KR20100113347A - The series-fed array antenna for ultra high frequency band radar - Google Patents

Abstract

PURPOSE: A DC feeding array antenna for an ultra high frequency band radar is provided to improve an antenna radiation gain, a low peak sidelobe level, and a deviation property. CONSTITUTION: A center feeding point(4) is formed in the center of a micro strip line. A matching stub(2) is formed in one end of the center feeding point. A transmission line(3) transfers a current from the center feeding point to each antenna radiation element(1). The antenna radiation element is symmetrically formed around the central feeding point.

Description

The series-fed array antenna for ultra high frequency band radar

The present invention relates to an ultra high frequency band radar antenna, and more particularly, to the antenna design of a portable super high frequency band radar, a thin, light weight having a central series feed structure with improved antenna radiation gain, low side lobe level, and polarization characteristics. The present invention relates to a low cost series feed array antenna.

For example, the present invention uses a microstrip line-based central series feed, a polarization technique for distinguishing metallic and non-metallic objects, and a matching stub for minimizing discontinuity of array antennas and antenna matching. The present invention relates to a series feed array antenna for an ultra high frequency radar.

The present invention is derived from a study conducted as part of the regional innovation workforce training project of the Ministry of Education, Science and Technology and the Korea Industrial Technology Foundation. [Task management number: N02086351, Task name: Development of portable multi-function monitoring x-band radar].

Recent wireless communication technologies are being used for various applications, and the application field is radar detection.

Radar detection is a technology that primarily detects metallic objects, such as tracking missiles launched from a specific area or measuring the speed of a moving vehicle.

In radar detection, signals in the ultra high frequency band such as X-band [10.525 ± 0.05 GHz], K-band [24.150 ± 0.125 GHz], and KA-band [34.7 GHZ ± 0.3 GHz] are generally used.

On the other hand, the design of the array antenna (array antenna) is important to implement a radar detection device (ultra high frequency band radar) excellent in the detection of metallic objects. In other words, antenna radiation gain and side lobe level should be considered when designing array antenna of radar.

Generally, waveguides, microstrip lines or mixed structures are used to implement radar array antennas. Here, a series-fed is mainly used as an antenna feeding method, and as an advantage thereof, antenna design is easy and low side lobe level characteristics can be obtained.

US Patent No. 7,091,921 (name of invention: "Travelling wave combining array antenna apparatus") (hereinafter referred to as "prior art 1"), US Patent No. 4,180,817 (name of invention: "Serially Connected Microstrip Antenna Array" ") [Hereinafter referred to as" prior art 2 ") shows an array antenna.

In the related art 1, power is supplied from the center to the antenna radiating element so that radio waves propagate to both ends of the antenna array to generate radiation. At this time, the current distribution is formed from the center to both ends, and has a distribution showing the magnitude of the largest current at the center and the magnitude of the smallest current at both ends, thereby improving the low side lobe level characteristics.

By the way, the array antenna structure proposed in the prior art 1 is limited to only the one-dimensional array antenna, and does not suggest the structure of the two-dimensional array antenna at all, and there is a problem in that the polarization characteristic is not improved.

On the other hand, the prior art 2 proposes a structure of a two-dimensional array antenna using a series feed.

However, the array antenna structure proposed in the prior art 2 does not remove a beam squint phenomenon which is fundamentally generated in the series feed, and there is a problem in that it does not improve the polarization characteristics as in the prior art 1.

Therefore, the present invention has been proposed to solve the above problems and to meet the above requirements, the center of the antenna radiation gain, low side lobe level, polarization characteristics in the antenna design of the ultra-high frequency band radar for portable monitoring An object of the present invention is to provide a thin, light weight, low cost series feed array antenna having a series feed structure.

For example, the present invention uses a microstrip line-based central series feed, a polarization technique for distinguishing metallic and non-metallic objects, and a matching stub for minimizing discontinuity of array antennas and antenna matching. The aim is to provide a series feed array antenna for an ultra high frequency radar.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

According to an aspect of the present invention, there is provided an ultra-high frequency radar antenna, comprising: a center feeding point formed at a center on a micro strip line; A transmission line for transferring current from the central feed point to each antenna radiating element; And the plurality of antenna radiating elements formed in a two-dimensional array symmetrically left / right / up / down about the center feeding point, and to ensure the same phase of the antenna radiating elements serially fed left / right, The length of the transmission line connecting the right antenna radiating element and the transmission line connecting the left antenna radiating element has a distance difference of half wavelength from the center feeding point, and the same phase of the antenna radiating element fed in series up and down. In order to ensure, the length of the transmission line connecting the upper antenna radiating element and the transmission line connecting the lower antenna radiating element is characterized by having a distance difference of one wavelength from the central feeding point.

