~ terminating the traveling wave array, followed by a shorted waveguide impedance matching sectionO
Various modifications and variations will no doubt occur to those s~illed in the various arts to which this ~5 invention pertains. For example, the particular radiating loads transformer sections and traveling wave arrays may be varied from those described herein~ These and all other o 7 variations which basically rely on the teachings through which this disclosure has advanced the art are properly considered within the scope of this invention.
o ..
, ' ~
5~MMARY OF l'HE INVENTION
. This invention teaches a radiating load terminatio~ which applies energy incident at the end of a traveling wave array directly into the main beam of the ~rray with the same polarization as ~he main beam so that ~he gain of the ante~na is improve~. The nondissipative radiating load permits the efficiency to approach 100% by radiating ra~her than absorbing the energy incident upon the end of the array. An apparatus in accordance wi~h an embodiment of this invention does not interfere with typical design procedures used for minimizing the side lobe level of the traveling wa~e array. This radiating load also increases efficiency, reduces manufacturing cost, reduces construction complexity and weight, and contributes to th gain of ~he array.
A particul rly advantageous use is for terminat-ing traveling wave array antennas mounted in groups on ~mall cylinders to orm tracking or search beams on an active radar guided miss~le application. The elimination ' of the resistiYe load termination results in a compact 2n design which permits packaging several antennas onto a mall missile and avoids the cost of hand labor and ~aterials associated with the res;istive load termination.
In accordance with an embodiment o~ this inven-. tion, an antenna includes an apertured wave guide having a nondissipative lDad termination means for radiatirg en~rgyin a direction substantially parallel to the wave guide~
In a first embodime~t, the nondissipative load termination means includes an open end wave guide radiating load adjacent to a slot means for impedance transforming a section of ~he wave guide adjacent nonresonant slots of the traveli~g wa~e array.
More particularly, there is provided:
An antenna with a main beam comprising:
an apertured waveguide traveling wave array including a plurality of waveguide slots and a radiating load termination means for radiating electromagnetic energy in a direction parallel with said waveguide, said radiating load termination means being a radiating load termination for applying electromagnetic energy incident at the ~ " , ~33~
-2a-end of the antenna directly to the main beam of the antenna with the same polarization as the main beam so that gain of the antenna is improved, said apertured waveguide traveling wave array directly exciting said radiating load termination means so that substantially all input power into said traveling wave array is available for beam formation, and said radiating load termination being nondissipative so that substantially no electromagnetic energy is converted to heat, said radiating load termination including a quarter wave transormer having transformer 510t means for impedance transforming in a section of said waveguide adjacent said waveguide slots of said traveling wave array, said waveguide slots being nonresonant and shorter in length than said transformer means.
There is also provided:
An antenna with a main beam comprising:
an apertured waveguide traveling wave array including a plurality of waveguide ~lots and a radiating load termination means for radiating electromagnetic energy in a direction parallel with said waveguide, said xadiating load termination means being a radiating load termination for applying electro-magnetic energy at the end of the antenna directly to the main beam so that gain of the antenna is improved, said apertured waveguide traveling wave array directly exciting said radiating load termination means so that substantially all input power into said traveling wave array is available for beam forma~ion and said radiating load termination being nondissipative so that substantially no electromagnetic energy is converted to heat, ~L~33~ ~ ~
-2b-said radiating load termination including a broad wall slot means for terminating said traveling waveguide array, and a waveguide impedance matching section means adjacent said broad wall slot for providing a closed end to said waveguide and terminating a residual amount of energy, said nondissipative load termination means having a residual reflection coe~ficient 50 that there is reflected energy whose magnitude is the same and whose phase is opposite to that of a back lobe of the antenna :~`
thus cancelling the back lobe, said broad wall slot means being longer in length than said waveguide slots.
_RIEF DESCRIPTION OF THE D~AWI~
~ ig. 1 is a perspective view of an end portion o~ a txaveling wave array ~ntenna config~red in accordance wi~h a first embodimenl: of ~his invention having an open end wa~eguide radiating load;. ;~
.
.
.. . . .
