Patent Grant
7019603
This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/JP03/03099 which has an International filing date of Mar. 14, 2003, which designated the United States of America.
The present invention relates to a waveguide type polarizer mainly used in a VHF band, a UHF band, a microwave band and a millimeter wave band.
In
Next, an operation will hereinbelow be described. For a basic mode (TE01-mode) of the horizontally polarized electric wave H inputted through the terminal P1 of the main waveguide 31, each of a space defined between an upper sidewall of the main waveguide 31 and the metallic thin plate 33a, a space defined between the metallic thin plates 33a and 33b, and a space defined between the metallic thin plate 33b and a lower sidewall of the main waveguide 31 is designed so as to be equal to or smaller than a half of a free-space wavelength of a frequency band in use. Thus, the horizontally polarized electric wave H hardly leaks to the terminal P2 side of the main waveguide 31 due to those cut-off effects.
In addition, since as shown in
Moreover, the two metallic thin plates 33a and 33b have the same shape, take a vertically symmetrical shape within the main waveguide 31 and are mounted in positions away from the vicinity of a center. Thus, as shown in
On the other hand, for a vertically polarized electric wave V of a basic mode (TE10-mode) inputted through the terminal P1 of the main waveguide 31, each of a sidewall space defined between surfaces each having a large width of the branching waveguide 32a and a sidewall space defined between surfaces each having a large width of the branching waveguide 32b is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the vertically polarized electric wave hardly leaks to the sides of the terminal P3 and the terminal P4 of the branching waveguides 32a and 32b due to those cut-off effects.
In addition, the metallic thin plates 33a and 33b are mounted so that the plate surfaces thereof perpendicularly intersect a direction of an electric field of the vertically polarized wave V in the main waveguide 31, and also a thickness of each of the metallic thin plates 33a and 33b is designed so as to be much smaller than the free-space wavelength of the frequency band in use. For this reason, the electric wave V of the basic mode is hardly reflected by the metallic thin plates 33a and 33b. Therefore, the vertically polarized electric wave V of the basic mode inputted through the terminal P1 is efficiently outputted to the terminal P2 while suppressing the reflection to the terminal P1 and the leakage to the terminals P3 and P4.
The conventional waveguide type polarizer is constituted by: the rectangular main waveguide 31; the two rectangular branching waveguides 32a and 32b branching perpendicularly and symmetrically with respect to the tube axis of the main waveguide 31; and the metallic thin plates 32a and 32b inserted into the main waveguide 31. Then, the vertically polarized wave and the horizontally polarized wave which have entered through the input terminal P1 of the main waveguide 31 are outputted through the output terminal P2 of the main waveguide 31 and the output terminals P3 and P4 of the branching waveguides 32a and 32b, respectively. Thus, there arises a problem in that a miniaturization, and shortening of the axis are difficult to be made with respect to a direction of the tube axis of the main waveguide 31.
In addition, in general, in a frequency band in the vicinity of the cut-off frequencies of the basic modes (the TE10-mode and the TE01-mode) of the vertically polarized wave and the horizontally polarized wave, an abrupt change in frequency of a guide wavelength is observed, and along therewith, an abrupt change in frequency of discontinuity of an impedance in the branch portion of the rectangular waveguide 31 is also involved. Thus, in the conventional waveguide type polarizer, it is difficult to suppress the degradation of the reflection characteristics of both the polarized waves in a frequency band in the vicinity of the cut-off frequencies.
The present invention has been made in order to solve the problems as described above, and it is therefore an object of the present invention to obtain a waveguide type polarizer, which enables a miniaturization thereof, shortening of an axis, and broad band promotion, and which has high performance.
A waveguide type polarizer according to an aspect of the present invention includes: a first rectangular main waveguide; first to fourth rectangular branching waveguides branching perpendicularly to the first rectangular main waveguide; a short-circuit plate connected to one terminal of the first rectangular main waveguide; a metallic projection provided on the short-circuit plate; a rectangular waveguide step connected to the other terminal of the first rectangular main waveguide; and a second rectangular main waveguide connected to the rectangular waveguide step.
Also, a waveguide type polarizer according to another aspect of the present invention includes: a first rectangular main waveguide; first to fourth rectangular branching waveguides branching perpendicularly to the first rectangular main waveguide; a short-circuit plate connected to one terminal of the first rectangular main waveguide; a metallic projection provided on the short-circuit plate; a circular-rectangular waveguide step connected to the other terminal of the first rectangular main waveguide; and a circular main waveguide connected to the circular-rectangular waveguide step.
