A uniformly distributed radiated energy structure for a millimeter-wave antenna

Abstract

This invention discloses a uniformly distributed radiation energy structure for a millimeter-wave antenna, comprising a transmitting array antenna and / or a receiving array antenna composed of at least one comb-shaped antenna assembly; the comb-shaped antenna assembly includes an elongated antenna body and a microstrip line radiating assembly, one end of the antenna body being connectable to a millimeter-wave circuit capable of generating millimeter waves, and the microstrip line radiating assembly comprising multiple intermediate microstrip line radiating elements spaced apart in the middle section of the antenna body, and an end microstrip line radiating element located at the tail end of the antenna body, wherein the area of ​​the intermediate microstrip line radiating elements gradually increases from one end close to the millimeter-wave circuit toward the other end, so that the distribution of the radiated energy of each intermediate microstrip line radiating element approaches an average.

Description

Technical Field

[0001] This invention relates to a uniformly distributed radiation energy structure for millimeter-wave antennas, and more particularly to an antenna structure with better gain that can effectively improve the range of millimeter-wave radiation. Background Technology

[0002] As consumers place increasing emphasis on vehicle safety and related technologies mature, various automotive collision avoidance detection devices that can detect the dynamic conditions around a vehicle (such as the relative position, speed, and angle of vehicles, pedestrians, or other obstacles) to assist driving and prevent collisions are becoming increasingly widespread. Currently, the technologies used in commonly used collision avoidance detection devices can be roughly categorized as follows:

[0003] Ultrasonic waves: This is a mechanism that uses ultrasonic waves to measure the distance to an object. An ultrasonic sensor transmits and receives ultrasonic pulse waves through a transducer. This type of ultrasonic sensor can be calibrated based on changes in parameters such as temperature and voltage at startup or before each measurement range, and has a certain degree of accuracy. However, in use, because very small objects are difficult to effectively reflect ultrasonic waves, objects that are too small may not reflect enough ultrasonic waves to meet the detection requirements of the ultrasonic sensor, thus limiting its application.

[0004] Infrared: It uses the principle of light reflection for ranging. An infrared LED emits light, which is received and measured by another infrared receiver to determine the distance. However, infrared ranging has a small angle and lacks overall accuracy. Since the basic principle of detection is the reflection of light, it will seriously affect the detection results when used on surfaces with poor reflectivity (such as dark surfaces), resulting in application limitations.

[0005] Laser: A laser beam is emitted by a transmitter and the time (T1) is recorded. After the laser beam hits an object and reflects back, the time it takes for the sensor to receive the returned light is (T2). Assuming the speed of the laser beam in the air is V, the distance between the sensor and the object being measured can be calculated as: S = V * (T2 - T1) / 2. However, when using a laser device, if the surface of the transmitter is contaminated with water, dust, or other impurities, the laser light will be reflected back, generating false signals. In addition, the measurement accuracy of laser ranging is relatively poor, which are its disadvantages.

[0006] Millimeter waves: These electromagnetic waves have wavelengths between 1mm and 10mm (frequency range of 30GHz to 300GHz). The time difference between transmission and reception is measured, and the distance can be calculated. For long-range detection in vehicles, the 77GHz millimeter wave band is more suitable. Currently, the millimeter wave band used in vehicle surround radar is around 24GHz. Since millimeter waves have the longest wavelength, they are less affected by environmental climate and are most suitable for long-range detection.

[0007] Traditionally used in millimeter-wave devices, antenna structures for transmitting or receiving millimeter waves are as shown in Figure 1. The structure of the millimeter-wave antenna B can be directly etched onto the circuit board C, and includes two parts: a transmitting array antenna B1 composed of multiple comb-shaped antenna components 2, and a receiving array antenna B2. Figure 1 In the illustrated embodiment, the transmitting array antenna B1 consists of three comb antenna components 2, while the receiving array antenna B2 consists of four comb antenna components 2 (the comb antenna components 2 located on both sides of the receiving array antenna B2 serve an isolation function and do not transmit millimeter waves). In practical applications, the number of these comb antenna components 2 can be adjusted according to the millimeter wave transmission intensity and receiving sensitivity to meet different requirements.