The present invention further includes a matching stub formed at one end of the center feed point for antenna matching.

As described above, the present invention provides an antenna radiation gain characteristic, a low side lobe level characteristic capable of suppressing a signal in an undesired direction, a performance capable of distinguishing a metallic object from a nonmetallic object, minimizing discontinuity intervals of an array antenna, and efficient antenna matching. This has the effect of improving performance.

In addition, the present invention can manufacture a thin, light weight, low-cost serial feed array antenna, through which there is an effect to implement a super high frequency band radar for portable monitoring.

The above objects, features, and advantages will become more apparent from the detailed description given hereinafter with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains may share the technical idea of the present invention. It will be easy to implement. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of an embodiment of a series feed array antenna for an ultra-high frequency band radar according to the present invention, Figure 2 is a transmission / reception antenna system of a portable super-high frequency band radar implemented in accordance with the present invention An illustration of one embodiment.

As shown in FIG. 2, the antenna of the present invention is a polarization selective antenna, which includes a transmitting antenna and a receiving antenna, and uses a polarization generating technique for distinguishing a metallic object from a nonmetallic object.

FIG. 1 illustrates a part of the transmit / receive antenna of FIG. 2, that is, an antenna radiating element symmetrically disposed left / right / upper / down about a central feeding point in the transmitting or receiving antenna of FIG. 2. Some of the are illustrated. Hereinafter, the present invention will be mainly described with reference to FIG. 1 to facilitate understanding of the present invention.

In addition, the antenna proposed in the present invention preferably uses an ultra-high frequency band such as an X-band, a K-band, a KA-band, etc., but it is clear that the antenna is not limited to a specific frequency band.

As shown in FIG. 1, a series feed array antenna for an ultra high frequency band radar according to the present invention includes a center feed point 4 and a center feed point 4 formed at a (positive) center on a microstrip line. A matching stub 2 (for matching at the center feed point) formed at one end of the c), for delivering current from the center feed point 4 to each antenna radiating element 1 (center feed point). Transmission line (3) for the connection between the antenna and the antenna radiating element, the connection between the antenna radiating element, and a plurality of antenna radiating elements formed symmetrically in the left, right, up, and down about the center feed point (4) radiating element (aka patch antenna) 1 and the like.

First, some of the technical features of the present invention will be mentioned.

In the present invention, the series feed is used to improve the antenna radiation gain and low side lobe level characteristics, and starts at the center feed point 4 in the center of the array antenna on the microstrip line in order to solve the beam shift phenomenon occurring during the series feed. Power supply up / down / left / right via the transmission line (3). In addition, the side lobe level (SLL) refers to the relative difference between the main lobe and the side lobe.

In addition, the present invention uses a polarization technique by cutting the diagonal edges of each antenna radiator element 1 to distinguish between metallic objects and nonmetallic objects. For example, in the present invention, a polarization technique is used to attenuate (remove unwanted noise signals) a non-metallic reflection signal.

In addition, in the present invention, a matching stub 2 is provided at the center feeding point 4 to minimize discontinuity of the array antenna and to match the antenna, thereby facilitating matching.

That is, in the present invention, an antenna for an ultra high frequency band radar (for example, an X-band radar) is designed as a micro strip line so that the antenna can be manufactured in a low profile, light weight, and low cost. Implementation of Radar Antenna], Antenna's Array Structure, Matching Technique, Feeding Structure, and Polarization Technique to improve antenna radiation gain, low side lobe level, and polarization characteristics as well as metallic object detection performance.

The antenna array structure, polarization generating structure, and antenna matching structure proposed by the present invention will be described in detail as follows.