Further, a waveguide type polarizer according to another aspect of the present invention includes: a first rectangular main waveguide; first and second rectangular branching waveguides branching perpendicularly to the first rectangular main waveguide; first and second conductor thin plates which are mounted in a pair in symmetrical positions within the first rectangular main waveguide; a rectangular waveguide step which is connected to the other terminal of the first rectangular main waveguide, and has an opening diameter that is decreased toward a branch portion of the first rectangular main waveguide for the first and second rectangular branching waveguides; and a second rectangular main waveguide connected to the rectangular waveguide step.
Hereinafter, an embodiment mode of the present invention will be described.
In
Next, an operation will hereinbelow be described. Now, assuming that the horizontally polarized electric wave H of a basic mode (TE01-mode) is inputted through the terminal P1, this electric wave is propagated through the square waveguide step 5, the square main waveguide 1, and the rectangular branching waveguides 2a and 2b to be outputted in the form of electric waves of a basic mode (TE10-mode) in each branching waveguide through the terminals P2 and P3, respectively.
Here, for the electric wave H, each of spaces defined between upper and lower sidewalls of the rectangular branching waveguides 2c and 2d is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the electric wave H hardly leaks to the sides of the terminals P4 and P5 due to the cut-off effect of those spaces. In addition, since a direction of the electric field can be changed along the metallic block 4 and the short-circuit plate 3 as shown in
Moreover, the square waveguide step 5 is designed such that a stepped portion thereof is much smaller than the free-space wavelength of the frequency band in use. For this reason, with respect to the reflection characteristics thereof, a reflection loss is large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave H, while it is very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to reflection characteristics of the above-mentioned branch portion. Therefore, the square waveguide step 5 is installed in a position where a reflected wave from the branch portion and a reflected wave due to the square waveguide step 5 cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to suppress a degradation of the reflection characteristics in the frequency band in the vicinity of the cut-off frequency without impairing a satisfactory reflection characteristics in the frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave H to some extent.
On the other hand, assuming that the vertically polarized wave V of the basic mode (TE10-mode) is inputted through the terminal P1, this electric wave is propagated through the square waveguide step 5, the square main waveguide 1 and the rectangular branching waveguides 2c and 2d to be outputted in the form of electric waves of the basic mode (TE10-mode) in each branching waveguide through the terminals P4 and P5, respectively.
Here, for the electric wave V, each of spaces defined between upper and lower sidewalls of the rectangular branching waveguides 2a and 2b is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the electric wave V hardly leaks to the sides of the terminals P2 and P3 due to the cut-off effect of those spaces. In addition, since a direction of the electric field is changed along the metallic block 4 and the short-circuit plate 3 as shown in
Moreover, the square waveguide step 5 is designed such that a stepped portion thereof is much smaller than the free-space wavelength of the frequency band in use. Thus, with respect to the reflection characteristics thereof, a reflection loss is large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave V, while it is very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to the reflection characteristics of the above-mentioned branch portion. Therefore, the square waveguide step 5 is installed in a position where a reflected wave from the branch portion and a reflected wave due to the square waveguide step 5 cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to suppress the degradation of the reflection characteristics in the frequency band in the vicinity of the cut-off frequency without impairing the satisfactory reflection characteristics in the frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave H to some extent.
The above-mentioned operation principles have been described with respect to the case where the terminal P1 is determined as an input terminal, and the terminals P2 to P5 are set as output terminals. However, the above-mentioned operation principles are applied to a case as well where the terminals P2 to P5 are determined as input terminals, the terminal P1 is determined as an output terminal, input waves inputted through the terminals P2 and P3 are made 180 degrees out of phase with each other and are made equal in amplitude to each other, and input waves inputted through the terminals P4 and P5 are made 180 degrees out of phase with each other and are made equal in amplitude to each other.
As described above, according to Embodiment Mode 1, the polarizer is constituted by: the first and second square main waveguides; the first to fourth rectangular branching waveguides; the short-circuit plate for shutting one terminal of the square main waveguide; the square pyramid-like metallic block provided on the short-circuit plate; and the square waveguide step which is sandwiched between the first square main waveguide and the second square main waveguide, and has an opening diameter that is increased toward the branch portion. Thus, an effect is obtained in that it is possible to realize satisfactory reflection characteristics and isolation characteristics in a broad frequency band including the vicinity of the cut-off frequency of the basic mode of the square main waveguide.
