A Miniaturized Conformal Microstrip Array Antenna for Human Brain Microwave Imaging and Its Design Method

Abstract

The present invention discloses a miniaturized conformal microstrip array antenna for human brain microwave imaging and its design method, which relates to the technical field of microstrip antennas and includes: a top dielectric block, a metal radiation patch, and a substrate dielectric block arranged from top to bottom; a metal through hole is provided on the substrate dielectric block, and the metal through hole is used to place a feeding probe; the antenna is applied to a brain microwave imaging system. The present invention is provided with a top dielectric block made of a high dielectric constant material, which effectively solves the problem of impedance mismatch when a microstrip patch antenna is applied to human brain imaging, realizes the miniaturization of the antenna unit, and as a conformal array antenna, it can well adapt to the brain sizes of different patients, and has the characteristics of miniaturization, low profile, high front-to-back ratio, stable radiation pattern, and light weight, and can be effectively applied to a portable brain microwave detection and imaging system.

Description

Technical Field

[0001] The present invention relates to the technical field of microstrip antennas, and more particularly to a miniaturized conformal microstrip array antenna for human brain microwave imaging and a design method thereof. Background Art

[0002] The microwave detection device for stroke mainly includes a microwave signal source, a transceiver antenna array, a switch matrix circuit for controlling the transceiver antenna, a data acquisition circuit, and a microwave data processing and analysis system. The transceiver antenna array is attached to a wearable device. The microwave signal source generates a swept-frequency signal of a large number of frequency points under the control of a host computer and transmits it through the antenna. The microwave signal acquisition module acquires and saves the electric field received by the antenna and imports it into the microwave signal processing module, and then achieves the purpose of stroke detection and blood clot localization by performing inverse imaging on the collected data. When using microwave technology for human brain detection and imaging, there are generally two methods: one is to place the antenna at a certain distance from the human tissue, and the other is to place the antenna close to the human tissue. For the first method, when the incident microwave signal touches the skin surface, it will be backward reflected due to the huge dielectric constant difference, which will cause more than 50% energy loss, increase the antenna back lobe, and the distance between the antenna and the human body will also cause additional transmission loss; in addition, due to the existence of surface waves on the human body, the actual energy penetrating into the human body will be lower. Therefore, in order to reduce the energy loss caused by reflection, it is of great significance to design a conformal array antenna close to the human tissue for human brain microwave detection and imaging.

[0003] For the antenna design in the human brain microwave imaging system, it is still a major problem at present. Human tissues (skin, muscle, tendon, bone, etc.) have a large dielectric constant (about 40), which is much larger than the dielectric constant of the substrate dielectric block (about 2 - 4). This huge dielectric constant difference brings great difficulties to the antenna design, especially the impedance matching problem of the antenna will be a great challenge. On the other hand, when imaging the human brain, the head circumference sizes of patients are different, and to avoid additional energy reflection, it is necessary to ensure that the antenna is as close as possible to the human tissue, and it is difficult for a planar antenna to achieve this function.

[0004] Microstrip patch antennas have been widely used due to their advantages such as low profile, lightweight, low cost, easy processing and manufacturing, and conformability. For traditional back-fed microstrip patch antennas, when used in air, it is easy to achieve impedance matching by simply changing the position of the feeding point and the size of the non-radiating edge. However, when the antenna is placed close to the human brain, the external medium of the antenna is human tissue with a very high dielectric constant, which makes it very difficult for ordinary microstrip patch antennas to achieve impedance matching: the huge difference in dielectric constants will make its impedance at a very small value, far less than 50 ohms in actual engineering. Although the impedance can be increased by moving the feeding probe position towards the patch edge or reducing the width of the antenna, under the condition that the external medium is the human brain with a high dielectric constant, the increased impedance is very small and still far from the standard impedance value of 50 ohms. In addition, the large difference in dielectric constants is likely to excite a surface wave layer on the surface of the microstrip patch antenna, thus reducing the radiation efficiency of the antenna.

[0005] In addition, in the prior art, the techniques related to the size of the antenna for brain imaging are as follows:

[0006] (1) B.J. Mohammed, A.M. Abbosh, S. Mustafa and D. Ireland, “Microwave System for Head Imaging,” IEEE Transactions on Instrumentation and Measurement, vol. 63, no. 1, pp. 117 - 123, Jan. 2014; its size is 90*95 mm.

