CN108598645B - Coupling structure from ridge waveguide to rectangular waveguide - Google Patents

Abstract

The invention belongs to the technical field of antennas, and particularly relates to a ridge waveguide-to-rectangular waveguide coupling structure, which comprises a ridge waveguide and a rectangular waveguide; the cavity of the ridge waveguide is communicated with the cavity of the rectangular waveguide through a coupling channel, and a transmission line penetrates through the middle of the ridge waveguide; the ridge waveguide is a single ridge waveguide, and two ends of the coupling channel are respectively connected with the top surface of the ridge waveguide and one end part of the rectangular waveguide; the coupling channel is an inclined H-shaped channel and comprises a linear gap I, a linear gap II and a connecting gap; two ends of the connecting gap are respectively connected with the middle points of the linear gap I and the linear gap II, and the linear gap I and the linear gap II are parallel to each other. The coupling structure has good flatness of the coupling coefficient and large adjustable range of the coupling coefficient, and meets the requirements of wide-angle scanning and low side lobe characteristics of a frequency scanning antenna.

Description

Coupling structure from ridge waveguide to rectangular waveguide

Technical Field

The invention belongs to the technical field of antennas, and particularly relates to a coupling structure from a ridge waveguide to a rectangular waveguide.

Background

The frequency scanning antenna has the advantages of high gain, low sidelobe, wide-angle scanning, low cost, simple structure and the like, and is widely applied to low-altitude search radars and ground warning radars in recent years, a frequency scanning antenna feed network generally adopts a slow wave line and coupling feed structure, the slow wave line has the characteristics of low requirement on loss, high reliability and the like, the generally commonly used slow wave lines comprise waveguide slow wave lines and strip line slow wave lines, and the ridge waveguide to rectangular waveguide coupling feed structure can be applied to ridge waveguide slow wave lines.

Compared with the rectangular waveguide, the ridge waveguide has the advantages of wide bandwidth, low impedance, small size and the like, and can replace the rectangular waveguide to complete the distribution of the feed network in places where the rectangular waveguide is difficult to arrange. In order to meet the wide-angle scanning and low side lobe characteristics of a frequency scanning antenna, the slow wave line coupling feed structure is required to have the advantages of large adjustable coupling degree range, broadband operation, good coupling coefficient flatness and the like. On the premise that certain space is limited, the slow wave line coupling feed structure needs to adopt a ridge waveguide to rectangular waveguide form, the common ridge waveguide to rectangular waveguide coupling feed structure is an inclined gap coupling feed structure, and the structure has the problems of poor coupling coefficient flatness, narrow coupling range and the like, and cannot meet the performance index requirement under the broadband working condition.

Disclosure of Invention

According to the problems in the prior art, the invention provides a coupling structure from a ridge waveguide to a rectangular waveguide, the coupling structure has good flatness of a coupling coefficient and a large adjustable range of the coupling coefficient, and the wide-angle scanning and low side lobe characteristics of a frequency scanning antenna are met.

The invention adopts the following technical scheme:

a ridge waveguide-to-rectangular waveguide coupling structure comprises a ridge waveguide and a rectangular waveguide; the cavity of the ridge waveguide is communicated with the cavity of the rectangular waveguide through a coupling channel, and a transmission line penetrates through the middle of the ridge waveguide.

Preferably, the ridge waveguide is a single ridge waveguide, and two ends of the coupling channel are respectively connected with the top surface of the ridge waveguide and one end of the rectangular waveguide.

Further preferably, the coupling channel is an inclined H-shaped channel, which includes a linear gap i, a linear gap ii and a connecting gap; two ends of the connecting gap are respectively connected with the middle points of the linear gap I and the linear gap II, and the linear gap I and the linear gap II are parallel to each other;

more preferably, in the coupling channel, the length of the straight-line-shaped gap i and the straight-line-shaped gap ii is L1, and the length of the connecting gap is L2; the included angle between the linear gaps I and II and the width direction of the ridge waveguide is alpha, and the included angle between the connecting gaps and the width direction of the ridge waveguide is beta; the middle point of the linear gap I is a point D, the two end points are a point F and a point H, the middle point of the linear gap II is a point E, and the two end points are a point G and a point I; the length L1, the length L2, the included angle alpha and the included angle beta are all adjustable.