In addition, since the four rectangular branching waveguides branches perpendicularly and symmetrically with respect to the tube axis of the square main waveguide, an effect is obtained in that miniaturization can be promoted for a direction of the tube axis of the square main waveguide.
Moreover, since a construction is adopted in which a metallic thin plate and a metallic post are not used, an effect is obtained in that a level of difficulty for processing can be lowered, with the result that the cost reduction promotion can be realized.
Note that, while in Embodiment Mode 1, the description has been given of the case where the square pyramid-like metallic block 4 is provided as a metallic projection for changing a direction of an electric field as shown in
Next, an operation will hereinbelow be described. Now, assuming that the horizontally polarized electric wave H of a basic mode (TE01-mode) is inputted through the terminal P1, this electric wave is propagated through the circular-square waveguide step 9, the square main waveguide 8, the square waveguide step 7, the square main waveguide 1, and the rectangular branching waveguides 2a and 2b to be outputted in the form of electric waves of a basic mode (TE10-mode) in each branching waveguide through the terminals P2 and P3, respectively.
Here, for the electric wave H, each of spaces defined between upper and lower sidewalls of the rectangular branching waveguides 2c and 2d is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the electric wave H hardly leaks to the sides of the terminals P4 and P5 due to the cut-off effect of those spaces. In addition, since a direction of the electric field is changed along the metallic block 4 and the short-circuit plate 3 as shown in
Furthermore, the circular-square waveguide step 9, the square main waveguide 8, and the square waveguide step 7 are operated in the form of a circular-rectangular waveguide multistage transformer. For this reason, a diameter of the circular main waveguide 10, a diameter of the square main waveguide 8, and a length of the tube axis of the square main waveguide 8 are suitably designed, so that as the reflection characteristics of the multistage transformer, a reflection loss can be made large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave H, while it is can be made very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to the reflection characteristics of the above-mentioned branch portion. Therefore, the square waveguide step 7 and the circular-square waveguide step 9 are installed in positions where a reflected wave from the branch portion, and reflected waves due to the square waveguide step 7 and the circular-square waveguide step 9 cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to suppress the degradation of the reflection characteristics in a frequency band in the vicinity of the cut-off frequency without impairing the excellent reflection characteristics in a frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave H to some extent.
On the other hand, assuming that the vertically polarized electric wave V of a basic mode (TE10-mode) is inputted through the terminal P1, this electric wave is propagated through the circular-square waveguide step 9, the square main waveguide 8, the square waveguide step 7, the square main waveguide 1, and the rectangular branching waveguides 2c and 2d to be outputted in the form of electric waves of a basic mode (TE10-mode) in each branching waveguide through the terminals P4 and P5, respectively.
Here, for the electric wave V, each of spaces defined between upper and lower sidewalls of the rectangular branching waveguides 2a and 2b is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the electric wave V hardly leaks to the sides of the terminals P2 and P3 due to the cut-off effect of those spaces. In addition, since a direction of the electric field is changed along the metallic block 4 and the short-circuit plate 3 as shown in
Furthermore, the circular-square waveguide step 9, the square main waveguide 8, and the square waveguide step 7 are operated in the form of a circular-rectangular waveguide multistage transformer. For this reason, a diameter of the circular main waveguide 10, a diameter of the square main waveguide 8, and a length of the tube axis of the square main waveguide 8 are suitably designed, whereby as the reflection characteristics of the multistage transformer, a reflection loss can be made large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave V, while it is can be made very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to the reflection characteristics of the above-mentioned branch portion. Therefore, the square waveguide step 7 and the circular-square waveguide step 9 are installed in positions where a reflected wave from the branch portion, and reflected waves due to the square waveguide step 7 and the circular-square waveguide step 9 cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to suppress the degradation of the reflection characteristics in a frequency band in the vicinity of the cut-off frequency without impairing the excellent reflection characteristics in a frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave V to some extent.
The above-mentioned operation principles have been described with respect to the case where the terminal P1 is determined as an input terminal, and the terminals P2 to P5 are determined as output terminals. However, the above-mentioned operation principles are applied to a case where the terminals P2 to P5 are determined as input terminals, the terminal P1 is determined as an output terminal, input waves inputted through the terminals P2 and P3 are made 180 degrees out of phase with each other and are made equal in amplitude to each other, and input waves inputted through the terminals P4 and P5 are made 180 degrees out of phase with each other and are made equal in amplitude to each other.
