Air coupling dual-polarization combined radar antenna and transmitting and receiving method thereof

Abstract

The invention relates to an air coupling dual-polarization combined radar antenna and a transceiving method thereof, belongs to the technical field of ground penetrating radar antennas, and solves the problems of low gain and poor air coupling detection effect of a radar antenna in the prior art. According to the invention, four same antenna units are orthogonally combined to form the dual-polarized combined antenna with two transmitting and two receiving; the four antenna units comprise a first transmitting antenna, a first receiving antenna, a second transmitting antenna and a second receiving antenna; the first transmitting antenna and the first receiving antenna are bilaterally symmetrical; and the second transmitting antenna and the second receiving antenna are vertically symmetrical. The radar antenna provided by the invention adopts an air coupling system, is stronger in directivity and higher in efficiency, can couple more energy into a to-be-detected target body, is suitable for air coupling ground penetrating radar application, and is better in detection effect.

Description

Technical Field

[0001] The present invention relates to the technical field of ground penetrating radar antennas, and in particular to an air-coupled dual-polarization combined radar antenna and a transceiver method thereof. Background Art

[0002] With the significant improvement of my country's infrastructure construction capabilities, tunnel construction in the fields of highways, railways, and municipal engineering has continued to advance. According to statistics, by the end of 2020, there were 21,316 highway tunnels in my country with a total tunnel length of 21,999 km; there were 16,798 railway tunnels in operation with a total length of about 19,630 km. At present, the main method for detecting the quality of tunnel lining is to use a manual handheld conventional ground-coupled ground-penetrating radar to detect several measuring lines such as the arch crown, arch waist, side wall and invert.

[0003] At present, some radar manufacturers and application units use vehicle-mounted brackets to fix traditional ground-coupled radars and use non-contact methods for high-speed detection. Due to the low gain of traditional ground-coupled antennas, most of the energy is reflected by the tunnel surface, and the energy of electromagnetic waves penetrating the tunnel lining drops sharply, resulting in a decrease in detection effect.

[0004] Therefore, it is necessary to provide an antenna for a ground penetrating radar suitable for efficient non-contact detection to improve the detection depth and target detection rate. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide an air-coupled dual-polarization combined radar antenna and a transceiver method thereof, so as to solve the problem that the existing radar antenna has a shallow detection depth and a large difference in detection capability for targets in different directions.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions:

[0007] An air-coupled dual-polarization combined radar antenna uses four identical antenna units to form a dual-transmit and two-receive dual-polarization combined antenna through orthogonal combination; the four antenna units include: a first transmitting antenna, a first receiving antenna, a second transmitting antenna and a second receiving antenna; the first transmitting antenna and the first receiving antenna are symmetrical on the left and right; the second transmitting antenna and the second receiving antenna are symmetrical on the top and bottom.

[0008] Furthermore, the first transmitting antenna, the first receiving antenna, the second transmitting antenna and the second receiving antenna form a rectangular area; a "cross"-shaped metal partition is arranged at the center of the rectangular area.

[0009] Furthermore, the metal partition is filled with absorbing blocks made of absorbing materials of corresponding frequency bands. Exemplarily, the absorbing material is polyurethane sponge.

[0010] Furthermore, the first transmitting antenna, the first receiving antenna, the second transmitting antenna and the second receiving antenna are all antipodal Vivaldi antennas with a center frequency of 900 MHz.

[0011] Furthermore, the first transmitting antenna is an HH polarized transmitting antenna; the second transmitting antenna is a VV polarized transmitting antenna; the first receiving antenna is an HH polarized receiving antenna; and the second receiving antenna is a VV polarized receiving antenna. The four antenna units are arranged in a "mouth" shape to achieve detection in two mutually orthogonal polarization directions of HH and VV.

[0012] Furthermore, the first transmitting antenna is composed of a dielectric substrate, an upper radiation patch, a lower radiation patch, a microstrip feed line and a microstrip line ground.