The invention has the beneficial effects that:

1) in the coupling structure, the cavity of the ridge waveguide is communicated with the cavity of the rectangular waveguide through the inclined H-shaped coupling channel; the coupling channel comprises a linear gap I, a linear gap II and a connecting gap; two ends of the connecting gap are respectively connected with the middle points of the linear gap I and the linear gap II, and the linear gap I and the linear gap II are parallel to each other. In the coupling channel, the length of the linear gap I and the linear gap II is L1, and the length of the connecting gap is L2; the included angle between the linear gaps I and II and the width direction of the ridge waveguide is alpha, and the included angle between the connecting gaps and the width direction of the ridge waveguide is beta; the middle point of the linear gap I is a point D, the two end points are a point F and a point H, the middle point of the linear gap II is a point E, and the two end points are a point G and a point I.

The coupling channel is provided with two resonance paths, namely a path FDEG and a path HDEI, the length of the edge of a gap where the path FDEG is located represents the low-frequency resonance length of the coupling channel, the length of the edge of the gap where the path HDEI is located represents the high-frequency resonance length of the coupling channel, and the larger the difference between the low-frequency resonance length and the high-frequency resonance length, the wider the resonance bandwidth; the structure of the coupling channel expands the difference between the low-frequency resonance length and the high-frequency resonance length, and also expands the range of a resonance path, thereby realizing the design of the coupling degree with stable broadband characteristics and expanding the adjustment range of the coupling coefficient.

Drawings

Fig. 1 is a perspective view of a coupling structure of the present invention.

Fig. 2a is a top view of the coupling structure of the present invention.

Fig. 2b is a top view of the coupling structure of the present invention with the rectangular waveguide removed.

Fig. 3 is a side view of the coupling structure of the present invention.

Fig. 4 is a first labeled diagram of a coupling channel of the coupling structure of the present invention.

FIG. 5a is a second labeled diagram of a coupling channel of the coupling structure of the present invention.

FIG. 5b is a third illustration of a coupling channel of the coupling structure of the present invention.

Fig. 6 is a graph of the S11 reflection coefficient of a coupling structure in an embodiment of the invention.

Fig. 7 is a diagram of S12 transmission coefficients of a coupling structure in an embodiment of the invention.

Fig. 8 is a graph of the S13 coupling coefficients of the coupling structure in an embodiment of the invention.

Reference numerals: 1-ridge waveguide, 2-rectangular waveguide, 3-coupling channel, 31-linear slot i, 32-linear slot ii, 33-connecting slot.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 and fig. 2a, a ridge waveguide-to-rectangular waveguide coupling structure includes aridge waveguide 1 and arectangular waveguide 2; the cavity of theridge waveguide 1 is communicated with the cavity of therectangular waveguide 2 through acoupling channel 3, and a transmission line penetrates through the middle of theridge waveguide 1.

Theridge waveguide 1 is a single ridge waveguide, and two ends of thecoupling channel 3 are respectively connected with the top surface of theridge waveguide 1 and one end of therectangular waveguide 2.

As shown in fig. 2b, thecoupling channel 3 is an inclined H-shaped channel, which includes alinear slit i 31, a linear slit ii 32 and a connectingslit 33; two ends of the connectinggap 33 are respectively connected with the middle points of the I31 and the II 32 linear gaps, and the I31 and the II 32 linear gaps are parallel to each other.

As shown in fig. 4, in thecoupling channel 3, the length of the linear slot i 31 and the linear slot ii 32 is L1, and the length of theconnecting slot 33 is L2; the included angle between the linear gap I31 and the linear gap II 32 and the width direction of theridge waveguide 1 is alpha, and the included angle between the connectinggap 33 and the width direction of theridge waveguide 1 is beta; the middle point of the linear gap I31 is a point D, the two end points are a point F and a point H, the middle point of the linear gap II 32 is a point E, and the two end points are a point G and a point I;

thecoupling channel 3 is provided with two resonance paths, namely a path FDEG and a path HDEI, the length of the gap edge where the path FDEG is located represents the low-frequency resonance length of thecoupling channel 3, the length of the gap edge where the path HDEI is located represents the high-frequency resonance length of thecoupling channel 3, and the larger the difference between the low-frequency resonance length and the high-frequency resonance length, the wider the resonance bandwidth; the coupling degree design in a large range is realized by adjusting the length L1, the length L2, the included angle alpha and the included angle beta.

The coupling structure in the present invention will be illustrated with reference to the following embodiments.

Example 1:

the working frequency band of the coupling structure of the embodiment is 15 GHz-20 GHz, and the coupling degree is-11 dB. As shown in fig. 1, fig. 1 is a perspective view of a coupling feed structure from a ridge waveguide to a rectangular waveguide according to the present invention, where a direction shown at a is a signal input port direction, a direction shown at B is a signal through port direction, and a direction shown at C is a coupling signal output port direction.

