Narrow beam low profile array antenna for millimeter wave radar for well ranging

Abstract

The present invention discloses a narrow beam low-profile array antenna applied to a millimeter-wave radar for ranging in a well, and provides a new design scheme for a ranging antenna in a well. The narrow beam low-profile antenna array for ranging in a well of the present invention comprises: a microstrip series-fed array antenna and a T-junction feeding structure. The application of the invention is to use a millimeter-wave radar to detect the water level underground. Since the water level is not far from the manhole cover and the diameter of the manhole cover is small, the beam of the traditional side-fed array antenna is wide and cannot meet the requirements of detecting the water level. It is necessary to invent a non-high-gain pencil beam array antenna structure. The above-mentioned pencil beam array antenna structure uses a microstrip T-junction to feed in the middle of the antenna, which can increase the number of array elements of the antenna series feed to achieve the purpose of reducing the beam width. This pencil beam array antenna is more suitable for millimeter-wave radar to detect water levels underground.

Description

Technical Field

[0001] The invention relates to the technical field of array antennas, in particular to a microstrip array antenna in the form of a T-junction intermediate-fed, low-profile, ultra-narrow beam. Background Art

[0002] In recent years, with the rapid development of array antennas, MIMO technology, millimeter-wave radar technology, etc., the usage rate of millimeter-wave array antennas has become increasingly higher, which has put forward requirements for miniaturization, narrow beam, high gain, etc. for the antenna arrays in radar RF boards.

[0003] Microwave antennas, as the interface between millimeter-wave radar and the magnetic field in space, play a vital role in the characteristics, performance and application of radar products. Traditional millimeter-wave transceiver equipment mostly uses horn antennas or waveguide feeds as the end of microwave transceivers, which are large in size and high in cost, making them unsuitable for vehicle-mounted conditions. Microstrip array antennas refer to antennas made using microstrip technology on printed circuits, and are mainly used in microwave frequency bands. Microstrip array antennas have the advantages of small size, high efficiency, low cost and easy production, and therefore have become the preferred antenna technology for emerging millimeter-wave radars.

[0004] For underground water level measurement, the water level is generally not far from the manhole cover, so there is no high requirement for antenna gain. However, the diameter of the manhole cover is relatively small, so the antenna beam is required to be very narrow. The traditional side-fed microstrip array antenna can only have a limited number of patch units and cannot achieve a narrow beam. This has some limitations for well ranging or some application scenarios that require ultra-narrow pencil beams. Summary of the invention

[0005] In order to solve the problems in the above background technology, we need to invent a pencil beam array antenna which is fed from the middle of the antenna by a T-junction, so that the microstrip array antenna of the present invention has the characteristics of high gain, ultra-narrow beam and good directivity.

[0006] The first object of the present invention is to provide a series-fed microstrip array antenna, comprising a dielectric substrate and a patch array antenna located on the dielectric substrate, wherein the patch array antenna comprises a plurality of rectangular radiators connected in series, wherein the plurality of rectangular radiators are connected to each other through a microwave feeder and are pulled out in the middle of the antenna for feeding through a T-junction feeding structure. The T-junction feeding structure comprises a power divider structure that is centrally symmetrical, and the T-junction also comprises a 180-degree phase shifter, and the plurality of rectangular radiators are symmetrically arranged in a straight line relative to the feeding structure.

[0007] Furthermore, every two adjacent rectangular radiators are distributed at unequal intervals, and the transverse midlines of all the rectangular radiators coincide with each other, and the transverse midline of the rectangular radiator coincides with the transverse midline of the microwave feeder.

[0008] Furthermore, the lateral lengths of the multiple rectangular radiators are the same, the longitudinal widths of the rectangular radiators of the single linear patch array antenna located at both ends of the feeding structure are the largest, and the longitudinal widths of the multiple rectangular radiators gradually decrease along the directions of the two ends of the antenna.

[0009] Furthermore, there are two instances of a single linear patch array antenna, which respectively include 12 rectangular radiators and 40 rectangular radiators.

[0010] Furthermore, the length Lp and width Wp of the rectangular radiator are determined by the following calculation formula:

[0011]

[0012] in: c is the speed of light, f0 is the center frequency of the specified frequency band, ε r is the dielectric constant of the dielectric substrate, and h is the thickness of the dielectric substrate.

[0013] The second object of the present invention is to propose a center-fed combined microstrip array antenna structure, each of which includes two of the above-mentioned patch array antennas, and the two patch array antennas are connected by a T-junction feeding structure including an inverter, and the feeding structure and the patch array antenna are both located on a dielectric substrate.

[0014] The present invention includes two examples, one of which includes 12 center-fed combined microstrip array antenna structures, which are placed in parallel along the lateral direction of the dielectric substrate. Each center-fed combined array antenna structure includes two patch array antennas, which are equidistantly distributed along the vertical direction of the dielectric substrate, and each patch array antenna includes 12 rectangular radiators; the other example includes 40 center-fed combined microstrip array antenna structures, which are placed in parallel along the lateral direction of the dielectric substrate. Each center-fed combined array antenna structure includes two patch array antennas, which are equidistantly distributed along the vertical direction of the dielectric substrate, and each patch array antenna includes 40 rectangular radiators.