[0013] Furthermore, an upper radiation patch and a microstrip feed line are printed on the front side of the dielectric substrate, and a lower radiation patch having the same shape as the upper radiation patch and a microstrip line floor are printed on the back side of the dielectric substrate.

[0014] Furthermore, the antenna units are all fed by side-inserted radio frequency connectors.

[0015] Furthermore, the microstrip feed line is connected to the inner core of the radio frequency connector; and the microstrip line floor is connected to the external conductor base of the radio frequency connector.

[0016] A transceiving method of an air-coupled dual-polarization combined radar antenna adopts the above-mentioned air-coupled dual-polarization combined radar antenna; the transceiving method comprises the following steps:

[0017] Step S1: The pulse signal generated by the transmitter is fed into the first transmitting antenna and the second transmitting antenna through the coaxial RF cable and the RF connector;

[0018] Step S2: The electromagnetic wave propagates toward the upper radiation patch and the lower radiation patch of the antenna unit through the microstrip line composed of the microstrip feeder and the microstrip line floor; the electromagnetic wave radiates toward the external space through the upper radiation patch and the lower radiation patch;

[0019] Step S3: The electromagnetic waves radiated by the antenna unit enter the first receiving antenna and the second receiving antenna after being reflected by the space target.

[0020] The technical solution of the present invention can achieve at least one of the following effects:

[0021] 1. The present invention orthogonally combines four 900MHz antipodal Vivaldi antennas to achieve the dual-polarization detection function of the radar antenna. In view of the problems existing in the prior art, the air-coupled dual-polarization combined radar antenna provided by the present invention can achieve good detection effects on targets and diseased bodies of different shapes and directions in the tunnel lining and below the ground, and further improve the detection quality on the basis of ensuring the detection efficiency.

[0022] 2. The present invention uses two transmitting antenna units and two receiving antenna units, a total of four antipodal Vivaldi antenna units to form a dual-polarization ground penetrating radar combined transceiver antenna. A "cross" shaped metal partition is set between the antenna units and filled with absorbing materials to reduce the impact of direct waves on the performance of the radar system.

[0023] 3. Compared with the traditional single-polarization ground-penetrating radar antenna, which has extremely weak detection capability for targets orthogonal to its polarization direction, the air-coupled dual-polarization combined radar antenna of the present invention can generate effective echoes for targets in any direction, and the relationship between the installation direction of the antenna, the direction of radar travel (survey line direction) and the direction of the target to be measured no longer affects the radar detection effect. Combined with the air coupling characteristics, the flexible use of ground-penetrating radar is thoroughly realized, the detection efficiency is effectively improved, and the professional threshold for users is lowered, which is conducive to the promotion of radar technology.

[0024] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0026] Figure 1 It is a schematic structural diagram of the air-coupled dual-polarization combined radar antenna of the present invention;

[0027] Figure 2 A top view of the air-coupled dual-polarization combined radar antenna of the present invention;

[0028] Figure 3 A front view of an antenna unit of the air-coupled dual-polarization combined radar antenna of the present invention;

[0029] Figure 4 A back view of an antenna unit of the air-coupled dual-polarization combined radar antenna of the present invention;

[0030] Figure 5 It is a graph of the standing wave ratio actually measured by the antenna unit of the present invention;

[0031] Figure 6 It is a time domain waveform diagram of the antenna unit of the present invention.

[0032] Reference numerals:

[0033] 1-first transmitting antenna; 2-first receiving antenna; 3-second transmitting antenna; 4-second receiving antenna; 5-metal partition; 6-wave absorbing block; 7-fixing strip;

[0034] 11- dielectric substrate; 12- upper radiation patch; 13- lower radiation patch; 14- microstrip feed line; 15- microstrip line floor; 121- inner exponential gradient curve; 122- outer exponential gradient curve. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0036] Example 1

[0037] A specific embodiment of the present invention, as Figure 1 , Figure 2 As shown, an air-coupled dual-polarization combination radar antenna is disclosed, including two antenna units, one transmitting and one receiving, which are symmetrical left and right, and two antenna units, one transmitting and one receiving, which are symmetrical up and down; four identical antenna units are used to form a dual-polarization combination antenna with two transmitting and two receiving through orthogonal combination; the four antenna units include: a first transmitting antenna 1, a first receiving antenna 2, a second transmitting antenna 3, and a second receiving antenna 4; wherein, the first transmitting antenna 1 and the first receiving antenna 2 are symmetrical left and right; and the second transmitting antenna 3 and the second receiving antenna 4 are symmetrical up and down.