As described above, according to Embodiment Mode 2, the polarizer is constituted by: the first and second square main waveguides; the one circular main waveguide; the first to fourth rectangular branching waveguides; the short-circuit plate for shutting one terminal of the first square main waveguide; the square pyramid-like metallic block provided on the short-circuit plate; the square waveguide step which is sandwiched between the first square main waveguide and the second square main waveguide and has an opening diameter that is decreased toward the branch portion; and the circular-square waveguide step sandwiched between the second square main waveguide and the circular main waveguide. Thus, an effect is obtained in that the excellent reflection characteristics and isolation characteristics can be realized in a broad frequency band including the vicinity of the cut-off frequency of the basic mode in the square main waveguide.
In addition, since the four rectangular branching waveguides branch perpendicularly and symmetrically with respect to the tube axis of the square main waveguide, an effect is obtained in that miniaturization can be performed for a direction of the tube axis of the square main waveguide.
In addition, since the opening shape of the waveguide for the input terminal is circular, when this polarizer and a circular horn antenna primary radiator are combined with each other for use, excellent impedance matching is obtained between those components. Therefore, an effect is obtained in that the reduction of an impedance transformer which is normally provided between a polarizer and an antenna primary radiator can be performed to thereby realize further miniaturization.
Moreover, since a construction is adopted in which a metallic thin plate and a metallic post are not used, an effect is obtained in that the level of difficulty for processing can be lowered, with the result that the cost reduction promotion can be realized.
In Embodiment Mode 2 above, the description has been given of the waveguide type polarizer in which the square pyramid-like metallic block 4 is provided as the metallic projection on the short-circuit plate 3. However, if as shown in
Next, an operation will hereinbelow be described. Now, assuming that the horizontally polarized electric wave H of a basic mode (TE01-mode) is inputted through the terminal P1, this electric wave is propagated through the square waveguide step 5, the square main waveguide 1, the rectangular branching waveguides 2a and 2b, and the rectangular waveguide multistage transformers 11a and 11b to compose the separated electric waves again in the rectangular waveguide E-plane T-junction 12a to output the composite electric wave in the form of an electric wave of a basic mode (TE10-mode) in each branching waveguide through the terminal P2.
Here, for the electric wave H, each of spaces defined between upper and lower sidewalls of the rectangular branching waveguides 2c and 2d is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the electric wave H hardly leaks to the sides of the rectangular waveguides 2c and 2d due to the cut-off effect of those spaces. In addition, since a direction of an electric field is changed along the metallic block 4 and the short-circuit plate 3 as shown in
Moreover, the square waveguide step 5 is designed such that a stepped portion thereof is much smaller than the free-space wavelength of the frequency band in use. Thus, with respect to the reflection characteristics thereof, a reflection loss is large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave H, while the reflection loss is very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to the reflection characteristics of the above-mentioned branch portion. Therefore, the square waveguide step 5 is installed in a position where a reflected wave from the branch portion and a reflected wave due to the square waveguide step 5 cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to suppress degradation of the reflection characteristics in a frequency band in the vicinity of the cut-off frequency without impairing the excellent reflection characteristics in the frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave H to some extent.
Furthermore, each of the rectangular waveguide multistage transformers 11a and 11b has a curved tube axis, and has a plurality of stepped portions provided on an upper sidewall surface thereof, and also each of intervals of the stepped portions becomes about ¼ of a guide wavelength with respect to a waveguide central line. Thus, finally, electric waves in the rectangular branching waveguides 2a and 2b which are obtained by separating the electric wave H can be composed in the rectangular waveguide E-plane T-junction 12a and the composite electric wave can be efficiently outputted to the terminal P2 without impairing the reflection characteristics.
On the other hand, assuming that the vertically polarized electric wave V of a basic mode (TE10-mode) is inputted through the terminal P1, this electric wave is propagated through the square waveguide step 5, the square main waveguide 1, the rectangular branching waveguides 2c and 2d, and the rectangular waveguide multistage transformers 11c and 11d to compose the separated electric waves in the rectangular waveguide E-plane T-junction 12b to output the composite wave in the form of an electric wave of a basic mode (TE10-mode) in each branching waveguide through the terminal P3.
