A millimeter-wave terahertz circular polarizer with a planar phase-shifting structure

Abstract

The present invention discloses a millimeter wave terahertz circular polarizer with a planar phase-shifting structure, which belongs to the field of microwave antenna technology. The circular polarizer is provided with at least two groups of protruding structures on the inner wall of a circular waveguide, and each group of protruding structures includes two protruding platforms that are directly opposite and mirror-symmetrical; each group of protruding structures has an angle in the circumferential direction of the circular waveguide; a transition is provided between the top surface of the protruding platform and the inner wall of the circular waveguide; and each group of protruding structures does not overlap in the axial direction of the circular waveguide. The present invention has the characteristics of simple structure, can be integrally processed and formed, and is easy to process in the millimeter wave terahertz band.

Description

Technical Field

[0001] The invention relates to the technical field of microwave antennas, and in particular to a millimeter-wave terahertz circular polarizer with a planar phase-shift structure. Background Art

[0002] With the development of modern society and radio communication technology, frequency band resources are becoming more and more valuable. Research and development of new frequency band applications are imminent. Millimeter wave and terahertz have received widespread attention. The most advanced equipment of all wireless communication systems, antennas, have become one of the main research objects of millimeter wave and terahertz technology. The function of the antenna is to transmit and receive signals, and its performance is directly related to the performance of the entire antenna system. In some special fields such as satellite communications, radio astronomy, and electronic countermeasures, linear polarization often cannot meet the requirements of the communication system, while circularly polarized antennas have the characteristics of anti-rain and fog interference, receiving and transmitting waves of arbitrary polarization, etc., so they are widely used.

[0003] With the rapid development of the communication industry, especially in the satellite communication industry, various forms of circularly polarized antennas are widely used to meet the development needs of communication systems. Waveguide circular polarizers are microwave devices that can generate circularly polarized signals. Compared with microstrip circular polarizers, waveguide circular polarizers have the advantages of low loss and high power capacity under high power conditions. They can well adapt to the needs of antenna systems. Therefore, they are increasingly favored by scientific researchers and engineering designers. Various forms of circular polarizers have been designed and widely used in satellite communications, electronic countermeasures, radar, radio astronomy and other communication fields.

[0004] In the communication fields such as satellite communication and radio astronomy, circularly polarized reflector antennas, mainly in the form of parabolic antennas in ground base stations, are widely used. As an important component of the antenna feed system, the circular polarizer converts the linear polarization signal into a circular polarization signal in a certain way, or separates the received circular polarization signal into a linear polarization signal in a certain way. Therefore, designing a circular polarizer with excellent performance is crucial to improving the performance of the entire antenna system.

[0005] Common waveguide circular polarizer types include screw adjustment type, dielectric insert type, corrugated type, partition type and ridge waveguide type. However, due to the high frequency of millimeter wave and terahertz frequency bands, theoretical research and actual processing measurements need to be considered together. At the same time, the processing technology of millimeter wave and terahertz passive waveguide devices also greatly limits the specific physical molding, and the above-mentioned types of waveguide circular polarizers have the problems of difficult processing, difficult to guarantee the processing difficulty, and large differences between the test after processing and theoretical calculation. Summary of the invention

[0006] In view of this, the present invention provides a millimeter-wave terahertz circular polarizer with a planar phase-shifting structure; the millimeter-wave terahertz circular polarizer has the characteristics of simple structure, can be integrally processed and formed, and is easy to process in the millimeter-wave terahertz band.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A millimeter-wave terahertz circular polarizer with a planar phase-shift structure comprises a circular waveguide and a first flange and a second flange located at both ends of the circular waveguide. At least two groups of protrusion structures are arranged on the inner wall of the circular waveguide, and each group of protrusion structures comprises two protrusion platforms that are directly opposite and mirror-symmetrical. Each group of protrusion structures has an angle in the circumferential direction of the circular waveguide. A transition is arranged between the top surface of the protrusion platform and the inner wall of the circular waveguide. In the axial direction of the circular waveguide, each group of protrusion structures does not overlap.