[0007] (2) A.T. Mobashsher, A.M. Abbosh and Y. Wang, “Microwave System to Detect Traumatic Brain Injuries Using Compact Unidirectional Antenna and Wideband Transceiver With Verification on Realistic Head Phantom,” IEEE Transactions on Microwave Theory and Techniques, vol. 62, no. 9, pp. 1826 - 1836, Sept. 2014; its size is: 70 mm * 30 mm.

[0008] (3) A. T. Mobashsher and A. M. Abbosh, “Performance of Directional and Omnidirectional Antennas in Wideband Head Imaging,” IEEE Antennas and Wireless Propagation Letters, vol. 15, pp. 1618 - 1621, 2016; its dimensions are: 80mm * 45mm.

[0009] (4) A. T. Mobashsher and A. M. Abbosh, “Compact 3-D Slot-Loaded Folded Dipole Antenna With Unidirectional Radiation and Low Impulse Distortion for Head Imaging Applications,” IEEE Transactions on Antennas and Propagation, vol. 64, no. 7, pp. 3245 - 3250, July 2016; its dimensions are: 80mm * 20mm.

[0010] The frequency band used in the microwave detection technology for stroke is generally relatively low, which can better reduce the attenuation amplitude of the signal in the human brain. Moreover, the more the number of transceiver antennas, the more accurate the detection imaging effect. The lower the frequency band, the larger the antenna size. Therefore, the current technology cannot achieve miniaturization of the antenna size while maintaining the imaging effect, and it is rather difficult to truly achieve a low-frequency miniaturized antenna.

[0011] How to design a miniaturized conformal microstrip array antenna for human brain microwave imaging and its design method to solve the impedance mismatch when microstrip patch antennas are applied to human brain imaging, achieve miniaturization of antenna elements, and well adapt to the brain sizes of different patients is an urgent problem that those skilled in the art need to solve. Summary of the Invention

[0012] In view of this, the present invention provides a miniaturized conformal microstrip array antenna for human brain microwave imaging and its design method, which solves the impedance mismatch when microstrip patch antennas are applied to human brain imaging, realizes miniaturization of antenna elements, and well adapts to the brain sizes of different patients.

[0013] To achieve the above object, the present invention adopts the following technical solution: A miniaturized conformal microstrip array antenna for human brain microwave imaging, comprising: a plurality of antenna elements;

[0014] The antenna unit includes a top dielectric block, a metal radiation patch, and a bottom dielectric block arranged from top to bottom;

[0015] A metal through-hole is formed on the bottom dielectric block, and the metal through-hole is used to place a feeding probe;

[0016] The antenna is applied to a brain microwave imaging system.

[0017] Preferably, the feeding method adopts the coaxial back-feeding method.

[0018] Preferably, a first fixing through-hole is formed on the top dielectric block;

[0019] A second fixing through-hole is formed on the bottom dielectric block;

[0020] The first fixing through-hole and the second fixing through-hole are communicated with each other; they are used for fixing during use.

[0021] Preferably, the first fixing through-hole is formed at the four corners of the top dielectric block; or the second fixing through-hole is formed at the four corners of the bottom dielectric block.

[0022] Preferably, the antenna units are arranged circumferentially at a certain angle and are attached to the object to be measured with different sizes through the top dielectric block.

[0023] Preferably, the antenna unit further includes a metal ground plane, and the metal ground plane is arranged at the bottom of the bottom dielectric block.

[0024] Preferably, the dielectric constant of the top dielectric block is less than the dielectric constant of the object to be measured.

[0025] Preferably, a design method for a miniaturized conformal microstrip array antenna for human brain microwave imaging includes:

[0026] Adding a dielectric block as a top cover on the metal radiation patch on the basis of a microstrip patch antenna to form an antenna unit;

[0027] Performing conformal processing on the antenna unit.

[0028] Preferably, performing conformal processing on the antenna unit includes:

[0029] Initializing the radius of the conformal object to be measured, using cylinders with different radii to simulate objects to be measured with different sizes, and setting the cylinder radius in the range of 60 - 120 mm;

[0030] Optimizing the antenna parameters; making the antenna parameters have good electrical performance for different curvatures within a certain range through optimization;

[0031] Arranging multiple antenna units circumferentially at a certain angle.