[0008] The aforementioned conventional comb antenna assembly 2 structure is mainly composed of multiple microstrip line radiating elements 22 connected in series. Each microstrip line radiating element 22 is a rectangular (or square) structure of a fixed size, and they are arranged equally spaced and facing forward on a strip-shaped antenna body 21, thereby forming a comb antenna assembly 2 composed of a series-feed architecture. If this series-feed architecture comb antenna assembly 2 is applied to the transmitting array antenna B1 in the state of transmitting millimeter waves, the millimeter wave energy output by the default millimeter wave circuit C1 on the circuit board C is first passed through the comb. The antenna assembly 2 is fed into the head end (the end closest to the millimeter-wave circuit C1). When it passes the first microstrip line radiating element 22 (the one closest to the millimeter-wave circuit C1), it radiates a portion of the energy outward. The remaining energy continues to be fed along the antenna body 21 toward the tail end (the end away from the millimeter-wave circuit C1), and is radiated outward by each of the intermediate microstrip line radiating elements 22 (a small portion is lost during transmission) until the last microstrip line radiating element 22 radiates all the remaining energy.

[0009] As can be seen from the above, during the process of millimeter-wave energy being emitted outward through the comb antenna assembly 2, the energy radiated outward by each microstrip line radiating element 22 in the comb antenna assembly 2 is not the same. Based on the premise that the area of ​​each microstrip line radiating element 22 is proportional to the efficiency of the outward radiated energy, since each microstrip line radiating element 22 of this comb antenna assembly 2 has the same area, shape and arrangement, in practical applications, when the millimeter wave output from the millimeter-wave circuit C1 is introduced into the antenna body 21, it has the maximum energy, so the microstrip line radiating element 22 closest to the millimeter-wave circuit C1 will radiate more energy and bear a larger load. As the millimeter-wave energy is radiated outward by the microstrip line radiating element 22 one by one and gradually attenuates, the microstrip line radiating element 22 further away from the millimeter-wave circuit C1 will gradually radiate less energy and bear a smaller load. Thus, in the state of uneven energy distribution of each microstrip line radiating element 22, the overall efficiency of the comb antenna assembly 2 in radiating outward energy will be seriously affected.

[0010] Conversely, if this comb antenna assembly 2 is applied to the receiving array antenna B2 in the state of receiving millimeter waves, there will also be uneven distribution of received induced radiation energy.

[0011] In view of the aforementioned shortcomings of conventional millimeter-wave antenna structures, the inventors researched ways to improve these shortcomings, and finally the present invention came into being. Summary of the Invention

[0012] The main objective of this invention is to provide a uniformly distributed radiated energy structure for a millimeter-wave antenna, comprising at least one comb-shaped antenna assembly. The comb-shaped antenna assembly has an elongated antenna body and a microstrip line radiating assembly disposed on the antenna body. One end of the antenna body is connected to a millimeter-wave circuit capable of generating millimeter waves. The microstrip line radiating assembly consists of a plurality of intermediate microstrip line radiating units spaced apart in the middle section of the antenna body and an end microstrip line radiating unit disposed at the end of the antenna body away from the millimeter-wave circuit. These intermediate microstrip line radiating units each have different area sizes, and their area sizes are arranged in a manner that gradually increases from the intermediate microstrip line radiating units disposed at the end closest to the millimeter-wave circuit towards the other end, thereby making the radiated energy of each intermediate microstrip line radiating unit approach a uniformly distributed state, thereby improving the overall gain of the comb-shaped antenna assembly.

[0013] Another objective of this invention is to provide a uniformly distributed radiated energy structure for a millimeter-wave antenna, wherein each intermediate microstrip line radiating element is rectangular in shape, and the aspect ratio of the rectangle is in the range of 1.2 to 1.3:1, so that the resonant point of these intermediate microstrip line radiating elements can be maintained at a position close to 76.5 GHz, and the size ratio of two adjacent, gradually increasing intermediate microstrip line radiating elements is set in the range of 1.1 to 1.2:1, so as to radiate millimeter-wave energy outward more efficiently.