[0015] Preferably, the distance between two adjacent center-fed combined antennas is 0.8λ.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The serial-fed microstrip array antenna of the present invention adopts serial feeding and has a high gain in the specified millimeter wave frequency band. At the same time, due to the use of a center-fed combined array antenna structure, the beam width of the antenna is very narrow, and it is a pencil-shaped beam. It is suitable for application scenarios with a narrow lateral detection range, such as underground water level ranging. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A top view of a single-line microstrip array antenna structure provided in Example 1 of the present invention;

[0019] Figure 2 A top view of a center-fed combined microstrip array antenna structure provided in Example 1 of the present invention;

[0020] Figure 3 A top view of a single-line microstrip array antenna structure provided in Example 2 of the present invention;

[0021] Figure 4 A top view of a center-fed combined microstrip array antenna structure provided in Example 2 of the present invention;

[0022] Figure 5 Return loss diagram of the narrow beam low profile array antenna provided in Example 1 of the present invention;

[0023] Figure 6 Return loss diagram of the narrow beam low profile array antenna provided in Example 2 of the present invention;

[0024] Figure 7 The directional pattern of the narrow beam low profile array antenna provided in Example 1 of the present invention;

[0025] Figure 8 The directional pattern of the narrow beam low profile array antenna provided in Example 2 of the present invention; DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and embodiments. A part of the embodiments of the present invention is provided in the accompanying drawings, rather than all the embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without paying creative work are within the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0028] Example 1

[0029] Figure 1 is a top view of a single-string microstrip array antenna in Example 1, Figure 2 The top view of the 12*12 center-fed combined microstrip array patch antenna. Figure 1 As shown, the single-line array antenna comprises a dielectric substrate (11), six series-connected rectangular radiators (12) whose longitudinal widths gradually decrease along the two ends of the antenna, a quarter-wavelength impedance transformer (13) and six sections of microwave feed lines (14) connecting the rectangular radiators. Figure 2 As shown, there are 12 above-mentioned Figure 1 A single-string microstrip array antenna, with two symmetrical inverter structures (15) along 180 degrees in the longitudinal direction, and also includes a T-junction feeding structure (16) (17). In this example, there are 24 identical Figure 1 The antenna array shown in FIG. 1 is symmetrically distributed laterally and longitudinally along the T-junction feeding structure. Figure 1 The single-string microstrip array antenna in the embodiment works in a quasi-TEM mode. Generally, the longitudinal spacing between the two rectangular radiators (12) is one dielectric wavelength, and the longitudinal length of each rectangular radiator (12) is approximately half a dielectric wavelength. The two longitudinal patch edges of the rectangular radiator (12) can be equivalent to two gaps, and the energy of the radiation field is also mainly generated in the gap between the edge of the radiator and the ground plane. This example uses a T-junction intermediate feed, and two identical symmetrical series feeds are longitudinally along the T-junction. Figure 1 Compared with the traditional side-feeding method, the single-string microstrip array antenna has more rectangular radiator units connected in series, which can obtain a narrower beam width in the vertical radiation overhead direction. Since the radiating edges of the two rectangular radiators on the same side of the serial-fed patch array antenna are one dielectric wavelength apart, an inverter structure needs to be added where the T-junction feeding structure is connected to the single-string microstrip array antenna on the other side to ensure the serial feeding state. Figure 5 The figure shows the return loss diagram of the feeding structure port of the combined microstrip array antenna in Example 1. It can be seen that the feeding structure realizes energy transmission very well. Figure 6 The figure shows the radiation pattern of the narrow beam low-profile array antenna provided in Example 1. It can be seen that both radiating surfaces have high-gain and very narrow pencil beams, which can meet the requirements of underground water level detection.

[0030] Example 2

[0031] Figure 3 is a top view of a single-string microstrip array antenna in Example 2 of the present invention, Figure 4 The top view of the 40*40 center-fed combined microstrip array patch antenna. Figure 3As shown, the single-line array antenna comprises a dielectric substrate (21), 20 rectangular radiators (22) connected in series, the longitudinal width of which gradually decreases along the two ends of the antenna, a quarter-wavelength impedance transformer (23) and 20 sections of microwave feed lines (24) connecting the rectangular radiators. Figure 4 As shown, there are 20 above-mentioned wavelengths 0.8 apart in the lateral direction. Figure 3 A single-string microstrip array antenna, with two symmetrical inverter structures (25) along 180 degrees in the longitudinal direction, and also includes a T-junction feeding structure (26) (27). In this example, there are 40 identical Figure 1 The antenna array shown in FIG. 1 is symmetrically distributed laterally and longitudinally along the T-junction feeding structure. Figure 1 The single-string microstrip array antenna in the embodiment works in a quasi-TEM mode. Generally, the longitudinal spacing between the two rectangular radiators (22) is one dielectric wavelength, and the longitudinal length of each rectangular radiator (22) is approximately half a dielectric wavelength. The two longitudinal patch edges of the rectangular radiator (22) can be equivalent to two gaps, and the energy of the radiation field is also mainly generated in the gap between the edge of the radiator and the ground plane. This example uses a T-junction intermediate feed, and two identical symmetrical series feeds are longitudinally along the T-junction. Figure 3 Compared with the traditional side-feeding method, the single-string microstrip array antenna has more rectangular radiator units connected in series, which can obtain a narrower beam width in the vertical radiation overhead direction. Since the radiating edges of the two rectangular radiators on the same side of the serial-fed patch array antenna are one dielectric wavelength apart, an inverter structure needs to be added where the T-junction feeding structure is connected to the single-string microstrip array antenna on the other side to ensure the serial feeding state. Figure 7 The figure shows the return loss diagram of the feeding structure port of the combined microstrip array antenna in Example 1. It can be seen that the feeding structure realizes energy transmission very well. Figure 8 The figure shows the radiation pattern of the narrow beam low-profile array antenna provided in Example 2. It can be seen that both radiating surfaces have high-gain and very narrow pencil beams, which can meet the requirements of underground water level detection.