[0032] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a miniaturized conformal microstrip array antenna for human brain microwave imaging and its design method, including: a top dielectric block, a metal radiation patch, and a substrate dielectric block arranged from top to bottom; a metal through hole is formed on the substrate dielectric block, and the metal through hole is used to place a feeding probe; the antenna is applied to a brain microwave imaging system. The present invention is provided with a top dielectric block made of a high dielectric constant material, which effectively solves the problem of impedance mismatch when a microstrip patch antenna is applied to human brain imaging, realizes the miniaturization of the antenna unit, and as a conformal array antenna, it can well adapt to the brain sizes of different patients, and has the characteristics of miniaturization, low profile, high front-to-back ratio, stable radiation pattern, and light weight, and can be effectively applied to a portable brain microwave detection and imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0034] Figure 1 It is an application topology diagram of a miniaturized conformal microstrip array antenna for human brain microwave imaging provided by an embodiment of the present invention.

[0035] Figure 2 It is a top view of a miniaturized conformal microstrip array antenna for human brain microwave imaging provided by an embodiment of the present invention.

[0036] Figure 3 It is a side view (plane unfolded type) of a miniaturized conformal microstrip array antenna for human brain microwave imaging provided by an embodiment of the present invention.

[0037] Figure 4 It is an echo loss diagram of a conformal antenna unit provided by an embodiment of the present invention.

[0038] Figure 5 It is an input impedance diagram of a conformal antenna unit provided by an embodiment of the present invention.

[0039] Figure 6 It is a mutual coupling diagram of a conformal array antenna provided by an embodiment of the present invention.

[0040] Figure 7 It is a radiation pattern of a conformal array antenna provided by an embodiment of the present invention.

[0041] Among them, 1 - antenna unit, 2 - metal radiation patch, 3 - substrate dielectric block, 4 - metal through - hole, 5 - second fixed through - hole, 6 - first fixed through - hole, 7 - top substrate dielectric block. Detailed implementation manners

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] The embodiment of the present invention discloses a miniaturized conformal microstrip array antenna for human brain microwave imaging and its design method, including: a top substrate dielectric block, a metal radiation patch, and a substrate dielectric block arranged from top to bottom; a metal through - hole is provided on the substrate dielectric block, and the metal through - hole is used to place a feeding probe; the antenna is applied to a brain microwave imaging system. The present invention is provided with a top substrate dielectric block made of a high - dielectric - constant material, which effectively solves the problem of impedance mismatch when a microstrip patch antenna is applied to human brain imaging, realizes the miniaturization of the antenna unit, and as a conformal array antenna, can well adapt to the brain sizes of different patients, having the characteristics of miniaturization, low profile, high front - to - back ratio, stable radiation pattern, and light weight, and can be effectively applied to a portable brain microwave detection and imaging system.

[0044] In a specific embodiment of the present invention, a miniaturized conformal microstrip array antenna for human brain microwave imaging includes: a plurality of antenna units 1;

[0045] The antenna unit 1 includes a top substrate dielectric block 7, a metal radiation patch 2, and a substrate dielectric block 3 arranged from top to bottom; a metal through - hole 4 is provided on the substrate dielectric block 3, and the metal through - hole 4 is used to place a feeding probe; the antenna is applied to a brain microwave imaging system. As Figure 2 and Figure 3 shown. The feeding probe is connected to the metal radiation patch.

[0046] When designing an antenna, impedance is related not only to the size of the antenna itself but also to the dielectric constant of the external medium. When the external medium is air (the dielectric constant of air is 1), the electromagnetic wave is incident from an optically denser medium to an optically rarer medium, and it is easier to achieve matching; while when the external is human tissue with a relatively high dielectric constant, the huge difference in dielectric constant makes it impossible to match. In the embodiment of the present invention, a layer of top lining is covered on the surface of the metal radiation patch 2, which is equivalent to alleviating the huge difference in dielectric constant when the electromagnetic wave is incident from an optically rarer medium to an optically denser medium, reducing the equivalent dielectric constant and making it easier to match. The top substrate dielectric block 7 plays a transitional role, preventing the electromagnetic wave from directly incident into the human tissue with a larger difference.

[0047] Specifically, the feeding method adopts the coaxial line back-feeding method.