As shown in fig. 2a and 3, theridge waveguide 1 is a single ridge waveguide, and has a ridge width Td of 1.5mm, a narrow side Th of 5mm, a side width Tw of 1.5mm, and a ridge depth Tb of 4.2 mm. The narrow side Ta of therectangular waveguide 2 is 4.5mm, the wide side Tk is 12.95mm, and the depth dd of the coupling channel is 0.8 mm.

As shown in fig. 4, point D is a central point of the linear slot I31, point E is a central point of the linear slot ii 32, point F and point G are respectively located at two sides of the connection line DE, point H and point I are respectively located at two sides of the connection line DE, the path FDEG and the path HDEI are both "Z", the coupling channel has two resonant paths FDEG and HDEI, where FD ═ EG ═ HD ═ EI ═ 3.9mm and DE ═ 4.6mm, an angle α between the linear slot I31 and the linear slot ii 32 and the width direction of theridge waveguide 1 is 69.3 °, and an angle β between theconnection slot 33 and the width direction of theridge waveguide 1 is 71.7 °.

The following simulation shows that the coupling structure of the present embodiment satisfies the operation performance of the antenna.

As shown in fig. 6, fig. 6 is a S11 reflection coefficient diagram of the coupling structure of the present embodiment. As can be seen from FIG. 6, the index of the reflection coefficient S11 in the bandwidth of the working frequency of 15-20 GHz is better than-20 dB, and the working performance requirement of the scanning antenna is met.

As shown in fig. 7, fig. 7 is a S12 transmission coefficient diagram of the coupling structure of the present embodiment. As can be seen from fig. 7, the transmission coefficient S12 fluctuates by about 0.1dB in the bandwidth within the operating frequency of 15 to 20GHz, and the fluctuation is small, so that the requirement of the working performance of the scanning antenna is satisfied.

As shown in fig. 8, fig. 8 is a diagram of the S13 coupling coefficient of the coupling structure of the present embodiment. As can be seen from FIG. 8, the coupling fluctuation in the working frequency of 15-20 GHz is from-10.82 dB to-11.55 dB, the fluctuation is very small, the coupling coefficient flatness is good, and the working performance requirement of the scanning antenna is met.

As shown in fig. 5a and 5b, point F and point G are respectively located at two sides of connection line DE, point H and point I are respectively located at two sides of connection line DE, path FDEG and path HDEI are both in a "Z" shape, the length of the gap edge where path FDEG is located represents the low-frequency resonance length ofcoupling channel 3, the length of the gap edge where path HDEI is located represents the high-frequency resonance length ofcoupling channel 3, and the difference between the low-frequency resonance length and the high-frequency resonance length corresponds to the adjustment range of coupling coefficient; therefore, the coupling structure in this embodiment can increase the difference between the low-frequency resonance length and the high-frequency resonance length by adjusting the length L1, the length L2, the included angle α, and the included angle β, and increase the adjustment range of the coupling coefficient.

In conclusion, the coupling structure has good flatness of the coupling coefficient and a large adjustable range of the coupling coefficient, and meets the requirements of wide-angle scanning and low side lobe characteristics of a frequency scanning antenna.

Claims (2)

1. A ridge waveguide to rectangular waveguide coupling structure, characterized by: comprises a ridge waveguide (1) and a rectangular waveguide (2); the cavity of the ridge waveguide (1) is communicated with the cavity of the rectangular waveguide (2) through a coupling channel (3);

the ridge waveguide (1) is a single ridge waveguide, and two ends of the coupling channel (3) are respectively connected with the top surface of the ridge waveguide (1) and one end part of the rectangular waveguide (2);

the coupling channel (3) is an inclined H-shaped channel and comprises a linear gap I (31), a linear gap II (32) and a connecting gap (33); two ends of the connecting gap (33) are respectively connected with the middle points of the straight-line-shaped gap I (31) and the straight-line-shaped gap II (32), and the straight-line-shaped gap I (31) is parallel to the straight-line-shaped gap II (32).

2. The ridge waveguide-to-rectangular waveguide coupling structure of claim 1, wherein: in the coupling channel (3), the length of the linear gap I (31) and the linear gap II (32) is L1, and the length of the connecting gap (33) is L2; the included angle between the linear gap I (31) and the linear gap II (32) and the width direction of the ridge waveguide (1) is alpha, and the included angle between the connecting gap (33) and the width direction of the ridge waveguide (1) is beta; the middle point of the linear gap I (31) is a point D, the two end points are a point F and a point H, the middle point of the linear gap II (32) is a point E, and the two end points are a point G and a point I; the length L1, the length L2, the included angle alpha and the included angle beta are all adjustable.

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