[0038] Furthermore, the first transmitting antenna 1, the first receiving antenna 2, the second transmitting antenna 3 and the second receiving antenna 4 form a rectangular area in the shape of a "mouth"; a "cross"-shaped metal partition 5 is arranged at the center of the rectangular area; the "cross"-shaped metal partition 5 is arranged in the middle of the antenna unit of the rectangular structure, and divides the rectangular structure surrounded by the four antenna units into four small rectangular spaces; the four absorbing blocks 6 are respectively filled in the four rectangular spaces surrounded by the antenna units and the metal partition 5; Figure 2 shown.

[0039] Furthermore, the metal partition plate 5 is arranged below the horizontal center lines of the four antenna units.

[0040] Specifically, the shielding partition 5 is made of metal.

[0041] In a specific implementation of the present invention, in order to reduce the direct wave energy and ensure that the metal partition 5 does not affect the operation of the antenna metal radiation patch, the width of the metal partition 5 is 200 mm and the height is 95 mm.

[0042] The present invention arranges a metal shielding partition 5 and a wave absorbing block 6 made of a wave absorbing material according to the radiation characteristics of the antenna, and performs corresponding shielding according to the requirements of the ground penetrating radar system for direct waves.

[0043] Specifically, the metal partition plate 5 is surrounded by wave-absorbing blocks 6 made of wave-absorbing material.

[0044] Specifically, Figure 1 , Figure 2 As shown, the absorbing blocks 6 are four cube-shaped sponge absorbing materials. The four absorbing blocks 6 are arranged around the "cross"-shaped metal partition 5. The absorbing blocks 6 and the metal partition 5 are bonded and fixed by conductive tape.

[0045] Furthermore, two adjacent antenna units are connected via a fixing strip 7; Figure 1 Specifically, the fixing strip 7 is a rectangular strip, and two slits along the length direction of the fixing strip 7 are arranged on two mutually perpendicular sides, and the width of the slits is the same as the thickness of the antenna unit, for installing the antenna unit. Alternatively, two adjacent antenna units are bonded to the fixing strip 7.

[0046] Furthermore, the four antenna units, namely, the first transmitting antenna 1 , the first receiving antenna 2 , the second transmitting antenna 3 and the second receiving antenna 4 , have the same structural design and are all side-fed antipodal Vivaldi antennas with a main frequency of 900 MHz.

[0047] Polarization is one of the important properties of electromagnetic waves, and is another important dimension of information in addition to frequency, amplitude, and phase. The propagation and scattering of electromagnetic waves are both vector phenomena, and polarization is used to study this vector characteristic of electromagnetic waves. The electric field vector of the energy pulse emitted by the radar antenna can be polarized in the vertical or horizontal plane. The radar can send horizontal (H) or vertical (V) electric field vectors, and can also receive horizontal (H) or vertical (V) signals.

[0048] Dual polarization means adding another polarization mode to one polarization mode, such as (HH: horizontal transmission and horizontal reception) and (VV: vertical transmission and vertical reception). Full polarization requires transmitting H and V at the same time, that is, four polarization modes: HH / HV / VV / VH.

[0049] In the present invention, the first transmitting antenna 1 is an HH polarized transmitting antenna; the second transmitting antenna 3 is a VV polarized transmitting antenna; the first receiving antenna 2 is an HH polarized receiving antenna; the second receiving antenna 4 is a VV polarized receiving antenna. In the present invention, the antenna unit switches the polarization mode according to the timing of the electromagnetic signal fed in.