[0048] Specifically, the top dielectric block 7 is provided with a first fixing through hole 6; the substrate dielectric block 3 is provided with a second fixing through hole 5; the first fixing through hole 6 and the second fixing through hole 5 are communicated with each other and are used for fixing during use.

[0049] Specifically, the first fixing through holes 6 are opened at the four corners of the top dielectric block 7 ; or the second fixing through holes 5 are opened at the four corners of the substrate dielectric block 3 .

[0050] Specifically, the antenna units 1 are arranged circumferentially at a certain angle, and are attached to objects to be measured of different sizes through the top dielectric block.

[0051] Specifically, the dielectric constant of the substrate top dielectric block is smaller than the dielectric constant of the object to be measured.

[0052] Figure 1 The application topology diagram of a miniaturized conformal microstrip array antenna for microwave imaging of the human brain provided by an embodiment of the present invention is used in a microwave imaging system of the human brain; Figure 1 As shown, the object to be tested is a cylinder, and the antenna unit 1 is arranged on the cylindrical object to be tested at a certain angle. The cylindrical object to be tested is used to simulate the circumference of a human head, so that the electrical performance of the antenna on the surface of the human body can be better simulated. The frequency band to be simulated in the embodiment of the present invention is 1 GHz, and the initial radius value R of the cylindrical object to be tested for conformal 0 The range is set between 60-120mm (corresponding to the head size of different patients), which can be adjusted flexibly later. The array element spacing corresponds to a central angle θ of 30°, and the dielectric constant of human tissue ε r Set to 40.

[0053] Specifically, the antenna unit 1 further includes a metal ground plate, and the metal ground plate is arranged at the bottom of the substrate dielectric block 3 .

[0054] Figure 2 The planar unfolded top view provided by the embodiment of the present invention is as follows: Figure 2 As shown, a metal radiation patch 2 is printed on a piece of thickness h 2 =2mm substrate dielectric block 3, the dielectric material is Rogers6010, the length and width of the metal radiation patch 2 are L 2 =38.8mm and W 2 =16.7mm, the feeding method is coaxial backfeed, at a distance of L from the center of the patch 3 = 16mm, a metal through hole 4 is reserved for placing the feeding probe, and the radius of the metal through hole 4 is R 1= 0.6 mm; in addition, four second fixing through - holes 5 are provided at the four corners of the substrate dielectric block 3, and the radius of the second fixing through - hole 5 is R 2 = 1 mm; the second fixing through - holes are used for fixing.

[0055] Figure 3 This is a planar unfolded side view of a miniaturized conformal microstrip array antenna for human brain microwave imaging provided by an embodiment of the present invention. As Figure 3 shown in Figure 2 a piece of h 1 = 2 mm thick top substrate dielectric block 7 (made of Rogers 6010 material with a dielectric constant of 10) is loaded on the surface of the metal radiation patch. The length and width of the top substrate dielectric block 7 are equal to those of the substrate dielectric block 3; together with the substrate dielectric block 3 with a metal radiation patch and a ground printed on its lower surface, a complete antenna unit is formed. Since the metal radiation patch is very thin, only a thickness of more than ten micrometers, which can be ignored, the top substrate dielectric block 7 is directly covered on it. Four through - holes the same as those of the substrate dielectric block 3 are also left at the four corners of the top substrate dielectric block 7 for fixing during use. The overall size of the antenna is 46.56 mm × 20.04 mm × 4 mm (0.155λ 0 × 0.067λ 0 × 0.013λ 0 , where λ 0 is the free - space wavelength at 1 GHz frequency point).

[0056] Among them, as Figure 2 shown, 4 first fixing through - holes or second fixing through - holes are respectively provided, distributed in a rectangular shape, with a length of L 4 , and a width of W 3 . The length L 2 and width W 2 of the metal radiation patch are both smaller than the length L 1 and width W 1 of the substrate dielectric block, and the length L 2 and width W 2 of the metal radiation patch are smaller than the length L 4 and width W 3 of the first fixing through - holes or second fixing through - holes distributed in a rectangular shape.