(1) antenna array structure

A typical antenna array structure has a structure in which the number of arrays of antenna radiating elements is increased by a multiple of 2. However, the number of array antenna radiating elements may not be maximized in a relatively limited size. The array antenna of the series feed structure can flexibly adjust the number of antenna radiating elements to maximize the area allocated to the antenna design, and the side lobe level can be adjusted by adjusting the current distribution. However, as described above, in the conventional technologies (when the array antenna is implemented by the micro strip line with the serial feeding structure), the beam shifting phenomenon cannot be eliminated.

Accordingly, in the present invention, a feed point is formed at the center of the array antenna on the micro strip line to maximize the antenna design area, and have a two-dimensional antenna radiating element array structure that eliminates the beam shift phenomenon.

That is, a structure in which a plurality of antenna radiating elements 1 are serially fed as a two-dimensional array symmetrically to the left / right / up / down about the center feed point 4, for example, a structure that is symmetrically fed left / right. Since the structure of feeding up and down has symmetry, the beam shift phenomenon is eliminated, and the radiation effect generated from the transmission line 3 has a structure capable of lowering the side lobe level on the stem as much as possible.

(2) a structure that generates polarization

The signal received by the radar antenna may also receive various noises in addition to the signal of the desired detection object. Such noise signals may be removed through signal processing, but the complexity of the radar may be increased due to the signal processing.

Therefore, the present invention uses a polarization technique that can remove a noise signal received from the antenna, independently of the signal processing performed at the rear end of the antenna.

In other words, in the case where the radar antenna transmits a right circularly polarized wave (RHCP) and receives a left circularly polarized wave (LHCP) (or vice versa), it is possible to effectively remove a noise signal in detecting only a metallic object. Can be.

The principle of noise reduction is that, when a progressive circular polarization hits and reflects a metallic object, the circular polarization is maintained but the left circular polarization is converted to the right polarization, the right circular polarization is converted to the left circular polarization, and the ongoing circular polarization is nonmetallic. When hitting and reflecting an object (high dielectric constant object), the axial ratio of the reflected wave is also converted, thereby reducing noise sensitivity by reducing signal sensitivity at the radar antenna. In addition, circular polarization is a case where two directional components of a traveling electric field have the same magnitude while the phases of the two polarizations (horizontal and vertical) differ by 90 °. Here, if the phase difference is + 90 °, it is divided into left circle polarization and -90 °. On the other hand, the relative magnitude ratio of the two polarizations is called the axial ratio. In the case of the circular polarization, the axial ratio is 1 since the two polarizations have the same magnitude.

(3) antenna matching structure

Typically, 50 [ohm] is fitted at each fed junction for antenna matching, and discontinuity occurs at each of these nodes. Even at such discontinuities, weak radiation occurs, acting to increase the levels of the side lobes.

Therefore, in the present invention, instead of making a discontinuous portion on the transmission line so as to effectively match while removing such discontinuity points, the transmission line has the same structure continuously [periodically] to minimize the discontinuity point, and The matching stub is provided at the feed point to minimize the discontinuity point of the entire array antenna, and has a structure that can efficiently match.

Next, an antenna array structure, a polarization generating structure, an antenna matching structure, and the like described in the present invention will be described in detail with reference to FIGS. 3 to 7.

FIG. 3 is a conceptual diagram for explaining a polarization generation technique proposed by the present invention. FIG. 4 is a detailed configuration diagram of an antenna radiating element for polarization generation according to the present invention. FIG. 1 is a detailed configuration diagram of a matching stub for antenna matching according to the present invention. FIG. 6 is a cross-sectional view of an embodiment of a feeding point of a microstrip line-based series feeding array antenna according to the present invention. Is a diagram illustrating an embodiment of a left and right feeding structure for the same input impedance proposed in the present invention.

As shown in Fig. 3 and Fig. 4, in the present invention, the diagonal edges of each antenna radiator element 1 are cut off, for example, for the transmitting antenna, the corners of the upper right part and the lower left part of the antenna radiator element. And cut the corners of the upper left portion and the lower right portion of the antenna radiator element with respect to the receiving antenna. And vice versa].

