TW201821015A - Microwave imaging system - Google Patents

Abstract

A microwave imaging system is provided, which includes a signal transmitting circuit, a signal receiving circuit and a signal processing and computing circuit. The signal transmitting circuit emits at least one microwave signal having at least one frequency toward an object-under-test, and the signal receiving circuit receives the microwave signal through the object-under-test or reflected by the object-under-test. The signal processing and computing circuit is configured to generate the microwave signals with different frequencies. The signal processing and computing circuit generates a detection image according to the microwave signal received by the signal receiving circuit. Each the transmitting antenna of the signal transmitting circuit and the receiving antenna of the signal receiving circuit is a planar metamaterial antenna respectively, and the planar metamaterial antenna includes a plurality of resonance units arranged regularly.

Description

Microwave imaging system

This invention relates to an imaging technique and, more particularly, to a microwave imaging system.

With the advancement of medical science, imaging devices that are currently used more commonly in medical imaging inspection include: X-ray imaging devices, digital imaging devices, and nuclear magnetic resonance imaging devices. Among them, the X-ray imaging device produces a 10-20% false negative of the detected image, so patients often have to go through a digital imaging device or an MRI device for further examination. However, the hardware cost of the digital imaging device and the magnetic resonance imaging device is relatively expensive, which in turn causes a burden on the patient.

Microwave imaging systems have been widely discussed in recent years. Microwave is Non-ionization Radiation, which is dose-free and safe, and is not easy to damage tissues or organs outside the target. Imaging the body composition with a microwave imaging system not only improves diagnostic flexibility and diagnostic accuracy, but its equipment is less expensive than X-ray or MRI instruments. Traditional microwave imaging systems mostly use a waveguide tube to structure the entire RF front-end circuit of the microwave imaging system to obtain sufficient semaphores for imaging. However, although the waveguide has the advantage of being able to withstand high power and extremely low loss, the size of the transmitting and receiving antenna in the form of a waveguide is quite large, making the overall volume of the conventional microwave imaging system very large. Injured patients often need to go to a specific medical facility to use the microwave imaging system for inspection. Medical personnel cannot immediately perform medical examinations on injured patients in emergency places through the microwave imaging system.

In view of the above, the present invention provides a microwave imaging system that transmits and receives microwave signals through a planar metamaterial antenna to reduce the volume of the microwave imaging system and improve portability under conditions of high antenna gain.

The invention provides a microwave imaging system comprising a signal transmitting circuit, a signal receiving circuit, and a signal processing and arithmetic circuit. The signal transmitting circuit emits at least one microwave signal having at least one frequency toward an object to be tested, and the signal receiving circuit receives the microwave signal penetrating the object to be tested and the microwave signal reflected by the object to be tested. The signal processing and operation circuit is coupled to the signal transmitting circuit and the signal receiving circuit for generating microwave signals having different frequencies. The signal processing and operation circuit generates a detection image of the object to be tested according to the microwave signal received by the signal receiving circuit. The transmitting antenna of the signal transmitting circuit and the receiving antenna of the signal receiving circuit are each a planar metamaterial antenna, and the planar metamaterial antenna includes a plurality of resonant units arranged periodically.

In an embodiment of the invention, the resonant unit is disposed on the first surface of the dielectric substrate, and each of the resonant units is a separate ring resonator.

In an embodiment of the invention, the split ring resonator described above includes an inner annular conductor and an outer annular conductor. The inner annular conductor has an inner radius and an inner ring opening, and the outer annular conductor has an outer ring opening and surrounds the inner annular conductor. The inner annular conductor and the outer annular conductor are coupled to each other at a coupling pitch.

In an embodiment of the invention, the line width of the inner annular conductor is the same as the line width of the outer annular conductor and is a predetermined width.

In an embodiment of the invention, the operating frequency bands of the receiving antenna and the transmitting antenna are determined according to a preset width, a coupling pitch, and an inner radius.

In an embodiment of the invention, the coupling pitch is the same as the preset width.

In an embodiment of the invention, the number of the resonant units is at least three.