[0014] Another objective of the present invention is to provide a uniformly distributed radiated energy structure for a millimeter-wave antenna, wherein each intermediate microstrip line radiating element and the terminal microstrip line radiating element are arranged at an oblique angle on the antenna body, thereby reducing the effect of cross-directional interference; and the portion where the terminal microstrip line radiating element connects to the antenna body has a rectangular notch, which can reduce the reflection number of the terminal microstrip line radiating element.

[0015] To achieve the above objectives and effects, the technical means implemented by the present invention include: at least one comb antenna assembly, the comb antenna assembly having an elongated antenna body and a microstrip line radiating assembly disposed on the antenna body, one end of the antenna body being connected to a millimeter-wave circuit capable of generating millimeter waves; the microstrip line radiating assembly is composed of a plurality of intermediate microstrip line radiating units arranged at intervals in the middle section of the antenna body, and an end microstrip line radiating unit disposed at the end of the antenna body away from the millimeter-wave circuit, and the area of ​​the antenna body relative to the intermediate microstrip line radiating unit at the end away from the millimeter-wave circuit is not less than the area of ​​the intermediate microstrip line radiating unit relative to the end closer to the millimeter-wave circuit.

[0016] According to the above structure, the arrangement of these intermediate microstrip line radiating units is such that the area of ​​the intermediate microstrip line radiating units located closer to the millimeter-wave circuit is relatively smaller than the area of ​​the intermediate microstrip line radiating units located farther away from the millimeter-wave circuit.

[0017] According to the above structure, at least some of the adjacent intermediate microstrip line radiating units have the same area.

[0018] According to the above structure, the shape of each intermediate microstrip line radiating unit and the end microstrip line radiating unit is selected from one of the shapes such as rectangle, polygon and ellipse.

[0019] According to the above structure, the intermediate microstrip line radiating units are rectangular, and their length to width ratio is 1.2 to 1.3:1.

[0020] According to the above structure, the area ratio of the two adjacent, gradually increasing intermediate microstrip line radiating units is 1.1 to 1.2:1.

[0021] According to the above structure, the shape of the terminal microstrip line radiating unit is square.

[0022] According to the above structure, the part where the end microstrip line radiating element is connected to the antenna body has a rectangular notch.

[0023] According to the above structure, each intermediate microstrip line radiating element and the terminal microstrip line radiating element are arranged at intervals on the antenna body with the same direction and skew angle.

[0024] According to the above structure, the skew angle between each intermediate microstrip line radiating element and the terminal microstrip line radiating element and the antenna body is 45 degrees.

[0025] According to the above structure, each intermediate microstrip line radiating element is connected to the antenna body at its upper end corner. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of an existing millimeter-wave antenna;

[0027] Figure 2 This is a schematic diagram of the first embodiment of the uniform distribution structure of the millimeter-wave antenna of the present invention;

[0028] Figure 3 yes Figure 2 A partially enlarged schematic diagram of the intermediate microstrip line radiating unit;

[0029] Figure 4 yes Figure 2 A partially enlarged schematic diagram of the terminal microstrip line radiating unit;

[0030] Figure 5 This is a schematic diagram of the second embodiment of the uniform distribution structure of the millimeter-wave antenna of the present invention;

[0031] Figure 6 This is a schematic diagram of the third embodiment of the uniform distribution structure of the millimeter-wave antenna of the present invention;