:
;~33 3 ~
Fig~ 2 is a perspective ~iew of an end portion of a traveling wave~antenna array in accordance ~ith a second embodiment of this invention having a b~oad wall slot with radiating load adjacent a closed ~nd of a traveling waveguide antenna;
~ ig. 3 is a top plan view of the ~mbodiment of Fig. 2; and FigO 4 is a side elevation view of the embodiment of Fig. 2 including a coaxial tuning stub in accordance with an embodiment of this invention.
DETAILED DESCR~PTION OF THE INVENTION
Figs. 1 and 2-each show one type of nondissipative radiating load and impedance transformer sections used with a dielectric filled waveguide traveling wave array of transverse nonresonant slots in th~ broadwall of the waveguide~ The ~onfiguration shown in Fig. 1 is particularly useul for long ~raveling wave arrays, for example those ha~ing a length greater than ten times the wavelength of the signal being - radiated. The configuration shown in FigO 2 is particularly ; 20 useful for short traveling wave arrays, for example those :having a length less than ~i~e times the wavelength.
Referring first to Fig. 1, a traveling wa~e array 12 is terminated in an open end waveguide radiating load 20 preceded by three slots 21 which serve as an impedence transforming section 22 betweén radiating load 20 and the final nonresonant slots 23 of traveling wa~e array 12.
Slots 21 and 23 are closely spaced at about 0.1 wavelength or less. Slots 21 alter the ~haracteristic impedence and ~elocity of propagation of transforming section 22 and are longer t~an the slots 23 in the traveling wave array 12.
Slots 21 span appro~imately a quarter guide wavelength.
The altered waveguide characteristic impedance in impedance transformer section 22 is somewhat higher than that of the -array 12 due to the shorter array slots 23 and less than the impedance of the open end waveguide radiating load 20 ~333L:~ ~
at the end of traveling wave array 12. Thus, the waveguide section with the longer 510ts 21 (impedance transformer ~ection 22) serves as a quarter wave transformer between - ~he traveling ~ave array 12 and the radiating load 20.
To minimize the array backlo~e of traveling wave array 12, relative to an unterminated array, the transformed impedance of the radiating load should not exactly match ~he characteristic impedance of traveling wave array 12.
The transformed impedance should provide a small negative re~lection coefficient which will give rise to a small reilection lobe to cancel the backlobe of the radiating load. The need for an imperfect impedance match becomes greater as the array directivity decreases.
In a second type of -radiating load shown in Fig~ 2, a single broad wall slot 32 terminates a txaveling wave array 13 and is followed by a shorted waveguide impedance matching section 33. Such an arrangement is particularly suited to low directivity arrays which requixe an imperfect impedance match with a negative reflection coefficient (i.e., one wherein the phase is reversed) to minimize the array back-lobe. The length o radiating load slot 32 and shorted waveguide length both can be adj~sted to yield a wide range of negative reflection coefficient values to mlnimize the backlobe of traveling wave array 13 for a wide range of array directivity values~ In an electrical equivalent model the reactance of the shorted waveguide section would be in series with the impedance of the radiating load slot.
~ he traveling wave array 12 shown in Fig. 1 has ~een applied to end fire traveling wave array consisting of closely spaced, nonresonant transverse slots in a dielectric loaded waveguide. The measured gain of the array cperating at X-band was lS. 5 dB with the radiating load and 15. 2dB when a resistive load termination was used~ The 0.3 dB gain improvement represents a 0.6 dB improvement in system performance in two way active radar applications. The measured back lobe of the array relative to peak gain was -20 dB with the radiating load and -30 dB with a resistive load termination. The array was approximately 16 inches long ~13~
~ 5 ~
by 1/2 inch wide by 1/16 inch ~hick and was fabricated according to known printed circuit techniques. The absence of a resistive load termination permitted the installation.
of eight antennas on a 3-1~2 inch diameter cylinder without drilling holes into the structure at the load end of each ~ntennaJ
The traveling wave array 13 shown in Fig. 2 has been applied to a near end fire array ~beam centered 23 from end fire) of a similar design as that referred to in the previous paragraph but having lower gain than the previously dis~ussed end fire array~ The m asured gai~ of the near end fire array was 13 dB with the second type radiating load. The gain improvement attributable to the radiating loa~ was determined to be 0~ 4 dB~ The measured 1~ back lobe relative to the peak gain of the array was 15 dB.