[0009] Furthermore, the transition is a step structure or a smooth curved surface.

[0010] The beneficial effects of the above technical solution of the present invention are:

[0011] 1. The structure of the present invention is relatively simple compared with the traditional form, does not contain any phase shifting unit with a small structural size, and realizes circular polarization only by changing the shape of the circular waveguide wall. It can be processed and formed in one piece and is suitable for mass production.

[0012] 2. The circular polarization function of the present invention is realized mainly by adjusting the length of the raised platform, the distance from the raised platform to the axis of the circular waveguide, and the angle between each group of raised structures. It does not contain a phase shifting unit with a tiny structure, which overcomes the shortcomings of the existing circular polarizer that is difficult to process in the millimeter wave and terahertz bands. It has the advantages of simple structure, excellent electrical performance, and can be applied to the millimeter wave and terahertz bands. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0014] Figure 2 yes Figure 1 Side view of.

[0015] Figure 3 yes Figure 2 Mid-section AA view.

[0016] Figure 4 yes Figure 2 Mid-section BB view.

[0017] Figure 5 yes Figure 2 Mid-section CC view.

[0018] Figure 6 yes Figure 2 Mid-section DD view

[0019] Figure 7 is the reflection loss of the vertically polarized wave in the embodiment of the present invention.

[0020] Figure 8 is the reflection loss of the horizontally polarized wave in the embodiment of the present invention.

[0021] Fig. 9 is the transmission phase difference of the two polarized waves in the embodiment of the present invention.

[0022] Fig.10 is the circular polarization axial ratio of the embodiment of the present invention.

[0023] In the figure: 1, circular waveguide, 2-1, first raised platform, 2-2, second raised platform, 3-1, third raised platform, 3-2, fourth raised platform, 4, transition from first raised structure to circular waveguide wall, 5, transition from second raised structure to circular waveguide wall, 6-1, first flange, 6-2, second flange. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] A millimeter-wave terahertz circular polarizer with a planar phase-shift structure comprises a circular waveguide and a first flange and a second flange located at both ends of the circular waveguide. At least two groups of protrusion structures are arranged on the inner wall of the circular waveguide, and each group of protrusion structures comprises two protrusion platforms that are directly opposite and mirror-symmetrical. Each group of protrusion structures has an angle in the circumferential direction of the circular waveguide. A transition is arranged between the top surface of the protrusion platform and the inner wall of the circular waveguide. In the axial direction of the circular waveguide, each group of protrusion structures does not overlap.

[0026] Furthermore, the transition is a step structure or a smooth curved surface.

[0027] The following is a more specific embodiment:

[0028] See also Figures 1 to 6 This embodiment includes a circular waveguide 1, a first raised platform 2-1, a second raised platform 2-2, a third raised platform 3-1, a fourth raised platform 3-2, a transition 4 from the first raised platform 2-1 and the second raised platform 2-2 to the circular waveguide wall, a transition 5 from the third raised platform 3-1 and the fourth raised platform 3-2 to the circular waveguide wall, a first flange 6-1 and a second flange 6-2.

[0029] The first, second, third and fourth raised platforms are arranged at specific positions of the circular waveguide wall.

[0030] The first and second raised platforms are opposite to and mirror-symmetrical to the first raised structure, the third and fourth raised platforms are opposite to and mirror-symmetrical to the second raised structure, there is an angle between the first raised structure and the second raised structure, and the transformation between the first, second, third, and fourth raised platforms and the circular waveguide wall is achieved by gradual transition.

[0031] The lengths of the first and second raised platforms and the third and fourth raised platforms may be the same or different.