[0032] In the diagram: 1, 10, 100, 2 comb antenna elements

[0033] 11, 21 antenna body

[0034] 111 Bending section

[0035] 12, 120, 1200 microstrip radiating components

[0036] 121, 122, 123 Intermediate microstrip line radiating units

[0037] 124 terminal microstrip line radiating units

[0038] 1241 gap

[0039] 22 microstrip line radiating units

[0040] A, A0, A00, B millimeter-wave antennas

[0041] A1, A10, A100, B1 transmitting array antennas

[0042] A2, A20, A200, B2 receiver array antennas

[0043] C circuit board

[0044] C1 millimeter-wave circuit

[0045] L121, L122 long side length

[0046] Short side lengths of W121 and W122

[0047] Y-interval distance. Detailed Implementation

[0048] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0049] like Figure 2 As shown, the structure of the millimeter-wave antenna A in Embodiment 1 of the present invention includes: a transmitting array antenna A1 composed of at least one comb antenna component 1 and / or a receiving array antenna A2 composed of at least one comb antenna component 1. In this embodiment, the transmitting array antenna A1 is composed of three comb antenna components 1, and the receiving array antenna A2 is composed of four comb antenna components 1. In practical applications, the transmitting array antenna A1 and / or the receiving array antenna A2 can be adjusted according to the required millimeter-wave transmission strength and receiving sensitivity. The number of each comb antenna assembly 1; wherein each comb antenna assembly 1 has a strip-shaped antenna body 11 and a microstrip line radiating assembly 12 disposed on the antenna body 11. The antenna body 11 is connected at one end to a millimeter-wave circuit C1 on a circuit board C. The microstrip line radiating assembly 12 is composed of a plurality of intermediate microstrip line radiating units 121, 122, and 123 arranged sequentially at intervals in the middle section of the antenna body 11, and an end microstrip line radiating unit 124 disposed at the end of the antenna body 11 away from the millimeter-wave circuit C1.

[0050] In this embodiment, the intermediate microstrip line radiating units 121, 122, and 123 have different area sizes, and their arrangement is such that the area of ​​the intermediate microstrip line radiating unit 121 located closer to one end of the millimeter-wave circuit C1 is set to be smaller, while the areas of the intermediate microstrip line radiating units 122, 123, etc., located gradually away from the millimeter-wave circuit C1 and toward the other end are set to gradually increase. The shape of each intermediate microstrip line radiating unit 121, 122, 123 and the terminal microstrip line radiating unit 124 can be rectangular, polygonal, or elliptical, etc.

[0051] Please refer to Figure 3, which discloses a preferred embodiment of the comb antenna assembly 1. The intermediate microstrip line radiating element 121 has a rectangular structure with a long side length L121 and a short side length W121. When the ratio of the long side length L121 to the short side length W121 is 1.2 to 1.3:1, the resonant point of the intermediate microstrip line radiating element 121 remains at a position close to 76.5 GHz. The adjacent intermediate microstrip line radiating element 122 at the next next position is also a similar rectangle. The structure has a fixed interval Y, with a long side length of L122 and a short side length of W122. The ratio of the long side length L122 to the short side length W122 is 1.2 to 1.3:1. At the same time, the ratio of the area of ​​the microstrip line radiating unit 122 at the next position (long side length L122 * short side length W122) to the area of ​​the original position microstrip line radiating unit 121 (long side length L121 * short side length W121) is 1.1 to 1.2:1.

[0052] By analogy, the intermediate microstrip line radiating elements 121, 122, and 123 can each be rectangular in shape, with their length-to-width ratio limited to 1.2–1.3:1. The area ratio of two adjacent, gradually increasing intermediate microstrip line radiating elements is limited to 1.1–1.2:1, and they have a fixed spacing Y. With this design of gradually increasing area outwards, when the millimeter-wave energy output by the millimeter-wave circuit C1 is transmitted to the intermediate microstrip line radiating element 121 closest to the millimeter-wave circuit C1 (at which point the millimeter-wave energy is strongest and the radiating area is smallest), after a portion of the energy is radiated outwards by the intermediate microstrip line radiating element 121, the remaining energy continues to be fed along the antenna body 21 towards the next intermediate microstrip line radiating element 122 (at which point the millimeter-wave energy is second strongest and the radiating area is smallest). By using a slightly larger area, the intermediate microstrip line radiating element 122 at the next position can utilize a larger radiating area to compensate for the attenuation of the millimeter-wave energy. This allows the energy radiated outward by the intermediate microstrip line radiating element 122 at the next position to approach the energy radiated outward by the intermediate microstrip line radiating element 121 at the original position. Similarly, after the intermediate microstrip line radiating element 122 at the next position radiates energy, the remaining energy is radiated outward by the intermediate microstrip line radiating element 123 at the next next position. By utilizing the larger radiating area of ​​the intermediate microstrip line radiating element 123 at the next next position to compensate for the further attenuation of the millimeter-wave energy, the radiated energy of the intermediate microstrip line radiating elements 121, 122, and 123 at each position can approach a state of even distribution, thereby improving the overall gain of the comb antenna assembly 1.

