JPH04257101A - Cross polarization demultiplexing device - Google Patents

Abstract

PURPOSE:To shorten the axial length of a main waveguide. CONSTITUTION:A waveguide part 2 for high frequency band and a waveguide part 3 for low frequency band are formed in one end of a rectangular waveguide 1. Both waveguide parts share one end of the rectangular waveguide 1 and are arranged on a line orthogonal to the axis of the rectangular waveguide so that respective input/output ports are opposite to each other. That is, one end of the rectangular waveguide 1 is matched and connected to a demultiplexing waveguide 5 with a 45 deg. corner wall 4 in the electric field face between them to form the waveguide part 2 for high frequency band, and an E face 90 deg. bent waveguide is formed as the whole. A coupling window 6 is provided in the center of the corner wall 4, and a demultiplexing waveguide 7 is matched and connected to one end of the rectangular waveguide 1 with a quarter-wave transformer 8 and the coupling window 6 between them to form the waveguide part 3 for low frequency band, and an H face corner 90 deg. bent waveguide is formed as a whole.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide-type orthogonal polarization splitter for microwave bands and sub-millimeter wave bands.

0002

[Prior Art] A conventional waveguide-type orthogonal polarization splitter that utilizes orthogonality of polarization is installed on the tube wall of a main waveguide (rectangular waveguide or circular waveguide) that is shared by two frequencies. There are many structures in which the excitation is performed while maintaining an orthogonal polarization relationship with each other through an open coupling window and a transformer. For an orthogonal polarization splitter having such a structure, a low-order splitting method is effective in which the waves are sequentially split from low frequencies by utilizing the cutoff characteristics of the waveguide for the fundamental mode wave. In other words, the conventional orthogonal polarization splitter has a structure in which a branch waveguide for high frequencies is cascade-connected to a main waveguide for dual frequencies with the same tube axis.

0003

Therefore, in the conventional orthogonal polarization splitter, the length in the tube axis direction increases, and it is difficult to shorten the axial length and make it more compact. In particular, in the field of satellite communications, communication satellites have recently become more powerful and have a larger capacity, and the construction of so-called distributed networks in which micro-earth stations communicate directly via communication satellites has progressed rapidly. I am, but
For small antennas used in this type of earth station, an orthogonal polarization splitter that is compact and has high cost performance characteristics is essential, and its development is desired.

[0004] The purpose of the present invention is to simplify and downsize the structure;
In particular, it is an object of the present invention to provide an orthogonal polarization demultiplexer having a novel configuration, which can reduce the axial length and has high cost performance characteristics.

[0005]

Means for Solving the Problems In order to achieve the above object, the orthogonal polarization splitter of the present invention has the following configuration. That is, the orthogonal polarization demultiplexer of the present invention is a waveguide type orthogonal polarization demultiplexer that combines or separates radio waves of two frequency bands that are orthogonally polarized and separated from each other; A dual-frequency main waveguide (rectangular waveguide or circular waveguide) that propagates while maintaining the orthogonal polarization relationship; A main waveguide that shares one end of the main waveguide and is perpendicular to the pipe axis of the main waveguide. a high frequency band waveguide section and a low frequency band waveguide section, which are arranged with their input and output ports facing in opposite directions on a straight line; The pipe portion forms a waveguide with an E-plane corner bent at 90° with respect to the main waveguide;
The low frequency band waveguide section is equipped with an impedance transformer for the low frequency band, and has a coupling window formed in the center of the outer corner side wall of the E-plane corner bent at 90 degrees. A waveguide with an H-plane corner bent at 90° is formed with respect to the main waveguide through the main waveguide.

[0006]

[Operation] Next, the operation of the orthogonal polarization splitter of the present invention constructed as described above will be explained. The orthogonal polarization splitter of the present invention forms a so-called composite T-shaped splitter in which a high frequency band waveguide section and a low frequency band waveguide section share one end of a main waveguide. There is. With this configuration, it is possible to determine the specifications of the two waveguide sections, including the coupling section with the main waveguide, which serve as cutoff regions for mutually orthogonal cross-polarized waves. It is possible to easily suppress interference between high-frequency radio waves and low-frequency radio waves, and has the advantage of excellent broadband characteristics. Furthermore, since the two waveguide sections intersect perpendicularly to the main waveguide, the length of the main waveguide in the tube axis direction can be compressed.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an orthogonal polarization splitter according to an embodiment of the present invention. In FIG. 1, 1 is a rectangular waveguide as a main waveguide. This rectangular waveguide 1 has two frequency bands separated from each other with orthogonal polarization relationships, with the lengths of the vertical and horizontal sides (a, b) being orthogonal to each other.
The conditions are met for transmitting only fundamental mode waves for radio waves (low frequency is Fl and high frequency is Fh). That is, the specifications of this rectangular waveguide 1 are (λh /2
)<a<λh and (λl/2)<a<λl. However, λh is the free space wavelength at the high frequency Fh, and λl is the free space wavelength at the low frequency Fh.
is the free space wavelength at l.