Here, for the electric wave V, each of spaces defined between upper and lower sidewalls of the rectangular branching waveguides 2a and 2b is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the electric wave V hardly leaks to the sides of the rectangular waveguides 2a and 2b due to the cut-off effect of those spaces. In addition, since a direction of an electric field is changed along the metallic block 4 and the short-circuit plate 3 as shown in
Moreover, the square waveguide step 5 is designed such that a stepped portion thereof is much smaller than the free-space wavelength of the frequency band in use. Thus, with respect to the reflection characteristics thereof, a reflection loss is large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave V, while the reflection loss is very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to the reflection characteristics of the above-mentioned branch portion. Therefore, the square waveguide step 5 is installed in a position where a reflected wave from the branch portion and a reflected wave due to the square waveguide step 5 cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to suppress degradation of the reflection characteristics in a frequency band in the vicinity of the cut-off frequency without impairing the excellent reflection characteristics in the frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave V to some extent.
Furthermore, each of the rectangular waveguide multistage transformers 11c and 11d has a curved tube axis, and has a plurality of stepped portions provided on a lower sidewall surface thereof, and also each of intervals of the stepped portions becomes about ¼ of a guide wavelength with respect to a waveguide central line. Thus, finally, electric waves in the rectangular branching waveguides 2c and 2d which are obtained by separating the electric wave V can be composed in the rectangular waveguide E-plane T-junction 12b so as to avoid interference with the rectangular waveguide multistage transformers 11a and 11b, and the rectangular waveguide E-plane T-junction 12a, and the composite electric wave can be efficiently outputted to the terminal P3 without impairing the reflection characteristics.
The above-mentioned operation principles have been described with respect to the case where the terminal P1 is determined as an input terminal, and the terminals P2 and P3 are determined as output terminals. However, the above-mentioned operation principles are also applied to a case where the terminals P2 and P3 are determined as input terminals, and the terminal P1 is determined as an output terminal.
As described above, according to Embodiment Mode 4, the polarizer is constituted by: the first and second square main waveguides; the first to fourth rectangular branching waveguides branching perpendicularly and symmetrically with respect to a tube axis of the first square main waveguide; the short-circuit plate for shutting one terminal of the first square main waveguide; the square pyramid-like metallic block provided on the short-circuit plate; the square waveguide step which is sandwiched between the first square main waveguide and the second square main waveguide, and has an opening diameter that is increased toward the branch portion; the first and second rectangular waveguide multistage transformers which are respectively connected to the first and second rectangular branching waveguides, each of which has a curved tube axis, and each of which has a plurality of stepped portions provided on an upper sidewall surface thereof; the third and fourth rectangular waveguide multistage transformers which are respectively connected to the third and fourth rectangular branching waveguides, each of which has a curved tube axis, and each of which has a plurality of stepped portions provided on a lower sidewall surface thereof; and the first and second rectangular waveguide E-plane T-junctions. Thus, an effect is obtained in that the excellent reflection characteristics and isolation characteristics can be realized in a broad frequency band including the vicinity of the cut-off frequency of the basic mode of the square main waveguide.
In addition, an effect is obtained in that with respect to the whole polarizer including a composition circuit portion for composing the horizontally polarized waves H and the vertically polarized electric waves V, respectively, which are separated through the four rectangular branching waveguides, the miniaturization can be promoted for the direction of the tube axis of the square main waveguide.
Moreover, since a construction is adopted in which a metallic thin plate and a metallic post are not used, an effect is obtained in that the level of difficulty in processing can be lowered, with the result that the cost reduction promotion can be realized.
