CN201540963U - A Feedback Millimeter-Wave Broadband Double-ridge Horn Antenna - Google Patents

Abstract

A rear-fed millimeter wave broad band double-ridged horn antenna belongs to the technical field of micro-wave millimeter wave signal processing, and relates to a millimeter wave broad band double-ridged horn antenna, which comprises a coaxial line inspiring portion, a ridge wave guide portion and a double-ridge horn portion. The coaxial line inspiring portion is formed by sequentially connecting a coaxial line, a module changing portion and an impedance matching portion; the module changing portion is formed by connecting a shield panel line with a back ridge and a back ridge square coaxial line; the impedance matching portion is stepped gradual double-ridge wave guide; the ridge wave guide portion is standard double-ridge wave guide; and two ridges of the double-ridge horn portion are formed by extending two ridges of the ridge wave guide portion outwards to a horn opening. The antenna adopts a rear-fed structure, electromagnetic wave is fed from the direction parallel to the ridge wave guide transmitting direction from the rear portion of ridge wave guide, the coaxial line is positioned on the same axis with the wave guide, and comparatively small voltage standing-wave ratio can be obtained. By mode changing and impedance matching, satisfied property can be obtained within 18-40 GHz broad band range. The rear-fed millimeter wave broad band double-ridged horn antenna has the advantages of broad frequency band, compact structure and excellent performance.

Description

A Feedback Millimeter-Wave Broadband Double-ridge Horn Antenna

technical field

The utility model belongs to the technical field of microwave and millimeter wave signal processing, and relates to a millimeter wave antenna, in particular to a millimeter wave broadband horn antenna.

Background technique

With the development of millimeter-wave technology, its role in aerospace, meteorological communication and modern military systems is becoming more and more important. Horn antennas are widely used in this field due to their large power capacity, wide frequency band, high gain and good directivity. The application and development, usually used as an independent antenna and feed. In order to extend the working frequency band of the antenna, it is necessary to add ridges to the horn antenna.

The millimeter-wave double-ridge horn antenna widely used at present (as shown in Figure 1) is an in-line double-ridge horn antenna. The coaxial feeding probes are inserted perpendicular to the E-plane of the waveguide, and the λ/ Add short-circuit boards at 4 places to form a rear cavity. The design idea of this structure is to regard the coaxial probe as a transmitting antenna to excite the electromagnetic field in the waveguide. Since one end of the waveguide is short-circuited, the energy can only propagate in one direction. By analyzing the current distribution on the probe, its input impedance is calculated, and then matched according to its characteristic impedance. In order to be able to match better, the probe head should have a gradual change, but when the shape of the probe is irregular, the surface current distribution cannot be obtained accurately, so the theoretical analysis and calculation are difficult, resulting in the inability to carry out accurate and effective design, making the manufactured The performance of the coaxial feed part is poor, and the input standing wave is relatively large, especially in the case of millimeter wave and wide frequency band. In addition, because the coaxial connector and the waveguide form an angle of 90 degrees, it is inconvenient to connect in some cascaded systems, and when the transmission power is large, the top of the probe is prone to breakdown.

Contents of the invention

The purpose of this invention is to provide a feed-back millimeter-wave broadband double-ridge horn antenna. The antenna adopts a feed-back structure, and its coaxial line is on the same axis as the waveguide. It is analyzed and designed with the ideas of mode conversion and impedance matching. Satisfactory characteristics can be obtained in a wide band. The antenna has the characteristics of wide frequency band, compact structure and good performance.

The technical scheme of the utility model is as follows:

A feed-back millimeter-wave broadband double-ridge horn antenna, as shown in FIG. The excitation part of the coaxial line is composed of a coaxial line 11, a mode conversion part 12 and an impedance matching part 13, which are sequentially fixedly connected; 122 connected; the middle of the lower metal plate of the ridged shielded flat line 121 is provided with a groove (i.e. a ridge) along the axial direction, and one end is closed with a metal short circuit board; a coupling hole is opened on the metal short circuit board, The diameter of the coupling hole is the same as the inner diameter of the outer conductor of the coaxial line 11 . A groove (that is, a ridge) is formed in the middle of the lower metal plate coaxial with the ridge 122 along the axial direction. The impedance matching part 13 is a section of double ridge waveguide with stepped ridges. The ridge waveguide part 2 is a standard double ridge waveguide. The two ridges 31 of the double-ridge horn part 3 extend outward from the two ridges of the ridge waveguide part 2 to the horn mouth.