[0053] In practical applications, the intermediate microstrip radiating elements 121, 122, and 123 can be connected to the antenna body 11 by only their upper corners, and the intermediate microstrip radiating elements 121, 122, and 123 can be arranged and connected at the same skew angle in the same direction to reduce the effect of cross-directional interference. The skew angle shown in the figure is 45 degrees.

[0054] Please refer to Figure 4, which discloses another preferred embodiment of the comb antenna assembly 1. The terminal microstrip line radiating element 124 is rectangular (square), and the portion where the terminal microstrip line radiating element 124 connects to the antenna body 11 has a rectangular (square) notch 1241. The end of the antenna body 11 passes through the center of the notch 1241 and is then connected to the portion of the terminal microstrip line radiating element 124 near the center. The design of feeding in from the periphery through the notch 1241 can reduce the reflection number of the terminal microstrip line radiating element 124. Therefore, when the remaining energy after the middle microstrip line radiating elements 121, 122, and 123 radiate energy outwards is transmitted to the terminal microstrip line radiating element 124 via the antenna body 11, the remaining energy can be completely radiated outwards by the uniform propagation and diffusion of the terminal microstrip line radiating element 124 from the portion near the center, thereby further improving the overall gain.

[0055] In practical applications, the antenna body 11 may have a bent portion 111 at one end near the end microstrip line radiating unit 124, so that the end microstrip line radiating unit 124 can be arranged at the same skew angle as the aforementioned intermediate microstrip line radiating units 121, 122, and 123 via the bent portion 111, so as to further reduce the opposite interference.

[0056] like Figure 5 As shown, the structure of the millimeter-wave antenna A0 in Embodiment 2 of the present invention includes: a transmitting array antenna A10 composed of at least one comb antenna assembly 10 and / or a receiving array antenna A20 composed of at least one comb antenna assembly 10. In this embodiment, each comb antenna assembly 10 has a long strip-shaped antenna body 11 and a microstrip line radiating assembly 120 disposed on the antenna body 11. The antenna body 11 is connected at one end to a millimeter-wave circuit C1 on a circuit board C. The microstrip line radiating assembly 120 is composed of a plurality of intermediate microstrip line radiating units 121, 122, and 123 arranged sequentially at intervals in the middle section of the antenna body 11, and an end microstrip line radiating unit 124 disposed at the end of the antenna body 11 away from the millimeter-wave circuit C1.

[0057] The difference between the comb antenna assembly 10 of the second embodiment and the comb antenna assembly 1 of the first embodiment is that: each intermediate microstrip line radiating element 121, 122, and 123 in the microstrip line radiating assembly 120 has at least partially the same area; Figure 5 In the illustrated embodiment, the microstrip line radiating assembly 120 has two adjacent intermediate microstrip line radiating units 121 with the same minimum area closest to the millimeter-wave circuit C1, an intermediate microstrip line radiating unit 123 with the largest area located on the antenna body 11 at the position furthest from the millimeter-wave circuit C1, and two adjacent intermediate microstrip line radiating units 122 with the same second largest area located on the antenna body 11 between the minimum area intermediate microstrip line radiating unit 121 and the maximum area intermediate microstrip line radiating unit 123. This forms another comb antenna assembly 10 combination structure that conforms to the arrangement of intermediate microstrip line radiating units with gradually increasing or decreasing area.