When the diagonal corners of the antenna radiator element 1 are cut as described above, two modes are generated in the antenna. The frequencies f1 and f2 generated in each mode have a constant magnitude and phase, and the two mode sizes When the phases are 90 ° out of phase, the antenna can generate circular polarizations. Meanwhile, when the two modes do not have the same size, elliptical polarization may be generated in the antenna. In addition, elliptical polarization is a case where two directional components of an electric field progress, but the magnitude of the two polarizations (horizontal and vertical) are different by 90 °. In the case of elliptical polarization, the magnitude of the two polarizations is different so that the axial ratio is one or more.

In addition, in Fig. 4, reference numeral 10 denotes a transmission line connecting the antenna radiating elements (antenna arrangement).

Meanwhile, as shown in FIG. 5, a matching stub 2 is provided at one end of the center feeding point 4. In FIG. 5, reference numeral 7 denotes a transmission line fed to the upper end, and reference numeral 8. ) Denotes transmission lines fed to the bottom, respectively.

6 shows a portion of the center feed point 4 viewed from the side by cutting the antenna of the present invention, which is arranged on the microstrip line and on the upper layer of the PCB substrate 14 for supporting the array antenna pattern. An antenna pattern 12 is formed, a metal panel 15 for supporting an array antenna is formed below the PCB substrate 14, a connector inner core 13 for feeding power to the center of the array antenna, and an SMA port for feeding power. Or coaxial cable port 16 is formed.

Meanwhile, FIG. 7 illustrates an arrangement of the left / right symmetrically formed antenna radiating elements 1 shown in FIG. 1, and for the convenience of description of the present invention, the right antenna radiating element 1 is placed on the top of FIG. 7. The arrangement is shown the arrangement of the left antenna radiating element 1 at the bottom of FIG.

]의 거리차를 갖도록 구현, 즉 좌측 안테나 방사 소자 연결 전송 선로의 길이가 우측 안테나 방사 소자 연결 전송 선로의 길이보다 반 파장 더 길게 구현한다.As shown in FIG. 7, in the present invention, a transmission line for connecting antenna radiating elements fed in series in left and right (17 is a right antenna radiating element connecting transmission line, and 18 is a left antenna radiating). In terms of the length of each component-connected transmission line], in order to ensure the in-phase of the antenna radiating element fed left / right.

], That is, the length of the left antenna radiating element connection transmission line is half wavelength longer than the length of the right antenna radiating element connection transmission line.

]]의 거리차를 갖도록 구현, 즉 상측 안테나 방사 소자 연결 전송 선로의 길이가 하측 안테나 방사 소자 연결 전송 선로의 길이보다 한 파장 더 길게 구현한다.In addition, in the present invention as shown in Figure 1 in order to determine the length of the transmission line for connecting the antenna radiating element fed in series up and down, in order to ensure the same phase of the antenna radiating element fed up and down One wavelength at feed point [

]] Such that the length of the upper antenna radiating element connecting transmission line is one wavelength longer than the length of the lower antenna radiating element connecting transmission line.

Although the antenna radiating element fed left and right has a distance difference of half wavelength and the antenna radiating element fed up and down has a distance difference of one wavelength as described above, the current distribution in each antenna radiating element exhibits the same input impedance. It is the structure which can make phase same. That is, in the microwave band, the input impedance is equalized by half wavelength period or one wavelength period. This means that the input impedances Z _a and Z _b are the same as shown in FIG. 7 [Z _a = Z _b ].

Next, the numerical values required for the antenna design of the present invention shown in FIGS. 1 to 7 are shown in the following [Table 1], and the unit is millimeter [mm]. In addition, in consideration of the antenna radiation gain, low side lobe level, polarization characteristics, and the like, it is preferable that the numerical values necessary for the antenna design are variably set without being limited to the following Table 1.

Finally, the antenna performance evaluation results of the present invention as described above will be described with reference to FIGS. 8A, 8B, 9 and Table 2 below.

Antenna performance evaluation target is a transmission and reception antenna system of a portable super-high frequency band radar implemented as shown in Figure 2, the size is 230 × 360 [mm ² ], the dielectric constant 2.2 [loss tangent = 0.004], thickness on the microstrip line substrate 0.508 [mm], the total number of antenna radiating elements were 160, each antenna radiating element was made as a square of the same size, and the width of the transmission line was 1.5 [mm].