[0050] In the present invention, the first transmitting antenna 1 and the first receiving antenna 2 form HH polarization, and the second transmitting antenna 3 and the second receiving antenna 4 form VV polarization, realizing a dual-polarization combined radar antenna, which can generate effective echoes for targets in any direction, thereby avoiding the limitations of the radar installation direction and the direction of the survey line on the detection results, and breaking through the limitations of the radar in the use process.

[0051] like Figure 3 , Figure 4 As shown, in a specific implementation of the present invention, the first transmitting antenna 1 is composed of a dielectric substrate 11, an upper radiation patch 12, a lower radiation patch 13, a microstrip feed line 14, and a microstrip line ground 15.

[0052] Specifically, an upper radiation patch 12 and a microstrip feed line 14 are printed on the front side of the dielectric substrate 11 , and a lower radiation patch 13 having the same shape as the upper radiation patch 12 and a microstrip line ground plane 15 are printed on the back side.

[0053] Specifically, Figure 3 As shown, the microstrip feed line 14 is a structure with gradually changing width, and the widest end of the microstrip feed line 14 extends to the edge of the dielectric substrate 11 , and the narrowest end is connected to the upper radiation patch 12 .

[0054] like Figure 4 As shown, a lower radiation patch 13 having the same shape as the upper radiation patch 12 and a microstrip line floor 15 are printed on the lower surface of the dielectric substrate 11; the microstrip line floor 15 is a structure with a gradually changing width, the widest end of the microstrip line floor 15 extends to the edge of the dielectric substrate 11, and the narrowest end is connected to the lower radiation patch 13.

[0055] Specifically, the upper radiation patch 12 and the lower radiation patch 13 are distributed symmetrically along the central axis of the radiation direction of the antenna unit.

[0056] In the present invention, the second transmitting antenna 3 has the same structure and shape as the first transmitting antenna 1; the receiving antenna has the same structure as the transmitting antenna, which will not be described in detail here.

[0057] like Figure 3 , Figure 4 As shown, the upper radiation patch 12 and the lower radiation patch 13 are both metal radiation surfaces of the antenna unit and have the same structure and shape.

[0058] Specifically, the shape of the upper radiation patch 12 is surrounded by an inner exponential gradient curve 121 , an outer exponential gradient curve 122 and an arc curve at the end.

[0059] Specifically, the origin of the antenna unit is located at the midpoint of one side of the feed line at the edge of the printed circuit board, that is, the origin corresponding to X=0, Y=0; the antenna radiation direction is placed along the Y-axis, and the Y-axis direction is the antenna width direction (W); the X-axis direction is the antenna length direction (L); and the Z-axis direction is the antenna printed circuit board thickness direction (H).

[0060] Specifically, the dimensions of the dielectric substrate 11 are: length (L) 240 mm*width (W) 180 mm*thickness (H) 2 mm.

[0061] In a specific implementation of the present invention, the curve equation of the inner exponential gradient curve 121 is X1=0.071*exp(0.039*Y1)-0.807, 0≤Y1≤180; the curve equation of the outer exponential gradient curve 122 is X2=0.007*exp(0.001*Y2^2)+0.749, 0≤Y2≤110.

[0062] Specifically, the edge of the upper radiation patch 12 is tangent to two right-angled sides perpendicular to each other of the dielectric substrate 11, and has two tangent points; the curve between the two tangent points is an arc curve; the arc curve is rounded at a right angle between the two right-angled sides of the dielectric substrate 11; the fillet radius of the arc curve is 60 mm.

[0063] Specifically, the position where the inner exponential gradient curve 121 is tangent to the edge of the dielectric substrate 11 is the first tangent point, the position where the outer exponential gradient curve 122 is tangent to the edge of the dielectric substrate 11 is the second tangent point, and the curve between the first tangent point and the second tangent point is an arc curve.

[0064] Specifically, the microstrip feed line 14 and the upper radiation patch 12 of the antenna unit are integrated into a design, and the design parameters of the microstrip feed line 14 are included in an exponential gradient curve. To ensure the welding of the microstrip feed line 14 and the RF connector, the microstrip feed line 14 on the front of the antenna unit is a rectangular strip with a constant width. The width of the microstrip feed line 14 is 1.8 mm.