[0032] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A narrow beam low profile array antenna for millimeter wave radar used for ranging in wells, characterized in that The invention comprises a dielectric substrate and a patch array antenna on the dielectric substrate, wherein the patch array antenna comprises a plurality of center-fed combined microstrip array antenna structures, each center-fed combined microstrip array antenna structure comprises two single-string series-fed microstrip patch array antennas, each single-string series-fed microstrip patch array antenna comprises a plurality of rectangular radiators, and the plurality of rectangular radiators are connected to each other through microwave feed lines. The plurality of single-series serial-fed microstrip patch array antennas are symmetrically distributed in the transverse and longitudinal directions along a T-junction feeding structure including an inverter, wherein for each center-fed combined microstrip array antenna structure, the two single-series serial-fed microstrip patch array antennas included therein are connected through the T-junction feeding structure, and the plurality of rectangular radiators of the two single-series serial-fed microstrip patches are symmetrically arranged in a straight line relative to the T-junction feeding structure, so as to symmetrically serially feed the two single-series serial-fed microstrip patches in the center-fed combined microstrip array antenna structure along the T-junction feeding structure in the longitudinal direction, The T-junction feeding structure includes a centrally symmetrical power divider structure, which realizes more series-fed units that cannot be reached by side feeding, and finally realizes a high-gain pencil beam.

2. The narrow beam low profile array antenna according to claim 1, characterized in that: Every two adjacent rectangular radiators are distributed at unequal intervals, and the transverse midlines of all the rectangular radiators coincide with each other, and the transverse midlines of the rectangular radiators and the microwave feeder line coincide with each other.

3. The narrow beam low profile array antenna according to claim 1, characterized in that: The lateral lengths of the multiple rectangular radiators are the same, the longitudinal widths of the rectangular radiators of the single linear patch array antenna located at both ends of the feeding structure are the largest, and the longitudinal widths of the multiple rectangular radiators gradually decrease along the directions of the two ends of the antenna.

4. The narrow beam low profile array antenna according to any one of claims 1 to 3, characterized in that: There are two examples of a single linear patch array antenna, which include 12 rectangular radiators and 40 rectangular radiators respectively.

5. The narrow beam low profile array antenna according to any one of claims 1 to 3, characterized in that: The length Lp and width Wp of the rectangular radiator are determined by the following calculation formula: in: c is the speed of light, f0 is the center frequency of the specified frequency band, ε r is the dielectric constant of the dielectric substrate, and h is the thickness of the dielectric substrate.

6. A center-fed combined microstrip array antenna structure, characterized in that: Each center-fed combined microstrip array antenna structure includes two single-string series-fed microstrip patch array antennas as described in any one of claims 1 to 5, and the two single-string series-fed microstrip patch array antennas are connected through a T-junction feeding structure including an inverter, and the feeding structure and the single-string series-fed microstrip patch array antennas are both located on a dielectric substrate.

7. The center-fed combined microstrip array antenna structure according to claim 6, characterized in that: It includes 12 center-fed combined microstrip array antenna structures, which are placed in parallel along the lateral direction of the dielectric substrate. Each center-fed combined microstrip array antenna structure comprises two single-series series-fed microstrip patch array antennas, the two single-series series-fed microstrip patch array antennas are equidistantly distributed along the vertical direction of the dielectric substrate, and each single-series series-fed microstrip patch array antenna comprises 12 of the rectangular radiators; or It contains 40 center-fed combined microstrip array antenna structures, which are placed in parallel along the lateral direction of the dielectric substrate. Each center-fed combined microstrip array antenna structure includes two single-string series-fed microstrip patch array antennas, which are equidistantly distributed along the vertical direction of the dielectric substrate, and each single-string series-fed microstrip patch array antenna includes 40 of the rectangular radiators.

8. The center-fed combined microstrip array antenna structure according to claim 7, characterized in that: The distance between two adjacent center-fed combined microstrip array antenna structures is 0.8λ.

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