[0057] Figure 4 Shown is the echo - loss diagram of the conformal antenna unit corresponding to different cylinder radii in an embodiment of the present invention. As Figure 4As shown, the return losses of the antennas are all in a relatively stable state, indicating that it has good adaptability to different patients when applied to human brain microwave detection imaging (the cylindrical radius corresponds to different head circumference sizes of the human brains to be detected). Taking a radius of 100 mm as an example, the region where the return loss of the antenna is below -10 dB at this time is 0.97 - 1.04 GHz, that is, the impedance bandwidth is 70 MHz and the relative bandwidth is 7%, and a good resonance effect is achieved near the frequency point of 1 GHz.

[0058] Figure 5 The following shows the input impedance diagram of the conformal antenna unit in the embodiment of the present invention. Taking a radius of 100 mm as an example, as Figure 5 shown, when the imaginary part is 0, the real part is approximately 50, that is, a good impedance matching effect is achieved, which also proves the good function of the dielectric loading in the embodiment of the present invention.

[0059] Figure 6 The following shows the mutual coupling diagram between adjacent antenna units in the conformal array at different radii in the embodiment of the present invention. To ensure the actual use effect, the mutual coupling value is generally required to be less than -10 dB. As Figure 6 shown, when the radius is 60 mm (the minimum radius value), the mutual coupling strength between two adjacent conformal antenna units is -16 dB, weaker than the minimum mutual coupling value; the larger the radius, the farther the distance between adjacent antenna units. When the radius is 120 mm, the mutual coupling strength between two adjacent conformal antenna units is -25 dB, much weaker than the minimum mutual coupling value. Based on this analysis, the mutual coupling strength between the two closest conformal antenna units is much less than -10 dB, so the antenna mutual coupling in other cases (non-adjacent antenna units) can be ignored.

[0060] Figure 7 The following shows the radiation pattern between conformal antenna units at different radii in the embodiment of the present invention. Because in the application of human brain detection imaging based on microwaves, the antenna transmits and receives multiple signals, and the transmitting antenna number is sequentially switched to collect and analyze data. Therefore, in the embodiment of the present invention, only the radiation pattern of a single array element in the array is considered. As Figure 7 shown, when the cylindrical radius increases from 60 mm to 120 mm, for the conformal antenna units in the array, a relatively symmetric and regular radiation pattern is shown, and the front-to-back ratio is greater than 6 dB.

[0061] Principle of the embodiment of the present invention: Microstrip patch antennas have been widely used due to their advantages such as low profile, light weight, and easy processing. And the characteristic that it has its own ground plane makes it less affected by the outside world during actual application. However, when it is close to a medium with a high dielectric constant such as the human brain, there will be a situation of very small impedance mismatch: When a microstrip patch antenna that is used in air and has achieved a 50-ohm impedance match is applied to human brain microwave detection and imaging, its impedance may drop sharply to only a few ohms or a dozen ohms. At this time, most of the energy of the antenna will be reflected back, affecting the effect of human brain microwave detection and imaging. The traditional microstrip antenna is to increase L 3 (that is, move the feed to the edge of the antenna) to increase the impedance. However, through simulation, it is found that even if this is done in a background with a high dielectric constant, its impedance is still much less than 50 ohms, so impedance matching cannot be achieved. Therefore, the embodiment of the present invention analyzes the mechanism of the microstrip antenna. After the energy radiates from the radiation patch, if it directly enters a medium with a high dielectric constant such as the human brain (the average dielectric constant of the human brain is about 40), the huge dielectric constant difference makes it difficult to achieve the effect of impedance matching (the equivalent dielectric constant is too large); Therefore, the embodiment of the present invention adds a top dielectric block with a lower dielectric constant than the human brain above the metal radiation patch. The dielectric constant of the top dielectric block can be set to be less than the average dielectric constant of the brain (ε 1 <ε r ); ε 1 represents the dielectric constant of the top dielectric block, and ε r represents the average dielectric constant of the brain, and ε r = 40. So that the electromagnetic wave radiates from the radiation patch and first passes through a medium with a small dielectric constant difference such as the top dielectric block and then is transmitted into the human brain. By adding the top dielectric block, it is easier to achieve the effect of impedance matching (reduce the equivalent dielectric constant).