In an embodiment of the invention, the dielectric substrate is selected from the group consisting of a germanium substrate, a gallium arsenide substrate, a ceramic substrate, a glass substrate, a glass fiber substrate, a hydrocarbon ceramic substrate, a Teflon substrate, and a Teflon glass fiber. One of the substrate and the Teflon ceramic substrate.

In an embodiment of the invention, the ground plane is disposed on the second surface of the dielectric substrate, and the resonant unit receives or transmits the microwave signal from the signal feed port via the at least one signal feed line on the first surface or the second surface. .

In an embodiment of the invention, the resonant unit is coupled to the signal feed port via a through hole in the dielectric substrate.

Based on the above, an embodiment of the present invention provides a microwave imaging system. By arranging a planar metamaterial antenna as a microwave transmitting antenna and a microwave receiving antenna, the microwave imaging system can construct an object to be tested by calculating a dielectric constant distribution of scattered field data at different microwave frequencies. Image and composition characteristics information. Thereby, the volume of the microwave imaging system can be reduced, thereby contributing to the expansion of the applicable environment of the microwave imaging system, so that emergency personnel can carry out effective treatment according to the image of the microwave imaging by carrying the microwave imaging system.

The above described features and advantages of the invention will be apparent from the following description.

In order to make the disclosure of the present disclosure more readily apparent, the following exemplary embodiments are set forth as examples of the disclosure. However, the present invention is not limited to the illustrated exemplary embodiments, and an appropriate combination is also allowed between the exemplary embodiments. In addition, wherever possible, the same elements, components, and steps in the drawings and embodiments are used to represent the same or similar components.

FIG. 1 is a schematic diagram of a system architecture of a microwave imaging system according to an embodiment of the invention. Referring to FIG. 1 , the microwave imaging system 10 of the present embodiment can acquire a tomographic image of the object to be tested 100 by means of microwave scanning, thereby presenting the composition of the object to be tested 100 by using an image. Specifically, the microwave imaging system 10 includes a signal transmitting circuit 110, a signal receiving circuit 120, a signal processing and arithmetic circuit 130, and a computer 140. In the present embodiment, the signal transmitting circuit 110 includes a transmitter 111 and a transmitting antenna 112, and the signal receiving circuit includes a receiver 121 and a receiving antenna 122. The transmitter 111 and the receiver 121 may include a mixer, a filter, a low noise amplifier, and other radio frequency circuit front end components, which are not limited by the present invention.

The microwave imaging system 10 firstly outputs a plurality of sets of microwave signals to the object 100 to be tested by the transmitting antenna 112, and then receives the related microwave signals through the receiving antenna 122 and reflected by the object 100 to be tested and the object to be tested 100. More specifically, the transmitter 111 can transmit multiple sets of drive signals to the transmit antenna 112, such that the transmit antenna 112 emits multiple sets of microwave signals corresponding to different frequencies. The microwave signal enters the object to be tested 100 along the propagation path, thereby penetrating the biological tissue in the object 100 to be tested. In this embodiment, the signal transmitting circuit 110 transmits at least one microwave signal SS1 having at least one frequency toward the object to be tested 100, and the signal receiving circuit 120 receives the microwave reflected by the object to be tested 100 and the object to be tested 100. Signal SS2.

The signal processing and computing circuit 130 is coupled to the signal transmitting circuit 110 and the signal receiving circuit 120 for controlling the operation of the signal transmitting circuit 110 and the signal receiving circuit 120 to generate microwave signals SS1 having different frequencies through the signal transmitting circuit 110. Thereafter, the signal receiving circuit 120 can transmit the scattered field data generated according to the received microwave signal SS2 to the signal processing and arithmetic circuit 130 of the back end for processing. Based on this, the signal processing and operation circuit 130 can generate a detection image of the object to be tested according to the microwave signal SS2 received by the signal receiving circuit 120.

in particular. The signal processing and operation circuit 130 can perform an operation according to the scattered field data provided by the signal receiving circuit 120 to obtain a dielectric coefficient associated with the object 100 to be tested. It should be specially noted that the biological tissue of the object to be tested 100 is a conductive medium of microwave signals, and different biological tissues have different electrical characteristics. Specifically, the electrical properties of the biological tissue of the object 100 to be tested can be defined by conductivity and dielectric constant. In addition, biological tissues have different electrical and dielectric coefficients for microwave signals of different frequencies. Therefore, the signal processing and operation circuit 130 can perform image restoration analysis according to the calculated dielectric coefficient, thereby generating a detection image of the object 100 to be tested. The signal processing and computing circuit 130 may include a hardware circuit and a memory having a logic operation capability, such as a microcontroller (MCU), etc., and the invention is not limited thereto.