~ he nondissipative radiating load described above radiates in a manner which contributes to forward gain, permits optimization of the back lobe level relative to an unterminated array and it does not interfere with the normal design procedure or minimizing the side lobe level of the traveling wa~e array.
Referring to Figs. 3 and 4. a traveling wave array 13a includes a coaxial tuning stub 40 which is positioned about 0.43 inches from the end of array 13a and about 0.05 25 inches off the longi~udinal axis of array 13aO The furthest edge of the radiating load slot 32a is about 0.67 inches from the end of axray 13a, and the furtherest edge of the closest of slots 31a is about 0.77 inches from end array 13a. The length of a slot 31a is about 0~292 inches, the length of slot 32a is about 0~43 inchesO The length of slots 31a goes down to about 0.22 inches at the left end of array 13a. In contrast, the total width of array 13a increases from a right width of about 0.455 inches to a left width of a~out 0.513 inches. The left coaxial input terminal 35 41 is positioned about 0.116 inches off center and about - 0.49 inches from tne left end array 13. The thickness of array 13 is about 0.062 inches. ~he to~al length of array ~33~ ~ ~
~ ~ o 13a is about 5~12 inches and the length containing slots 31a along array 13a is 3.7 inches.
The shor~ circuited waveguide serves as a reactive tUning element which primarily affects only the last slot in a manner which causes this slot to radiate all of the remaining energy which was not radiated by the traveling wave array and to suppress the s~anding wave which would otherwise .. .. .. . . . .
occur within the waveguide. In practice, the radiating load termi~ation produces a small residual reflection coefficient 10 whose magnitude is the same and whose phase is opposite to that of the back lobe. Thus r the reflection coef ficient cancels the baok lobe. In other words, the amount of energy which is reflected due to the reflection coefficient is egual to the normal back lobe of the traveling wave axray, I5 thus allowing the enersy of the radiating load to be added to the main beam.
With respect to Fig. 1, an open end waveguiae radiating load is preceded by ~hree slots which serve as an impedance transforming section terminating the final non-20 resonant slots of the traveling wave array. The slots alterthe characteristic impedance and velocity of propagation of the waveguide. The waveguide characteristic impedance in the transforming section will be somewhat higher than that o the shorter array slots and less than ~he impedance of ~he 2~ open end waveguide radiating load. Thus, the waveguide section with ~he longer slots serves as a quarter wav~ trans-former between the traveling wave array and the radiating load. As is well known in the art~ a ~uarter wave trans~
former can couple any impedance with another impedance. In 30 Fig. 2, the radiating load consists of a single broad wall slo~ terminating the traveling wave array, followed by a shorted waveguide impedance matching sectionO
Various modifications and variations will no doubt occur to those s~illed in the various arts to which this ~5 invention pertains. For example, the particular radiating loads transformer sections and traveling wave arrays may be varied from those described herein~ These and all other o 7 variations which basically rely on the teachings through which this disclosure has advanced the art are properly considered within the scope of this invention.
o ..
Claims (3)
1. An antenna with a main beam comprising:
an apertured waveguide traveling wave array including a plurality of waveguide slots and a radiating load termination means for radiating electromagnetic energy in a direction parallel with said waveguide, said radiating load termination means being a radiating load termination for applying electromagnetic energy incident at the end of the antenna directly to the main beam of the antenna with the same polarization as the main beam so that gain of the antenna is improved, said apertured waveguide traveling wave array directly exciting said radiating load termination means so that substantially all input power into said traveling wave array is available for beam formation, and said radiating load termination being nondissipative so that substantially no electromagnetic energy is converted to heat, said radiating load termination including a quarter wave transformer having transformer slot means for impedance transforming in a section of said waveguide adjacent said waveguide slots of said traveling wave array, said waveguide slots being nonresonant and shorter in length than said transformer means.