[0062] The dielectric constant of the traditional microstrip antenna is usually set to 2 - 4. When using a microstrip antenna for human brain microwave detection, the dielectric constant difference is 36 - 38. The large dielectric constant difference is not conducive to achieving impedance matching; and when the dielectric constant of the traditional microstrip antenna is directly set to 10, at this time, the antenna size will be extremely thin (simulation results show that its patch width is smaller than a general coaxial feed SMA connector), which is not conducive to feeding and actual application in the human brain microwave image detection system.

[0063] Specifically, in the embodiments of the present invention, the dielectric constants of the substrate dielectric block and the top substrate dielectric block are both set to 10. Generally speaking, the higher the dielectric constant of the medium of a microstrip patch antenna, the smaller its size and the narrower its bandwidth. Considering the special application scenario of human brain microwave detection and imaging, a trade-off is made between bandwidth and impedance matching, and the dielectric constants of the substrate dielectric block and the top substrate dielectric block are both set to 10 as the optimal solution in the embodiments of the present invention, achieving the effect of antenna miniaturization, being convenient to carry, improving the accuracy and stability of imaging, and better adapting to the actual use environment of human brain imaging equipment; at the same time, the same dielectric constants of the substrate dielectric block and the top substrate dielectric block also make the antenna more convenient in the process of processing and manufacturing. Among them, if the dielectric constants of the substrate dielectric block and the top substrate dielectric block are less than 10, it will be difficult to achieve the impedance matching of the antenna and the size of the antenna will increase; if the dielectric constants of the substrate dielectric block and the top substrate dielectric block are greater than 10, the bandwidth will be narrower; therefore, considering the performance requirements of antenna bandwidth and impedance matching as a trade-off, the embodiments of the present invention preferably set the dielectric constants of the substrate dielectric block and the top substrate dielectric block to 10 both.

[0064] The embodiments of the present invention also provide a design method for a miniaturized conformal microstrip array antenna for human brain microwave imaging, including:

[0065] Adding a dielectric block as the top substrate to cover the metal radiation patch on the basis of the microstrip patch antenna to form an antenna unit;

[0066] Performing conformal processing on the antenna unit (i.e., bending with a certain curvature).

[0067] Specifically, performing conformal processing on the antenna unit includes:

[0068] Initializing the radius of the conformal object to be measured, and using cylinders with different radii to simulate objects to be measured with different sizes; the cylinder radius is set in the range of 60 - 120 mm;

[0069] Optimizing the antenna parameters; making its electrical performance better for different curvatures within a certain range by optimizing the antenna parameters;

[0070] Circumferentially arranging a plurality of antenna units at a certain angle; arranging them evenly in a circle according to the number of antenna units and the head circumference size of the object to be measured.

[0071] In the embodiment of the present invention, a pure dielectric block is added on the basis of a traditional microstrip patch antenna as a substrate covering the metal radiation patch. Using this method can effectively reduce the equivalent dielectric constant and thus improve the impedance mismatch problem caused by the large dielectric constant difference of human tissues. It can also suppress the surface waves excited by the large dielectric constant difference to ensure the radiation efficiency of the antenna; using a dielectric with a higher dielectric constant will obtain a better matching effect and realize the miniaturization of the antenna. The feeding method adopts the coaxial backfeeding method; for convenient fixation during use, a fixing through-hole can be opened at each of the four corners of the antenna; thus, the design of the planar antenna unit for the human brain microwave imaging system is completed. Next is the design of the conformal antenna array. The above antenna unit is conformally processed, and the radius of the conformal object to be measured is initialized to 100 mm (i.e., bent, and the conformal carrier is a cylinder with different radii to simulate the heads of patients with different sizes. According to statistics, the adult head circumference size is 54 - 58 cm. Therefore, in the embodiment of the present invention, the radius of the cylinder simulating the human head is set in the range of 60 - 120 mm), so that the substrate dielectric block of the antenna can better fit on the patient's brain and reduce the energy reflection caused by the gap between the planar antenna and the human body; by optimizing the antenna parameters, it has good electrical performance for different curvatures within a certain range (this certain range is the one simulating the human head circumference size, that is, the radius of the cylinder corresponding to the adult head circumference size (54 - 58 cm), and the degree of bending at this radius is the curvature); then it is arranged around the cylinder at a certain angle to simulate the data collection of the antenna arranged in a circle around the human brain for imaging detection.