[0065] Specifically, the microstrip line ground plane 15 on the back of the antenna unit is a structure with a gradually changing width, and its width gradually widens from 1.8 mm to 6.4 mm.

[0066] Specifically, the microstrip line floor 15 adopts an exponential gradient. The microstrip line floor 15 and the lower radiation patch 13 are an integrated structure.

[0067] In the present invention, the radiation surface of the metal radiation surface antenna is distributed on both sides of the printed circuit board, and the two radiation patches are symmetrically distributed along the central axis of the feeding direction of the antenna unit. The feed line is connected to the metal radiation surface to form a continuous whole, and the radiation surface gradually widens from narrow until it is narrowed again through the rounded corner at the end of the printed circuit board to achieve the radiation of electromagnetic waves.

[0068] Specifically, the upper radiation patch 12 and the lower radiation patch 13 are both antipodal Vivaldi antenna radiation patches.

[0069] In a specific implementation of the present invention, the dielectric substrate 11 is made of epoxy resin material with a dielectric constant of 4.3.

[0070] Furthermore, the antenna units are all fed by side-inserted RF connectors. The antipodal Vivaldi transceiver antenna of this embodiment is manufactured by printed circuit board technology, and the antenna is fed by side-inserted SMA-50K RF connectors.

[0071] Specifically, the microstrip feed line 14 is connected to the inner core of the RF connector; and the microstrip line ground plane 15 is connected to the external conductor base of the RF connector.

[0072] At the same time, for the reflection generated by the metal partition 5 and the electromagnetic wave oscillations generated between the metal partition 5 and the first transmitting antenna 1, the first receiving antenna 2, the second transmitting antenna 3, and the second receiving antenna 4, in the present invention, an absorbing block 6 is formed by filling the space between multiple antenna units and the metal partition 5 with absorbing materials suitable for the 900MHz frequency band.

[0073] Specifically, the wave absorbing block 6 is made of a wave absorbing material suitable for the 900 MHz frequency band.

[0074] The present invention adopts two transmitting and two receiving antennas, a total of four antenna units, to form a HH and VV dual polarization arrangement, and designs a metal partition 5 between the transmitting and receiving antennas as a shielding structure and a shielding material as an absorbing block 6. The antenna unit design adopts the antipodal Vivaldi antenna form, and the upper radiation patch 12 and the lower radiation patch 13 of the two arms of the antenna are respectively printed on both sides of the dielectric substrate 11, and the radiation patches all adopt a gradual exponential curve, the radiation patch and the feeder part have a smooth transition, and the rounded corners are processed at the terminal, which greatly reduces the reflection coefficient and reduces the time domain tailing.

[0075] The air-coupled radar antenna of the present invention adopts an air-coupled antenna in a different form from the ground-coupled antenna. The equipment and the antenna are at a greater distance from the surface of the target to be measured, and are not affected by the physical strength of the construction workers and the appendages on the tunnel surface, thereby achieving efficient detection. At the same time, compared with the ground-coupled radar used far away from the surface of the target to be measured, the air-coupled radar antenna can provide a higher gain, thereby improving the signal strength penetrating the tunnel lining.

[0076] Example 2

[0077] A specific embodiment of the present invention provides a transceiver method for the air-coupled dual-polarization combined ground-penetrating radar antenna of Embodiment 1; specifically, the transceiver method includes:

[0078] Step S1: The pulse signal generated by the transmitter is fed into the first transmitting antenna 1 and the second transmitting antenna 3 through the coaxial RF cable and the RF connector;

[0079] Step S2: The electromagnetic wave propagates toward the upper radiation patch 12 and the lower radiation patch 13 of the antenna unit via the microstrip line composed of the microstrip feed line 14 and the microstrip line floor 15; the electromagnetic wave radiates toward the external space through the upper radiation patch 12 and the lower radiation patch 13;

[0080] Step S3: The electromagnetic waves radiated by the antenna unit enter the first receiving antenna 2 and the second receiving antenna 4 after being reflected by the space target.