The outer conductor of the coaxial line 11 is fixed on the metal short circuit board of the shielded flat line 121, and the outer conductor of the coaxial line 11 is concentric with the coupling hole on the metal short circuit board of the shielded flat line 121; The inner conductor and the inner conductor of the shielded flat line 121 with ridges adopt the same material to be made into the same shape, form a whole, and be connected with the inner conductor of the ridge side coaxial line 122; the shielded flat line 121 and the ridged side coaxial line The shielding metal plate 122 is made of the same material and has the same shape to form a whole; the ridges of the shielding flat line 121 and the ridge coaxial line 122 are the same.

In the above solution, the two ridges of the double-ridged horn part 3 may be ridges with an exponential curve gradient, or ridges with a multi-segment linear gradient. In order to increase the firmness of the connection between the inner conductor of the ridged shielded flat line 121 and the inner conductor of the ridged coaxial line 122, holes can be made on the inner conductor of the ridged coaxial line 122, and the ridged shielded flat line The inner conductor of 121 is inserted in the opening of the inner conductor of the ridge side coaxial line 122, and sticks firmly with conductive glue. The step-shaped gradual ridge of the impedance matching part 13 calculates the required number of sections and the characteristic impedance of each section according to the Chebyshev impedance matching formula, and then determines the size of each section.

The working principle of the feed-back millimeter-wave broadband double-ridge horn antenna provided by the utility model is as follows:

Electromagnetic waves are fed through the coaxial line 11 through the coupling hole from the back of the ridge waveguide parallel to the transmission direction of the ridge waveguide, and first enter the mode conversion part 12 . From a structural point of view, the mode conversion part is further divided into two different structural areas, firstly a section of shielded flat line 121 with ridges, and then a section of ridged square coaxial lines 122 . These two structures are TEM wave transmission lines, which can better perform mode conversion, so that the electromagnetic field energy can be more matched from the coaxial line to the ridge waveguide. The coaxial line is a TEM wave, and the electric field is symmetrical about the Ф direction, and is evenly distributed in the coaxial line. When passing through the shielded flat line with a ridge, the electric field energy is concentrated between the inner conductor and the upper and lower metal plates, and enters the ridged side of the coaxial line. After the line, due to the large space of the ridge below, the energy of the electromagnetic field is scattered, so the energy of the electric field is further concentrated between the inner conductor and the upper plate. In this way, the main electric field energy can gradually transition from the coaxial line to between the two ridges of the ridge waveguide portion 2 . The purpose of the slots (that is, the added ridges) under these two parts is to reduce the capacitance of the lower part, so that the electric field is concentrated on the upper part, so as to achieve the purpose of smooth transition of electromagnetic waves, and at the same time, it can also reduce the requirements for machining accuracy. .

The impedance matching part adopts multi-section quarter-wavelength step impedance transformation, and the impedance gradually decreases as the height of the ridge increases. In this way, the standard ridge waveguide is transformed into a low-impedance ridge waveguide through the stepwise transformation of the ridge waveguide, which matches the 50 ohm characteristic impedance of the coaxial line and the mode conversion part to obtain a satisfactory VSWR.

The beneficial effects of the utility model are: the antenna adopts a back-feed structure, the electromagnetic wave is fed from the back of the ridge waveguide parallel to the transmission direction of the ridge waveguide, and the coaxial line 11 is on the same axis as the waveguide, so that a smaller voltage standing wave can be obtained Ratio; Using the idea of mode conversion and impedance matching for analysis and design, satisfactory characteristics can be obtained in the broadband range of 18-40GHz, and it has the characteristics of wide frequency band, compact structure and good performance.

Description of drawings:

FIG. 1 is a schematic cross-sectional view of an existing in-line double-ridge horn antenna.

Fig. 2 is a three-dimensional schematic diagram of the feed-back millimeter-wave broadband double-ridge horn antenna provided by the utility model.

Fig. 3 is a schematic cross-sectional view of the feed-back millimeter-wave broadband double-ridge horn antenna provided by the utility model.

FIG. 4 is a schematic cross-sectional view of the ridged shielded flat wire 121 in the feed-back millimeter-wave broadband double-ridged horn antenna provided by the present invention.

FIG. 5 is a schematic cross-sectional view of the ridge-square coaxial line 122 in the feed-back millimeter-wave broadband double-ridge horn antenna provided by the present invention.