[0072] Specifically, in the embodiment of the present invention, the antenna is designed using the commercial electromagnetic software HFSS and the antenna parameters are optimized; for example, between 1 and 2, if it is not known which value is the optimal solution, the parameter sweeping can be set through HFSS, such as starting from 1, with an interval of 0.1 until 2, and then observing which of these parameters is the optimal solution of the antenna to achieve the purpose of parameter optimization.

[0073] Therefore, the embodiment of the present invention adopts a miniaturized conformal microstrip array antenna for human brain microwave imaging and its design method with the above structure for the human brain microwave imaging system, which has the following beneficial effects:

[0074] (1) By adopting the method of dielectric covering to add a dielectric cap, the problem of impedance mismatch in the environment of the human brain with a high dielectric constant is solved; at the same time, due to the use of the high dielectric constant cap, the miniaturization of the conformal antenna element is realized, which is more convenient for the subsequent array formation. (2) The antenna is conformalized, which is easier to fit on the surface of human tissues, thus avoiding the energy reflection and leakage caused by the gap between the planar antenna and human tissues; in addition, by optimizing the antenna parameters, it can maintain good electrical performance parameters within a certain range of curvatures, so as to better adapt to patients with different head circumferences. (3) Since multiple antenna elements are arranged circumferentially at a certain angle, as Figure 1 shown, therefore, when the head circumference of the object to be measured is certain, the smaller the size of antenna element 1, the more antenna elements can be arranged circumferentially, and the denser the finally collected data, and the more accurate the judgment result; and in the miniaturized conformal array antenna, since the size of each antenna element is very small, the bending angle required for each antenna element will also be very small, which also ensures the electrical performance parameters of the antenna to a certain extent.

[0075] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0076] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A miniaturized conformal microstrip array antenna for microwave imaging of the human brain, characterized in that: include: A plurality of antenna units (1); The antenna unit (1) comprises a top dielectric block (7), a metal radiation patch (2) and a substrate dielectric block (3) arranged from top to bottom; The substrate dielectric block (3) is provided with a metal through hole (4), and the metal through hole (4) is used to place a feeding probe; The antenna is applied to a brain microwave imaging system; Performing conformal processing on the antenna unit; The dielectric constants of the substrate dielectric block and the top dielectric block are both set to 10; The top lining medium block (7) is provided with a first fixing through hole (6); The substrate dielectric block (3) is provided with a second fixing through hole (5); The first fixing through hole (6) and the second fixing through hole (5) are in communication with each other and are used for fixing during use.

2. A miniaturized conformal microstrip array antenna for microwave imaging of the human brain according to claim 1, characterized in that: The feeding method adopts the coaxial line back-feeding method.

3. A miniaturized conformal microstrip array antenna for microwave imaging of the human brain according to claim 2, characterized in that: The first fixing through holes (6) are opened at the four corners of the top dielectric block (7); or the second fixing through holes (5) are opened at the four corners of the substrate dielectric block (3).

4. The miniaturized conformal microstrip array antenna for microwave imaging of the human brain according to claim 1, characterized in that: The antenna units (1) are arranged circumferentially at a certain angle, and fit with objects to be measured of different sizes via the top dielectric block (7).

5. The miniaturized conformal microstrip array antenna for microwave imaging of the human brain according to claim 1, characterized in that: The antenna unit (1) also includes a metal ground plate, which is arranged at the bottom of the substrate dielectric block (3).

6. The miniaturized conformal microstrip array antenna for microwave imaging of the human brain according to claim 1, characterized in that: The dielectric constant of the substrate dielectric block is smaller than the dielectric constant of the object to be measured.

7. A design method for a miniaturized conformal microstrip array antenna for microwave imaging of the human brain, using the miniaturized conformal microstrip array antenna for microwave imaging of the human brain as claimed in any one of claims 1 to 6, characterized in that: include: A dielectric block is added on the basis of the microstrip patch antenna as a top cover to cover the metal radiation patch to form an antenna unit; The antenna unit is subjected to conformal processing.

8. The design method of a miniaturized conformal microstrip array antenna for microwave imaging of the human brain according to claim 7, characterized in that: Performing conformal processing on the antenna unit includes: Initialize the radius of the conformal object to be tested, and use cylinders with different radii to simulate objects of different sizes; Optimize antenna parameters; Multiple antenna units are arranged circumferentially at a certain angle.

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