In Embodiment Mode 4 above, the description has been made of the waveguide type polarizer provided with: the first square main waveguide 1; the second square main waveguide 6; the first to fourth rectangular branching waveguides 2a to 2d branching perpendicularly and symmetrically with respect to the tube axis of the square main waveguide 1; the short-circuit plate 3 for shutting one terminal of the square main waveguide 1; the square pyramid-like metallic block 4 provided on the short-circuit plate 3; the square waveguide step 5 which is sandwiched between the square main waveguide 1 and the square main waveguide 6, and has an opening diameter that is increased toward the branch portion; the first rectangular waveguide multistage transformer 11a which is connected to the rectangular branching waveguide 2a, which has a curved tube axis, and which has a plurality of stepped portions provided on an upper sidewall surface thereof; the second rectangular waveguide multistage transformer 11b which is connected to the rectangular branching waveguide 2b, each of which has a curved tube axis, and each of which has a plurality of stepped portions provided on an upper sidewall surface thereof; the third rectangular waveguide multistage transformer 11c which is connected to the rectangular branching waveguide 2c, each of which has a curved tube axis, and each of which has a plurality of stepped portions provided on a lower sidewall surface thereof; the fourth rectangular waveguide multistage transformer 11d which is connected to the rectangular branching waveguide 2d, each of which has a curved tube axis, and each of which has a plurality of stepped portions provided on a lower sidewall surface thereof; and the first and second rectangular waveguide E-plane T-junctions 12a and 12b. However, in this Embodiment Mode 5, as shown in
Conventionally, when a waveguide circuit is constructed, components need to be connected to one another with flanges. Then, since an occupancy area of the flange portion is much larger than the size of a waveguide, the occupancy area of the flanges is also increased all the more since if the number of components is increased, the number of flanges is also increased in proportion to that number. However, according to this Embodiment Mode 5, since the components obtained through the digging processing have only to be combined with one another, connection supporting mechanisms such as the flanges and the like required for connection among the components are greatly reduced. Hence, an effect is obtained in that the miniaturization can be largely promoted with respect to the direction of the tube axis of the square main waveguide.
In
Next, an operation will hereinbelow be described. Now, assuming that the horizontally polarized electric wave H of a basic mode (TE01-mode) is inputted through the terminal P1, this electric wave is propagated through the square waveguide step 19, the square main waveguide 16, the group of metallic posts 21a and 21b, the rectangular branching waveguides 17a and 17b, the rectangular waveguide steps 22a and 22b, and the rectangular branching waveguides 23a and 24b to be outputted in the form of electric waves of a basic mode (TE10-mode) in each branching waveguide through the terminals P3 and P4, respectively.
Here, for the electric wave H, each of a space defined between an upper sidewall of the square main waveguide 16 and the metallic thin plate 18a, a space defined between the metallic thin plates 18a and 18b, and a space defined between the metallic thin plate 18b and a lower sidewall of the main waveguide 16 is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the electric wave H hardly leaks to the side of the terminal P2 of the square main waveguide 16 due to the cut-off effect of those spaces. In addition, since a direction of the electric field is changed along the metallic thin plates 18a and 18b as shown in
In addition, the metallic thin plates 18a and 18b have the same shape, and are vertically symmetrical within the square main waveguide 16, and also are mounted in positions apart from the vicinity of the center. For this reason, as shown in
Moreover, the square waveguide step 19 is designed such that a stepped portion thereof is much smaller than the free-space wavelength of the frequency band in use. Thus, with respect to the reflection characteristics thereof, a reflection loss is large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave H, while the reflection loss is very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to the reflection characteristics of the above-mentioned branch portion. Therefore, the square waveguide step 19 is installed in a position where a reflected wave from the branch portion and a reflected wave due to the square waveguide step 19 cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to improve the reflection characteristics in a frequency band in the vicinity of the cut-off frequency without impairing the excellent reflection characteristics in the frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave H.
Likewise, each of the rectangular waveguide steps 22a and 22 is designed such that a stepped portion thereof is much smaller than the free-space wavelength of the frequency band in use. Thus, with respect to the reflection characteristics thereof, a reflection loss is large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave H, while the reflection loss is very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to the reflection characteristics of the above-mentioned branch portion. Therefore, the rectangular waveguide steps 22a and 22b are installed in positions where a reflected wave from the branch portion and reflected waves due to the rectangular waveguide steps 22a and 22b cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to further improve the reflection characteristics in the frequency band in the vicinity of the cut-off frequency without impairing the excellent reflection characteristics in the frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave H.
On the other hand, assuming that the vertically polarized electric wave V of a basic mode (TE10-mode) is inputted through the terminal P1, this electric wave is propagated through the square waveguide step 19, and the square main waveguide 16 to be outputted in the form of an electric wave of a basic mode (TE10-mode) in the square waveguide through the terminal P2.