Detailed ways

A feed-back millimeter-wave broadband double-ridge horn antenna, as shown in FIG. 3 , includes three parts: a coaxial line excitation part 1 , which includes a coaxial line 11 , a mode conversion part 12 and an impedance matching part 13 . The coaxial joint of the coaxial line 11 can be a 2.4 type or a 2.92 type coaxial joint, and its inner conductor is inserted into the inner conductor of the ridge side coaxial line 122 through the coupling hole, and glued firmly with conductive glue. The total length of the mode conversion part 12 is a quarter wavelength of the center frequency, and is divided into two parts: the former part is a shielded flat line 121 with a ridge, and the latter part is a ridged coaxial line 122, both of which are The TEM wave transmission line structure is designed with a characteristic impedance of 50Ω, and a rectangular groove, namely the ridge 123, is opened on the metal wall below the mode conversion part. The step impedance matching part 13 is a section of double ridge waveguide with step-shaped gradual ridges. Different characteristic impedances are obtained by changing the ridge height of the ridge waveguide for impedance matching. The length of each section is a quarter wavelength of the center frequency.

The ridge waveguide part 2 is a standard 180 double ridge waveguide.

The two ridges 31 of the double-ridge horn part 3 extend outward from the two ridges of the ridge waveguide part 2 to the horn mouth. The two ridges of the double-ridged horn part 3 may be ridges with an exponential curve gradient, or ridges with a multi-segment linear gradient.

If the two ridges of the double-ridge horn part 3 are ridges with an exponential curve gradient, relatively good gain and directivity can be achieved in a wide band. However, in the actual engineering design process, the exponential curve will bring a huge amount of calculation to the computer simulation. Simulations take longer and optimizations are more difficult to achieve. Moreover, the processing of the exponential curve is difficult, it is difficult to guarantee the accuracy, the processing consistency is poor, and the yield is low.

If the two ridges of the double-ridge horn part 3 are multi-segment linear gradation ridges, the processing accuracy requirements and processing costs can be reduced, the processing is more convenient, the consistency can be guaranteed, and the yield is high. In the actual design, first draw the extended ridge curve according to the form of the exponential curve, take every 1/4 wavelength of the center frequency as a section in the radiation direction, obtain the connection points with the exponential curve, and then connect each connection point with a linear line segment, This constitutes a multi-segment linear gradient extension ridge.

The simulation results of the feed-back millimeter-wave broadband double-ridge horn antenna provided by the utility model show that: 1. The operating frequency of the antenna can reach 18-40 GHz, and the relative bandwidth can reach 75.9%; 2. The standing wave at the input end is small, and the power utilization The rate is higher.

Claims (4)

1. a back-fed millimeter wave broadband double ridged horn antenna comprises coaxial line excited part (1), ridge waveguide part (2) and two ridged horn parts (3); Described coaxial line excited part is formed by connecting by coaxial line (11), mode converting part (12) and impedance matching part (13) fixed order;

It is characterized in that:

Described mode converting part (12) is formed by connecting by one section shield plate line (121) and one section ridge square coaxial line (122) that adds ridge; Have groove along axis direction in the middle of the following metallic plate of the described shield plate line (121) that adds ridge, i.e. ridge (123), an end adopts the sealing of short circuit metal plate; Have a coupling aperture on the described short circuit metal plate, the aperture of coupling aperture is identical with the internal diameter of the outer conductor of coaxial line (11); Have groove along axis direction in the middle of the following metallic plate of described ridge square coaxial line (122), i.e. ridge (123); Described impedance matching part (13) is one section double ridged waveguide with stairstepping gradual change ridge; Described ridge waveguide part (2) is the double ridged waveguide of a segment standard; Two ridges (31) of described pair of ridged horn part (3) extend out to horn mouth by two ridges of ridge waveguide part (2);

The outer conductor of described coaxial line (11) is fixed on the short circuit metal plate of shield plate line (121), and the coupling aperture on the short circuit metal plate of the outer conductor that guarantees coaxial line (11) and shield plate line (121) is concentric; The inner wire of coaxial line (11) adopts identical materials to make identical shape with the inner wire of the shield plate line (121) that adds ridge, forms an integral body, and links to each other with the inner wire of ridge square coaxial line (122); The shielded metal plate of shield plate line (121) and ridge square coaxial line (122) adopts identical materials to make identical shape, forms an integral body; Shield plate line (121) is identical with the ridge of ridge square coaxial line (122).

2. back-fed millimeter wave broadband double ridged horn antenna according to claim 1 is characterized in that, two ridges of described pair of ridged horn part (3) are the ridges that is the exponential curve gradual change.

3. back-fed millimeter wave broadband double ridged horn antenna according to claim 1 is characterized in that, two ridges of described pair of ridged horn part (3) are the ridges that is the multistage linear gradient.

4. according to claim 1,2 or 3 described back-fed millimeter wave broadband double ridged horn antennas, it is characterized in that, has perforate on the inner wire of described ridge square coaxial line (122), the inner wire of the described shield plate line (121) that adds ridge inserts in the perforate of inner wire of ridge square coaxial line (122), and cements with conducting resinl.

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