In this embodiment, the computer 140 can be coupled to the signal processing and computing circuit 130, and the computer 140 can provide a display interface and a user control interface. In this way, the detected image of the object to be tested 100 can be displayed through the display interface of the computer, and the operator can control the entire microwave imaging system 10 through the user control interface provided by the computer 140. For example, the microwave imaging system 10 is controlled to begin scanning.

It is to be noted that, in this embodiment, the transmitting antenna 111 of the signal transmitting circuit 110 and the receiving antenna 121 of the signal receiving circuit 120 are each a planar metamaterial antenna, and the planar metamaterial antenna includes periodicity. A plurality of resonant units arranged. A metamaterial antenna is an antenna that uses a metamaterial to manipulate an antenna system to increase efficiency and signal gain. As with any other electromagnetic antenna, the purpose of a metamaterial antenna is to emit energy into free space. In this embodiment, the planar metamaterial antenna has closely arranged resonators.

2A and 2B are schematic diagrams showing the structure of a planar metamaterial antenna according to an embodiment of the invention. In the present exemplary embodiment, since the structure and operation principle of the transmitting antenna 112 and the receiving antenna 121 are substantially the same, the transmitting antenna 112 will be described first as follows.

Referring to FIGS. 2A and 2B, the transmitting antenna 112 includes a first surface S1 and a second surface S2. In this embodiment, the plurality of resonance units 112_1, 112_2, ..., 112_N, ..., 112_M are disposed on the first surface S1 of the dielectric substrate 112P, and the resonance units 112_1, 112_2, ..., 112_N, ..., 112_M are periodically arranged. On the first surface S1. The material of the resonance units 112_1, 112_2, ..., 112_N, ..., 112_M may be one of copper, silver, aluminum, titanium, tungsten or an alloy thereof, and the like, which is not limited in the present invention. The resonance units 112_1, 112_2, ..., 112_N, ..., 112_M can be constructed, for example, on the substrate 112P by a circuit printing technique. The present invention is not limited to the number of resonance units, and it is preferable to constitute the transmission antenna of the present invention with three or more resonance units.

The dielectric substrate 112P is selected from the group consisting of a germanium substrate, a gallium arsenide substrate, a ceramic substrate, a glass substrate, a glass fiber substrate, a hydrocarbon ceramic substrate, a Teflon substrate, a Teflon glass fiber substrate, and a Teflon ceramic substrate. The invention is not limited thereto. The ground plane 112G is disposed on the second surface S2 of the dielectric substrate 112P. The material of the ground plane 112G is, for example, one of copper, silver, aluminum, titanium, tungsten or alloy thereof, etc., and the present invention is not limited thereto, and the ground plane 112G can also be constructed on the substrate 112P through circuit printing technology.

In the present exemplary embodiment, each of the resonance units 112_1, 112_2, ..., 112_N, ..., 112_M is a separate ring resonator. FIG. 2C is a schematic structural diagram of a resonance unit according to an embodiment of the invention. In the present exemplary embodiment, since the structures of the resonance units 112_1, 112_2, ..., 112_N, ..., 112_M are substantially the same, the resonance unit 112_1 will be described here as follows.

The split ring resonator (ie, the resonance unit 112_1) includes an inner ring conductor C2 and an outer ring conductor C1. The inner annular conductor C2 has an inner radius r and an inner ring opening, and the outer annular conductor C1 has an outer ring opening and surrounds the inner annular conductor C2. The inner annular conductor C2 and the outer annular conductor C1 are electrically coupled to each other with a coupling distance d therebetween. In other words, the metamaterial of the present embodiment is a plurality of separate ring resonators that are periodically arranged.