8A and 8B are graphs illustrating an example of evaluating the radiation pattern performance of the serially fed array antenna according to the present invention, and FIG. 9 is a reflection loss performance of the serially fed array antenna according to the present invention. An example graph is shown.

8A shows the zx plane radiation pattern of the antenna of the present invention, and FIG. 8B shows the xy plane radiation pattern of the antenna of the present invention, and FIG. 9 shows the reflection loss characteristics of the antenna of the present invention. Shows the result of antenna emission gain, side-level characteristics, and bandwidth.

]에서 -16.1[dB] 및 zy 평면[

]에서 -19.0[dB], 축비는 6[dB], 대역폭은 10[GHz]에서 2% 이상을 나타내었다. 덧붙여, 대역폭은 중앙 급전 지점에서의 정합 스터브의 튜닝을 통해 확장될 수 있다.As can be seen from the simulation and comparative measurements of FIGS. 8A, 8B, 9 and Table 2, the measured antenna radiation gain is 25.2 [dBi], and the side lobe level is the zx plane [

] At -16.1 [dB] and zy plane [

] Was -19.0 [dB], the axis ratio was 6 [dB], and the bandwidth was more than 2% at 10 [GHz]. In addition, the bandwidth can be extended through tuning of the matching stub at the center feed point.

On the other hand, the side lobes shown in the zx plane and the yz plane are somewhat different due to different ratios r.The zx plane shows a flat response even though the side lobes are nearly identical in size and somewhat inconsistent between simulation and comparative measurements. It can be seen that this gradually decreases.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

1 is a diagram illustrating an embodiment of a series feed array antenna for an ultra high frequency band radar according to the present invention.

Figure 2 is an embodiment explanatory diagram for illustrating a transmission and reception antenna system of a portable super-high frequency band radar implemented in accordance with the present invention.

3 is a conceptual diagram illustrating an embodiment of a polarization generation technique proposed by the present invention.

Figure 4 is a detailed configuration diagram of an embodiment of the antenna radiating element for polarization generation proposed in the present invention.

Figure 5 is a detailed configuration diagram of an embodiment of a matching stub for antenna matching proposed in the present invention.

6 is a cross-sectional view of an embodiment of a feed point of a micro strip line based series feed array antenna according to the present invention.

7 is a diagram illustrating an embodiment of a left and right feeding structure for the same input impedance proposed in the present invention.

8a and 8b is an embodiment graph for showing the radiation pattern performance evaluation results of the series feed array antenna presented in the present invention.

Figure 9 is an embodiment graph for showing the return loss performance evaluation results of the series feed array antenna proposed in the present invention.

* Explanation of symbols on the main parts of the drawing

1: antenna radiating element

2: matching stub

3: transmission line

4: center feed point

Claims (6)

In the ultra high frequency radar antenna, A central feed point formed centrally on the micro strip line; A transmission line for transferring current from the central feed point to each antenna radiating element; And And a plurality of antenna radiating elements formed in a two-dimensional array symmetrically to the left / right / up / down about the central feeding point, The distance between the transmission line connecting the right antenna radiating element and the transmission line connecting the left antenna radiating element is the distance difference of half wavelength from the center feeding point to ensure the same phase of the antenna radiating element fed in series left / right. To have, In order to ensure the same phase of the antenna radiating element fed up and down in series, the distance between the transmission line connecting the upper antenna radiating element and the transmission line connecting the lower antenna radiating element is the distance difference of one wavelength from the center feeding point. Serial feeding array antenna for ultra-high frequency band radar, characterized in that having a. The method of claim 1, Matching stub formed at one end of the center feed point for antenna matching Serial feeding array antenna for ultra-high frequency band radar further comprising. The method of claim 1, Each antenna radiating element, A series feed array antenna for an ultra high frequency band radar, characterized by having a square shape having the same size. The method of claim 3, wherein Each antenna radiating element, 2. A series feed array antenna for ultra high frequency band radar, characterized in that both corners in a diagonal direction are cut to a predetermined size for polarization generation. The method of claim 4, wherein The polarization is, A series feed array antenna for ultra high frequency band radar, characterized in that it is circularly polarized or elliptically polarized. The method of claim 1, The ultra high frequency band, A series feed array antenna for an ultra high frequency band radar, characterized in that at least one of X-band, K-band, KA-band.

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