Here, for the electric wave V, each of spaces defined between upper and lower sidewalls of the rectangular branching waveguides 17a and 17b is designed so as to be equal to or smaller than a half of the free-space wavelength of the frequency band in use. Thus, the electric wave V hardly leaks to the sides of the terminals P3 and P4 due to the cut-off effect of those spaces. In addition, since the surfaces each having a large width of the metallic thin plates 18a and 18b perpendicularly intersect a direction of the electric field of the basic mode of the electric wave V and a thickness of each metallic thin plate is much smaller than the free-space wavelength, no reflection characteristics of the electric wave V is impaired. Thus, the electric wave V inputted through the terminal P1 is efficiently outputted to the terminal P2 while suppressing the reflection to the terminal P1 and the leakage to the terminals P3 and P4.
In addition, the leakage of the electric wave of an unnecessary higher mode generated in the branch portion when making the vertically polarized electric wave V incident to the sides of the rectangular branching waveguides 17a and 17b is cut off by the group of metallic posts 21a and 21b. Hence, the disturbance of the electromagnetic field in the vicinity of the branch portion is suppressed, and finally, the excellent reflection characteristics are obtained over a broad band.
Furthermore, the square waveguide step 19 is designed such that a stepped portion thereof is much smaller than the free-space wavelength of the frequency band in use. Thus, with respect to the reflection characteristics thereof, a reflection loss is large in a frequency band in the vicinity of the cut-off frequency of the basic mode of the electric wave V, while the reflection loss is very small in a frequency band any frequency of which is higher than the cut-off frequency to some extent. This is similar to the reflection characteristics of the above-mentioned branch portion. Therefore, the square waveguide step 19 is installed in a position where a reflected wave from the branch portion and a reflected wave due to the square waveguide step 19 cancel each other in the vicinity of the cut-off frequency, so that it becomes possible to suppress the degradation of the reflection characteristics in the frequency band in the vicinity of the cut-off frequency without impairing the excellent reflection characteristics in the frequency band any frequency of which is higher than the cut-off frequency of the basic mode of the electric wave V.
The above-mentioned operation principles have been described with respect to the case where the terminal P1 is determined as an input terminal, and the terminals P2 to P4 are determined as output terminals. However, the above-mentioned operation principles are also applied to a case where the terminals P2 to P4 are determined as input terminals, the terminal P1 is determined as an output terminal, and the input waves which have been respectively inputted through the terminals P3 and P4 are made 180 degrees out of phase with each other and are made equal in amplitude to each other.
As described above, according to this Embodiment Mode 6, the polarizer is constituted by: the first and second square main waveguides; the first and second rectangular branching waveguides branching perpendicularly and symmetrically with respect to the tube axis of the first square main waveguide; the metallic thin plates which are inserted into the first square main waveguide and which each have the arcuate cutouts symmetrically formed; the square waveguide step which is sandwiched between the first square main waveguide and the second square main waveguide, and the opening diameter of which is decreased toward the branch portion; the first and second group of metallic posts which are respectively mounted within the first and second rectangular branching waveguides; the third and fourth rectangular branching waveguides; and the first and second rectangular waveguide steps which are sandwiched between the first and second rectangular branching waveguides, and the third and fourth rectangular branching waveguides, and the opening diameter of each of which is decreased toward the branch portion. Thus, an effect is obtained in that the excellent reflection characteristics and isolation characteristics can be realized in a very broad frequency band including the vicinity of the cut-off frequency of the basic mode of the square main waveguide, and the vicinity of a frequency which is twice as high as the cut-off frequency.
In Embodiment Mode 1 above, the description has been given of the waveguide type polarizer provided with the square waveguide step 5 which is connected to one terminal of the square main waveguide 1, and the opening diameter of which is increased toward the above-mentioned branch portion, and also the stepped portion of which is much smaller than the free-space wavelength of the frequency band in use. However, if as shown in
In Embodiment Mode 1 above, the description has been given of the waveguide type polarizer provided with the square waveguide step 5 which is connected to one terminal of the square main waveguide 1, and the opening diameter of which is increased toward the above-mentioned branch portion, and also the stepped portion of which is much smaller than the free-space wavelength of the frequency band in use. However, if as shown in
As set forth, according to the present invention, it is possible to obtain the waveguide type polarizer, which enables miniaturization thereof, shortening of an axis, and broad band promotion, and which has high performance.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-078178 | Mar 2002 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP03/03099 | 3/14/2003 | WO | 00 | 10/21/2003 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO03/079483 | 9/25/2003 | WO | A |
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| Number | Date | Country | |
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| 20040246069 A1 | Dec 2004 | US |