[0081] In step S1 , the inner core of the RF connector is connected to the upper radiation patch 12 on the front of the antenna unit via a microstrip feeder 14 , and the outer shielding layer thereof is connected to the lower radiation patch 13 via a microstrip line floor 15 .

[0082] In step S1, the electromagnetic waves between the inner and outer cores of the coaxial radio frequency cable are fed into the space between the two conductor layers of the upper radiation patch 12 and the lower radiation patch 13 of the antenna unit through the radio frequency connector.

[0083] In step S2, when the electromagnetic wave propagates toward the terminal (upper radiation patch 12 and lower radiation patch 13) of the antenna unit via the microstrip line composed of the microstrip feed line 14 and the microstrip line ground 15, the electromagnetic wave is confined inside the microstrip line and becomes a guided wave.

[0084] In step S2, the electromagnetic waves are staggered at the upper radiation patch 12 and the lower radiation patch 13 due to the gradual change of the edge curves of the two layers of radiation patches. At this time, the electromagnetic waves gradually break away from the constraints of the upper radiation patch 12 and the lower radiation patch 13, become space electromagnetic waves, and radiate outward.

[0085] In the step S2, when the electromagnetic waves radiate outward, the high-frequency signal begins to radiate outward at the initial staggered position of the upper radiation patch 12 and the lower radiation patch 13, and the lower frequency signal continues to propagate along the upper radiation patch 12 and the lower radiation patch 13 of the metal conductor until radiation is achieved at a larger staggered opening of the upper radiation patch 12 and the lower radiation patch 13 of the antenna unit.

[0086] In step S3, the working principle of the receiving antenna is exactly the same as that of the transmitting antenna, and they are in a reciprocal relationship and can be used interchangeably.

[0087] Specifically, in step S3, when the first receiving antenna 2 and the second receiving antenna 4 receive electromagnetic waves, the electromagnetic waves are captured by the antenna unit through the upper radiation patch 12 and the lower radiation patch 13, and then transmitted to the RF connector through the microstrip feed line 14 and the microstrip ground line 15 and enter the RF cable.

[0088] Furthermore, in order to avoid the influence of spatial reflection on the echo signal, the combined antenna adopts a time-sharing working mode, and its working order is the first transmitting antenna 1-the first receiving antenna 2-the second transmitting antenna 3-the second receiving antenna 4; specifically, the working time interval between the first transmitting antenna 1 and the second transmitting antenna 3 is 5 microseconds.

[0089] like Figure 5 As shown, after testing with a vector network analyzer, the air-coupled dual-polarization combined ground-penetrating radar antenna of the present invention has a standing wave less than 3 above 450 MHz and less than 2 above 700 MHz, and its actual working bandwidth is much greater than 2 GHz.

[0090] like Figure 6 As shown, the time domain waveform of the antenna unit of the present invention is a Ricker sub-wave, the waveform tail is small, and the time domain characteristics are good.

[0091] Compared with the prior art, the technical solution provided by this embodiment has at least one of the following beneficial effects:

[0092] 1. Compared with the traditional ground-coupled ground-penetrating radar butterfly antenna, the air-coupled dual-polarization combined ground-penetrating radar antenna of the present invention has a narrower antenna beam and higher efficiency, and can couple more energy into the interior of the object to be detected, thereby achieving better detection effects. The air-coupling mechanism allows the radar to be separated from the surface of the object to be detected for detection, greatly improving the detection efficiency.

[0093] 2. In ground penetrating radar applications, the direct wave energy between the transmitting and receiving antennas is relatively high, which affects the overall dynamic range of the system. The air-coupled dual-polarization combined ground penetrating radar antenna of the present invention uses a metal partition 5 for isolation to reduce the direct wave energy, and an absorbing block 6 is provided to reduce the energy of reflection and multiple oscillations, and the energy absorbed by the absorbing block 6 is exported through the conductor effect of the metal partition 5, thereby improving the overall performance of the system.