[0058] like Figure 6 As shown, the structure of the millimeter-wave antenna A00 in Embodiment 3 of the present invention includes: a transmitting array antenna A100 composed of at least one comb antenna assembly 100 and / or a receiving array antenna A200 composed of at least one comb antenna assembly 100. In this embodiment, each comb antenna assembly 100 has a long strip-shaped antenna body 11 and a microstrip line radiating assembly 1200 disposed on the antenna body 11. The antenna body 11 is connected at one end to a millimeter-wave circuit C1 on a circuit board C. The microstrip line radiating assembly 1200 is composed of a plurality of intermediate microstrip line radiating units 121, 122, and 123 arranged sequentially at intervals in the middle section of the antenna body 11, and an end microstrip line radiating unit 124 disposed at the end of the antenna body 11 away from the millimeter-wave circuit C1.

[0059] Compared with the comb antenna assembly 1 of the first embodiment, the comb antenna assembly 100 of the third embodiment differs in that: the intermediate microstrip line radiating units 121, 122, 123 and the terminal microstrip line radiating unit 124 of the microstrip line radiating assembly 1200 are arranged on the antenna body 11 at intervals with a tilt angle of less than (or greater than) 45 degrees, thus forming another comb antenna assembly 100 combination structure with similar functions.

[0060] In summary, the uniform distribution structure of the millimeter-wave antenna of the present invention can indeed increase the millimeter-wave operating distance and improve anti-interference capability by enhancing the gain of each comb antenna component.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A uniformly distributed radiated energy structure for a millimeter-wave antenna, characterized in that, The antenna assembly includes at least one comb-shaped antenna component. The comb-shaped antenna component has an elongated antenna body and a microstrip line radiating component disposed on the antenna body. One end of the antenna body is connected to a millimeter-wave circuit capable of generating millimeter waves. The microstrip line radiating component consists of multiple intermediate microstrip line radiating elements spaced apart in the middle section of the antenna body, and terminal microstrip line radiating elements disposed at the end of the antenna body furthest from the millimeter-wave circuit. The area of ​​the intermediate microstrip line radiating elements relative to the end of the antenna body furthest from the millimeter-wave circuit is not less than the area of ​​the intermediate microstrip line radiating elements relative to the end closest to the millimeter-wave circuit. The arrangement is such that the area of ​​the intermediate microstrip line radiating element located closer to the millimeter-wave circuit is relatively smaller than the area of ​​the intermediate microstrip line radiating element located farther away from the millimeter-wave circuit. The intermediate microstrip line radiating elements are all rectangular, and their length-to-width ratio is 1.2~1.3:

1. The area ratio of two adjacent, gradually increasing intermediate microstrip line radiating elements is 1.1~1.2:

1. The intermediate microstrip line radiating elements and the terminal microstrip line radiating elements are arranged on the antenna body at intervals with the same direction and skew angle. The skew angle between the intermediate microstrip line radiating elements and the terminal microstrip line radiating elements and the antenna body is 45 degrees.

2. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 1, characterized in that, Locally adjacent intermediate microstrip line radiating units have the same area.

3. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 1 or 2, characterized in that, The shapes of the intermediate microstrip line radiating unit and the terminal microstrip line radiating unit are selected from rectangles, polygons, or ellipses.

4. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 3, characterized in that, The shape of the terminal microstrip line radiating unit is square.

5. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 1 or 3, characterized in that, The portion of the terminal microstrip line radiating element that connects to the antenna body has a rectangular notch.

6. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 1, characterized in that, The portion of the terminal microstrip line radiating element that connects to the antenna body has a rectangular notch.

7. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 1, characterized in that, The intermediate microstrip line radiating elements and the terminal microstrip line radiating elements are arranged on the antenna body at intervals with the same direction and skew angle.

8. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 7, characterized in that, The skew angle between the intermediate microstrip radiating element and the terminal microstrip radiating element and the antenna body is 45 degrees.

9. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 1, characterized in that, The intermediate microstrip line radiating elements are each connected to the antenna body at their upper corners.

10. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 7, characterized in that, The intermediate microstrip line radiating elements are each connected to the antenna body at their upper corners.

11. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 1, characterized in that, The intermediate microstrip line radiating elements are each connected to the antenna body at their upper corners.

12. The uniformly distributed radiation energy structure of a millimeter-wave antenna as described in claim 9, characterized in that, The intermediate microstrip line radiating elements are each connected to the antenna body at their upper corners.

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