[0032] The lengths of the first and second raised platforms and the third and fourth raised platforms are generally greater than 0.25λ (λ is the free space wavelength of the center frequency) to ensure that there is enough phase shift between the two orthogonal polarized waves.

[0033] The distances between the first and second raised platforms and the third and fourth raised platforms and the axis of the circular waveguide can be the same or different.

[0034] The distance between the first and second raised platforms and the third and fourth raised platforms and the axis of the circular waveguide is generally greater than 3 / 4 of the radius of the circular waveguide, so as to facilitate the transition from the plane to the circular waveguide wall with good matching performance.

[0035] The angle between the first and second raised platforms and the third and fourth raised platforms can be any value according to the design, and the angle is generally obtained by optimization design.

[0036] The transformation between the first, second, third and fourth raised platforms and the circular waveguide wall is achieved by gradual transition, and the transition can be a straight line or a curve, with the design goal of achieving good impedance matching.

[0037] The distances between the first and second raised platforms and the third and fourth raised platforms can be any values ​​according to the design and are obtained through optimization.

[0038] The circular waveguide can transmit the working frequency well, and the selection of the circular waveguide aperture is based on the principle that the working frequency is more than 1.1 times the cut-off frequency of the circular waveguide.

[0039] The flanges are located at both ends of the circular waveguide and are used for connecting with other components.

[0040] Its electrical transmission performance was verified as follows:

[0041] Figure 7 The reflection loss of the vertically polarized wave within the frequency band is given. It can be seen that within the designed bandwidth, the vertical polarization reflection loss is <-25dB.

[0042] Figure 8 The reflection loss of horizontal polarization within the frequency band is given. It can be seen that within the designed bandwidth, the reflection loss of horizontal polarization is <-24dB.

[0043] Fig. 9 The phase difference between two orthogonally polarized waves within the frequency band is given. It can be seen that within the designed bandwidth, the phase difference satisfies 90°±8°.

[0044] Fig.10 The corresponding circular polarization axial ratio within the frequency band is given, and it can be seen that within the designed bandwidth, the axial ratio is <1dB.

[0045] It can be seen from the results that compared with the prior art, this embodiment has a very simple structure, excellent performance, can be integrally processed and formed, and is suitable for millimeter wave and terahertz applications.

[0046] The brief working principle of the embodiment of the present invention is as follows:

[0047] A linear polarized wave can be decomposed into two linear polarized waves of equal amplitude and same phase; a circular polarized wave can be decomposed into two linear polarized waves of equal amplitude and 90° phase difference. The working principle of the present invention is as follows: when two linear polarized waves of equal amplitude and same phase are input from the circular waveguide port of the circular polarizer, the propagation constants of the two linear polarized waves in the circular waveguide are made different by changing the shape of the circular waveguide wall, and by adjusting the length of the first, second, third, and fourth raised platforms, the distance between the first, second raised platforms and the third, fourth raised platforms and the axis of the circular waveguide, and the angle between the first, second raised platforms and the third, fourth raised platforms, the two polarized waves have equal amplitudes and a phase difference of 90° after passing through the circular polarizer, thereby forming circular polarization.

Claims

1. A millimeter-wave terahertz circular polarizer with a planar phase-shift structure, comprising a circular waveguide and a first flange and a second flange located at both ends of the circular waveguide, characterized in that: At least two groups of protrusion structures are provided on the inner wall of the circular waveguide, each group of protrusion structures includes two protrusion platforms that are directly opposite and mirror-symmetrical; each group of protrusion structures has an angle in the circumferential direction of the circular waveguide; a transition is provided between the top surface of the protrusion platform and the inner wall of the circular waveguide; in the axial direction of the circular waveguide, each group of protrusion structures does not overlap; The transition is a step structure or a smooth curved surface; The length of the raised platform is greater than 0.25λ, λ is the free space wavelength of the center frequency, and the distance between the raised platform and the axis of the circular waveguide is greater than 3 / 4 of the radius of the circular waveguide.

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