[0094] 3. When the air-coupled dual-polarization combined ground-penetrating radar antenna of the present invention is working, the surface current of the metal radiation patch propagates along the inner exponential gradient curve 121 and the outer exponential gradient curve 122. The curve has rounded corners at the ends, which reduces the sudden structure of the metal and greatly reduces the current reflection, thereby effectively eliminating the time domain tailing of the signal. The signal fidelity is good and it is suitable for ground-penetrating radar applications.

[0095] 4. The present invention realizes an integrated gradient design of the upper radiation patch 12, the lower radiation patch 13, the microstrip feed line 14, and the microstrip ground line 15 of the antenna radiator by accurately designing various parameters of the exponential gradient curve, effectively reducing the energy reflection caused by the sudden change of the feeding structure between the feed line and the antenna, and realizing good impedance matching in an ultra-wide frequency band.

[0096] 5. Compared with the traditional antipodal Vivaldi antenna, the present invention adopts chamfering treatment on the ends of the upper radiation patch 12 and the lower radiation patch 13 of the metal radiator of the antenna unit, which effectively reduces the antenna terminal reflection and the tailing of the ultra-wideband time domain antenna, which is beneficial to improving the performance of the ultra-wideband ground penetrating radar system.

[0097] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An air-coupled dual-polarization combined radar antenna, characterized in that: Four identical antenna units are used to form a dual-polarization combination antenna with two transmit and two receive functions through orthogonal combination; the four antenna units include: a first transmitting antenna (1), a first receiving antenna (2), a second transmitting antenna (3) and a second receiving antenna (4); the first transmitting antenna (1) and the first receiving antenna (2) are symmetrical in left and right; the second transmitting antenna (3) and the second receiving antenna (4) are symmetrical in top and bottom.

2. The air-coupled dual-polarization combined radar antenna according to claim 1, characterized in that: The first transmitting antenna (1), the first receiving antenna (2), the second transmitting antenna (3) and the second receiving antenna (4) form a rectangular area; a "cross"-shaped metal partition (5) is arranged at the center of the rectangular area.

3. The air-coupled dual-polarization combined radar antenna according to claim 2, characterized in that: The area around the metal partition plate (5) is filled with wave absorbing blocks (6) made of wave absorbing materials of the corresponding frequency band.

4. The air-coupled dual-polarization combined radar antenna according to claim 1, characterized in that: The first transmitting antenna (1), the first receiving antenna (2), the second transmitting antenna (3) and the second receiving antenna (4) are all antipodal Vivaldi antennas with a center frequency of 900 MHz.

5. The air-coupled dual-polarization combined radar antenna according to any one of claims 1 to 4, characterized in that: The first transmitting antenna (1) is an HH polarized transmitting antenna; the second transmitting antenna (3) is a VV polarized transmitting antenna; the first receiving antenna (2) is an HH polarized receiving antenna; The second receiving antenna (4) is a VV polarized receiving antenna.

6. The air-coupled dual-polarization combined radar antenna according to claim 1, characterized in that: The first transmitting antenna (1) is composed of a dielectric substrate (11), an upper radiation patch (12), a lower radiation patch (13), a microstrip feed line (14) and a microstrip line floor (15).

7. The air-coupled dual-polarization combined radar antenna according to claim 6, characterized in that: An upper radiation patch (12) and a microstrip feed line (14) are printed on the front side of the dielectric substrate (11), and a lower radiation patch (13) having the same shape as the upper radiation patch (12) and a microstrip line floor (15) are printed on the back side of the dielectric substrate (11).

8. The air-coupled dual-polarization combined radar antenna according to claim 7, characterized in that: The antenna units are all fed by side-inserted radio frequency connectors.

9. The air-coupled dual-polarization combined radar antenna according to claim 8, characterized in that: The microstrip feed line (14) is connected to the inner core of the radio frequency connector; and the microstrip line floor (15) is connected to the external conductor base of the radio frequency connector.

10. A method for transmitting and receiving air-coupled dual-polarization combined radar antenna, characterized in that: The air-coupled dual-polarization combined radar antenna according to any one of claims 1 to 9 is used to transmit and receive signals.

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