[0008] At one end of this rectangular waveguide 1, a waveguide section 2 for a high frequency band and a waveguide section 3 for a low frequency band are formed. Both of them share one end of the rectangular waveguide 1 and are arranged on a straight line perpendicular to the tube axis of the rectangular waveguide with their input and output ports facing oppositely. That is, the high frequency band waveguide section 2 connects one end of the rectangular waveguide 1 to a branch waveguide 5 (the tube axis of which is a rectangular waveguide) via a 45° corner wall 4 within the electric surface. (orthogonal to the tube axis of tube 1). The rectangular waveguide 1, the corner wall 4, and the branch waveguide 5 collectively form a waveguide with an E-plane corner bent at 90°. Also,
A coupling window 6 (c×l) is formed in the center of the corner wall 4, and the low frequency band waveguide section 3 has a tube axis that is similar to the tube axis of the rectangular waveguide 1. Branch waveguides 7 arranged orthogonally are matched and connected to one end of a rectangular waveguide 1 via an impedance transformer (1/4 wavelength transformer) 8 for low frequency band and a coupling window 6. It is. Rectangular waveguide 1 and coupling window 6 and 1/2
The wavelength transformer 8 and the branching waveguide 7 have an H-plane core as a whole.
It forms a waveguide with a 90° bend.

In the above configuration, the specifications of the coupling window 6 are as follows:
In order to suppress the coupling of the polarized wave of the high frequency Fh to the branching waveguide 7 for low frequency demultiplexing, a cutoff region (c<λh/2) is set for the polarized wave component. selected. In addition, the coupling windows 6 are arranged symmetrically within the electric surface of the high frequency Fh, and this coupling window 6 suppresses deterioration of cross-polarization discrimination at the same frequency due to disturbance of the electric field of the high frequency Fh. are doing. As a result, the coupling window 6 has no electrical influence on the high frequency Fh, so it is no different from a normal 90° bent waveguide.

On the other hand, h in the figure is the specification of the coupling window 9 for the high frequency Fh, which is determined so that h<λh/2, and the high frequency F1 is Range frequency F
The corner wall 4, which is the matching portion of h, becomes a cut-off region. Therefore, the coupling window 9 has almost no effect on the propagation of the low frequency Fl, and the radio wave of the low frequency Fl is branched into the branching waveguide 7 via the coupling window 6.

Note that since the coupling window 6 is opened only on one side wall, the electric field of the low frequency Fl is slightly shifted toward the coupling window side, but since it is arranged symmetrically within the electric surface,
Cross-polarized components are not excited. Therefore, it is possible to construct an orthogonal polarization splitter with a simple structure and excellent polarization separation for both frequencies (Fh, Fl). Furthermore, the branching waveguide 5 for high frequency Fh has its specifications g<λl/
2, it also serves as a cutoff filter for the low frequency Fl. However, the specification f is determined so as to satisfy the matching condition with the external connection device. Furthermore, in the branch waveguide 7 for low frequency Fl,
The specification c1 is c1 =√(c×d), but the other specifications (d, e) are determined so as to satisfy the matching condition with the external connection device.

In this embodiment, the main waveguide is constructed of a rectangular waveguide, but it is clear that it can be constructed of a circular waveguide in the same manner.

[0013]

Effects of the Invention As explained above, according to the orthogonal polarization splitter of the present invention, since the structure of a composite T-branch waveguide is basically adopted, the main waveguide is shared by two frequencies. This makes it possible to shorten the length of the antenna, making it possible to apply it to small antennas that have limitations in the antenna axis direction. Furthermore, since the high-frequency and low-frequency waveguide sections are arranged in a straight line orthogonal to the main waveguide, there is an effect that they can be used without interfering with each other in the arrangement of external devices.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of an orthogonal polarization splitter according to an embodiment of the present invention.

[Explanation of symbols]

1 Rectangular waveguide 2 Waveguide section for high frequency band 3 Waveguide section for low frequency band 4 Corner wall 5 Branch waveguide 6 Combined window 7 Branch waveguide 8 1/4 wavelength transformer 9 Combined window

Claims (1)

[Claims] [Claim 1] Two separated mutually having orthogonal polarization relationship.
In a waveguide type orthogonal polarization demultiplexer that combines or separates radio waves in frequency bands; A high-frequency waveguide that shares one end of the main waveguide and is arranged on a straight line orthogonal to the tube axis of the main waveguide with input and output ports facing oppositely to each other. A band waveguide section and a low frequency band waveguide section; The high frequency band waveguide section has a waveguide bent at an E-plane corner of 90 degrees with respect to the main waveguide. The low frequency band waveguide section is equipped with an impedance transformer for low frequency bands, and the E-plane corner is bent at 90° and the outer corner of the waveguide is formed.
An orthogonal polarization demultiplexer characterized in that a waveguide with an H-plane corner bent at 90 degrees is formed with respect to the main waveguide through a coupling window opened in the center of the inner side wall.