The line widths of the inner annular conductor C2 and the outer annular conductor C1 may be the same or different, and the present invention is not limited thereto. In the embodiment of FIG. 2C, the line width of the inner ring-shaped conductor C2 is the same as the line width of the outer ring-shaped conductor C1 and is a predetermined width W. Furthermore, in the embodiment of FIG. 2C, the outer radius of the outer annular conductor C1 is equal to the sum of the inner radius r, the preset width w, and the coupling pitch d. The operating frequency band of the transmitting antenna 112 is determined according to the preset width W, the coupling pitch d, and the inner radius r. In an embodiment, the coupling pitch d may be the same as the preset width W described above, but the invention is not limited thereto.

That is to say, the signal characteristic of the microwave signal emitted by the transmitting antenna 112 is determined according to the structural size of the split ring resonator and the dielectric constant 介质 of the dielectric substrate 112P. The above signal characteristics include at least one of wavelength, amplitude and power of the microwave signal. In general, the operating frequency band of the transmitting antenna 112 can be adjusted by changing the structural size of each of the separate ring resonators. Therefore, after selecting the operating frequency band to be designed, the designer can design the structural size of each resonant unit correspondingly.

Since the metamaterial antenna has high signal gain characteristics, the microwave imaging system of the embodiment of the present invention can reduce the hardware volume of the entire system under the condition of ensuring high antenna gain by arranging the planar metamaterial antenna as the transmitting and receiving antenna of the microwave imaging system. .

The following will explain the different signal feeding methods. 3A and 3B are partial schematic views of a planar metamaterial antenna according to an embodiment of the invention. In the embodiment of FIG. 3A and FIG. 3B, the resonant unit can transmit the microwave signal through electrical coupling. Specifically, referring to FIG. 3A, the resonant unit 112_1 on the first surface S1 can transmit the microwave signal from the signal feeding port 112F1 via the at least one signal feeding line 112L1 on the second surface S2. Referring to FIG. 3B again, the resonant unit 112_1 on the first surface S1 can also transmit the microwave signal from the signal feed port 112F2 via the at least one signal feed line 112L2 on the first surface S1. The signal feed line 112L1 and the signal feed line 112L2 can be constructed on the substrate 112P by, for example, circuit printing. Alternatively, the dielectric substrate 112P is provided with a signal feed line connected to the signal feed port via the through hole, and the resonance unit 112_1 can transmit the microwave signal by electrically coupling with the signal feed line.

4A and 4B are partial schematic views of a planar metamaterial antenna according to an embodiment of the invention. In the embodiment of FIG. 4A and FIG. 4B, the resonant unit can transmit the microwave signal through electrical connection. Referring to FIG. 4A and FIG. 4B simultaneously, the resonant unit 112_1 can be coupled to the signal feeding port 112F3 via the through hole 112h of the dielectric substrate 112P. However, in the present embodiment, the outer ring-shaped conductor C1 of the resonance unit 112_1 is connected to the signal feed port 112F3 via the through hole 112h, but the present invention is not limited thereto. In other embodiments, the inner annular conductor C2 of the resonant unit 112_1 can also be connected to the signal feed port via the through hole. Alternatively, the signal substrate is connected to the signal feed line connected to the signal feed port via the through hole, and the resonance unit 112_1 can be directly connected to the signal feed line to transmit the microwave signal.

Here, although the above exemplary embodiment only describes the operation principle of the transmitting antenna 112 and the antenna structure, the operating principle of the receiving antenna 121 and the antenna structure are similar to those of the transmitting antenna 112, and thus will not be further described herein.

In summary, the embodiments of the present invention provide a microwave imaging system that is a microwave imaging system that uses a planar metamaterial antenna as a transceiver antenna. Compared with the use of the waveguide antenna as the transmitting and receiving antenna of the microwave imaging system, the embodiment of the present invention uses the planar metamaterial antenna as the transmitting and receiving antenna of the microwave imaging system, and thus the volume occupied by the antenna is relatively reduced. As a result, the portability of the microwave imaging system can greatly enhance the application range of the microwave imaging system, and is no longer limited to a specific medical site. In addition, by the structural size design of a plurality of separate ring resonators forming a metamaterial, the operating frequency bands of the signal transmitting circuit and the signal receiving circuit of the microwave imaging system can be adaptively adjusted, so that the microwave imaging system can be applied to various scanning modes. In the context of biological organization.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

10‧‧‧Microwave Imaging System

110‧‧‧ Signal transmitting circuit

111‧‧‧transmitter

112‧‧‧transmit antenna

120‧‧‧Signal receiving circuit

121‧‧‧ Receiver

122‧‧‧Receiving antenna

100‧‧‧ objects to be tested

130‧‧‧Signal Processing and Operation Circuit

140‧‧‧ computer

SS1, SS2‧‧‧ microwave signal

112_1, 112_2, 112_N, 112_M‧‧‧Resonance unit

112P‧‧‧ dielectric substrate

S1‧‧‧ first surface

S2‧‧‧ second surface

112G‧‧‧ ground plane

C1‧‧‧Outer ring conductor

C2‧‧‧ inner ring conductor

112L1, 112L2‧‧‧ signal feeder

112F1, 112F2, 112F3‧‧‧ signal feed 埠

112h‧‧‧through hole

FIG. 1 is a schematic diagram of a system architecture of a microwave imaging system according to an embodiment of the invention. 2A and 2B are schematic diagrams showing the structure of a planar metamaterial antenna according to an embodiment of the invention. FIG. 2C is a schematic structural diagram of a resonance unit according to an embodiment of the invention. 3A and 3B are partial schematic views of a planar metamaterial antenna according to an embodiment of the invention. 4A and 4B are partial schematic views of a planar metamaterial antenna according to an embodiment of the invention.

Claims (10)

A microwave imaging system includes: a signal transmitting circuit that emits at least one microwave signal having at least one frequency toward an object to be measured; a signal receiving circuit that receives the object reflected by the object to be tested and reflected by the object to be tested The microwave signal; and a signal processing and operation circuit coupled to the signal transmitting circuit and the signal receiving circuit for generating the microwave signals having different frequencies, and according to the signal receiving circuit Receiving the microwave signal to generate a detected image of the object to be tested, wherein a transmitting antenna of the signal transmitting circuit and a receiving antenna of the signal receiving circuit are each a planar metamaterial antenna, and the plane The metamaterial antenna includes a plurality of resonant units that are periodically arranged. The microwave imaging system of claim 1, wherein the resonant unit is disposed on a first surface of a dielectric substrate, and the resonant units are each a separate ring resonator. The microwave imaging system of claim 2, wherein the split ring resonator comprises: an inner annular conductor having an inner radius and an inner ring opening; and an outer annular conductor having an outer And a ring opening surrounding the inner annular conductor, wherein the inner annular conductor and the outer annular conductor are coupled to each other at a coupling distance. The microwave imaging system of claim 3, wherein the inner annular conductor has a line width that is the same as a line width of the outer annular conductor and is a predetermined width. The microwave imaging system of claim 4, wherein the operating frequency band of the receiving antenna and the transmitting antenna is determined according to the preset width, the coupling pitch, and the inner radius. The microwave imaging system of claim 4, wherein the coupling pitch is the same as the preset width. The microwave imaging system of claim 2, wherein the number of the resonant units is at least three. The microwave imaging system of claim 2, wherein the dielectric substrate is selected from the group consisting of a suspended substrate, a germanium substrate, a gallium arsenide substrate, a ceramic substrate, a glass substrate, a glass fiber substrate, a hydrocarbon ceramic substrate, and an iron. One of the fluorocarbon substrate, the Teflon glass fiber substrate, and the Teflon ceramic substrate. The microwave imaging system of claim 2, wherein a ground plane is disposed on the second surface of the dielectric substrate, and the resonant unit transmits at least one signal on the first surface or the second surface The feeder receives and transmits the microwave signal from a signal feed. The microwave imaging system of claim 2, wherein the resonant unit is coupled to a signal feed port via a through hole in the dielectric substrate.