an apertured waveguide traveling wave array including a plurality of waveguide slots and a radiating load termination means for radiating electromagnetic energy in a direction parallel with said waveguide, said radiating load termination means being a radiating load termination for applying electromagnetic energy incident at the end of the antenna directly to the main beam of the antenna with the same polarization as the main beam so that gain of the antenna is improved, said apertured waveguide traveling wave array directly exciting said radiating load termination means so that substantially all input power into said traveling wave array is available for beam formation, and said radiating load termination being nondissipative so that substantially no electromagnetic energy is converted to heat, said radiating load termination including a quarter wave transformer having transformer slot means for impedance transforming in a section of said waveguide adjacent said waveguide slots of said traveling wave array, said waveguide slots being nonresonant and shorter in length than said transformer means.
2. An antenna as recited in Claim 1 wherein said impedance transforming section includes three slots, adjacent slots being separated by the distance of 0.1 wavelengths or less.
3. An antenna with a main beam comprising:
an apertured waveguide traveling wave array including a plurality of waveguide slots and a radiating load termination means for radiating electromagnetic energy in a direction parallel with said waveguide, said radiating load termination means being a radiating load termination for applying electro-magnetic energy at the end of the antenna directly to the main beam so that gain of the antenna is improved, said apertured waveguide traveling wave array directly exciting said radiating load termination means so that substantially all input power into said traveling wave array is available for beam formation and said radiating load termination being nondissipative so that substantially no electromagnetic energy is converted to heat, said radiating load termination including a broad wall slot means for terminating said traveling waveguide array, and a waveguide impedance matching section means adjacent said broad wall slot for providing a closed end to said waveguide and terminating a residual amount of energy, said nondissipative load termination means having a residual reflection coefficient so that there is reflected energy whose magnitude is the same and whose phase is opposite to that of a back lobe of the antenna thus cancelling the back lobe, said broad wall slot means being longer in length than said waveguide slots.
an apertured waveguide traveling wave array including a plurality of waveguide slots and a radiating load termination means for radiating electromagnetic energy in a direction parallel with said waveguide, said radiating load termination means being a radiating load termination for applying electro-magnetic energy at the end of the antenna directly to the main beam so that gain of the antenna is improved, said apertured waveguide traveling wave array directly exciting said radiating load termination means so that substantially all input power into said traveling wave array is available for beam formation and said radiating load termination being nondissipative so that substantially no electromagnetic energy is converted to heat, said radiating load termination including a broad wall slot means for terminating said traveling waveguide array, and a waveguide impedance matching section means adjacent said broad wall slot for providing a closed end to said waveguide and terminating a residual amount of energy, said nondissipative load termination means having a residual reflection coefficient so that there is reflected energy whose magnitude is the same and whose phase is opposite to that of a back lobe of the antenna thus cancelling the back lobe, said broad wall slot means being longer in length than said waveguide slots.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US6208779A | 1979-07-30 | 1979-07-30 | |
| US62,087 | 1979-07-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1133119A true CA1133119A (en) | 1982-10-05 |
Family
ID=22040137
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA348,990A Expired CA1133119A (en) | 1979-07-30 | 1980-04-01 | Nondissipative load termination for traveling wave array antenna |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1133119A (en) |
| DE (1) | DE3028730A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61167203A (en) * | 1985-01-21 | 1986-07-28 | Toshio Makimoto | Plane antenna |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2880417A (en) * | 1955-02-11 | 1959-03-31 | Lockheed Aircraft Corp | Traveling wave device |
| US2994874A (en) * | 1959-07-23 | 1961-08-01 | Kihn Harry | High-speed, narrow beam radar scanning antenna |
| US3328800A (en) * | 1964-03-12 | 1967-06-27 | North American Aviation Inc | Slot antenna utilizing variable standing wave pattern for controlling slot excitation |
| GB1503664A (en) * | 1975-05-09 | 1978-03-15 | Decca Ltd | Microwave antenna |
-
1980
- 1980-04-01 CA CA348,990A patent/CA1133119A/en not_active Expired
- 1980-07-29 DE DE19803028730 patent/DE3028730A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE3028730C2 (en) | 1988-02-04 |
| DE3028730A1 (en) | 1981-03-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |