Testing and measurement device and method for measuring properties of material under test

Abstract

To reduce the size of a device for measuring characteristics of a material concerning a radar.SOLUTION: A millimeter wave material testing device 100 measures transmission, reflectivity, an insertion loss, and the like, concerning a radar signal of a material 200. A reference unit 104 is in contact with a first surface of the material 200 under test, and a measuring device 102 is in contact with a back surface of the first surface of the material 200. A first transmitter of the measuring device 102 outputs a first radar signal at a predetermined frequency to an absorbing component of the reference unit 104 through the material 200. A first receiver receives a first reflection signal from the material 200. A second transmitter outputs a second radar signal at the predetermined frequency to a reflective component of the reference unit 104 through the material 200. A second receiver receives the reflective component and a second reflection signal from the material 200.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for measuring the radar characteristics of a material under test, and more particularly to a millimeter wave material testing apparatus and method for measuring the radar transmittance and reflectance of a material under test. [Background technology]

[0002] Many vehicles today have advanced driver assistance systems (ADAS), such as automatic emergency braking and lane change assist. These ADAS often use radar to detect whether other vehicles or objects are present and, for example, slow the vehicle down if necessary. Radar is used to emit radio waves and receive the reflections of the radio waves from the surface of the object to determine the range, angle, and relative speed of the object. Traditionally, many radar systems have used frequencies in the 24 GHz range, but many newer vehicles use frequencies in the 77 GHz range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-224414 A [Non-patent literature]

[0004] [Non-Patent Document 1] "Corner Cube" article, Wikipedia (Japanese version), [Online], [Retrieved June 8, 2020], Internet<https: / / ja.wikipedia.org / wiki / コーナーキューブ> [Non-Patent Document 2] "Draft angle of mold", Monozukuri Web, [online], [searched June 8, 2020], Internet<https: / / d-engineer.com / mold / nukikoubai.html> Summary of the Invention [Problem to be solved by the invention]

[0005] Various components of a vehicle can interact with or block radar radiation frequencies. This requires testing to ensure that the radar system can properly emit and receive radar signals in these desirable bands. Traditionally, coaxial cable systems are used to test these. However, coaxial cables capable of handling frequencies in the 77 GHz band are often very expensive and fragile.

[0006] Embodiments of the present invention address these and other deficiencies of the prior art. [Means for solving the problem]

[0007] The present invention provides a compact, robust millimeter wave test and measurement instrument capable of measuring radar-related characteristics of a material under test. The test and measurement instrument includes a measuring instrument and a reference unit between which a material under test is sandwiched when testing the material. The reference unit includes an absorbing component and a reflective component on a surface that contacts the material under test. The reference unit contacts the material under test on a first surface of the material. The measuring instrument contacts the material under test on a second surface behind the first surface of the material under test.

[0008] The measuring instrument has a transmitting / receiving surface having a first transmitter and a first receiver of a radar signal and a second transmitter and a second receiver on a contact surface that contacts the second surface of the material under test. The first transmitter outputs a first radar signal of a predetermined frequency through the material under test toward the absorbing component of the reference unit. The first receiver receives a first reflected signal from the material under test. At this time, the absorbing component absorbs the radar signal and does not reflect the first radar signal. Therefore, the first reflected signal is from the material under test. The second transmitter outputs a second radar signal of a predetermined frequency through the material under test toward the reflective component of the reference unit. The second receiver receives a second reflected signal from the reflective component and the material under test. The reflective component may be, for example, a corner cube, which reflects the signal toward the direction in which the signal was incident (see Non-Patent Document 1). The measuring instrument determines the transmittance, reflectance, insertion loss, etc. of the radar signal of the material under test based on the first and second reflected signals. These results may be displayed to a user through a display unit. At this time, it may be possible to simply display whether or not the standards for transmittance, reflectance, insertion loss, etc. are met.

[0009] An alignment mechanism may be provided on the contact surface of the measuring instrument with the material under test and the contact surface of the reference unit with the material under test to align the positional relationship between the absorbing component, the first transmitter, and the first receiver, and the positional relationship between the reflecting component, the second transmitter, and the second receiver to ensure appropriate positional relationships.

[0010] Also, before starting the measurement, the contact surface of the measuring instrument and the contact surface of the reference unit may be brought into contact without the material under test, and a calibration process (e.g., a process of setting the scales of the measuring instrument (transmittance, reflectance, insertion loss, etc.) to zero) may be performed. Also, without the material under test, a radar signal may be emitted toward the reflecting component, and the corresponding reflected signal may be recorded, and the characteristics of the material under test may be evaluated based on the difference in the reflected signal between the state with the material under test and the state without it.

[0011] Aspects, features and advantages of embodiments of the present invention will become apparent from the following description taken in conjunction with the drawings. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram of an example millimeter wave materials testing apparatus according to some embodiments of the present invention. [Diagram 2] FIG. 2 shows the example millimeter wave materials testing apparatus of FIG. 1 in use to test a material under test. [Diagram 3] FIG. 3 is a block diagram of the interface of the millimeter wave materials testing apparatus of FIG. [Figure 4] FIG. 4 is a block diagram of the contact surface of the reference unit of the millimeter wave materials testing apparatus of FIG. [Diagram 5] FIG. 5 is an example of a flowchart showing the operation of the millimeter wave material testing apparatus of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] This application discloses a millimeter waves material testing device that is handheld and can be used to assist in automobile manufacturing and repair. The millimeter waves material testing device can test materials such as, but not limited to, paints, coatings, bumpers, door panels, etc. for radar transmittance, reflectance, insertion loss, etc. The millimeter waves material testing device can be used to determine whether a radar signal passes through the material sufficiently, is reflected from the material, etc.

[0014] FIG. 1 illustrates an example of a millimeter wave materials testing instrument 100 according to some embodiments of the present invention. The millimeter wave materials testing instrument 100 may include a measuring instrument 102 and a reference unit 104. The measuring instrument 102 may include a display 106 that outputs information regarding the status of the test to a user. The millimeter wave materials testing instrument 100 is a lightweight, handheld device that can quickly test materials to ensure that they are adequately radar transparent for proper operation of radar systems, particularly automotive radar systems. In some embodiments, the millimeter wave materials testing instrument 100 may be battery powered.

[0015] The millimeter wave materials testing instrument 100 may also include one or more user inputs, which may include, for example, a button 108 for performing a test and a button 110 for performing a calibration, but the one or more user inputs are not limited to the buttons 108 and 110 shown in FIG. 1 and may include any input device, such as, but not limited to, a switch, a joystick, a touch screen, a keyboard, or the like.

[0016] In addition, a part of the contact surface of the measuring instrument 102 with the second surface of the material under test is a transmitter and receiver surface 112 for transmitting and receiving radar signals. 1. The corresponding surface 400 (not shown in FIG. 1 ) and test material Fee and As will be appreciated by those skilled in the art, instrument 102 may further include a number of hardware components, including, but not limited to, one or more processors, storage media, communication interfaces, and power sources.

[0017] 2 shows the millimeter wave material testing apparatus 100 being used to test a material 200. The material 200 is disposed between the measuring device 102 and the reference unit 104. As will be described in detail below, the transmitting and receiving surface 112 of the measuring device 102 and the corresponding surface 400 of the reference unit 104 include alignment mechanisms for aligning the measuring device 102 and the reference unit 104 with respect to each other through the material 200. The alignment mechanisms align the absorbing component 404 with a first transmitter and a first receiver, and the reflecting component 406 with a second transmitter and a second receiver, as described below, to a proper positional relationship. The alignment mechanisms may include, for example, corresponding magnets, corresponding pins and holes, or some other alignment mechanisms between the transmitting and receiving surface 112 and the contact surface 400 of the reference unit 104.

[0018] The user may select a run test button 108 or the like to instruct the instrument 102 to test the material 200 between the instrument 102 and the reference unit 102. Based on the results of the test, the display 106 may display relevant information to the user, as described in more detail below. For example, as shown in FIG. 2, the display 106 may output whether the material 200 under test passed the transmission and reflection tests. In this example, the display 106 simply outputs whether the material 200 passed or failed, but embodiments of the present invention are not limited to outputting such a summary and may provide more information, such as a graphical representation of the material's transmission, reflectivity, insertion loss, etc.

[0019] FIG. 3 illustrates an example of a transmit / receive face 112 of a measuring instrument 102 according to some embodiments of the present invention. The transmit / receive face 112 includes first and second transducer pairs 305 and 307. Each of these two transducer pairs consists of a transmitter pair (two transmitters) 302 and a receiver pair (two receivers) 304. Each transducer pair can be activated separately. The receive and transmit sides are disposed on the transmit / receive face 112, which may be a printed circuit board. PlaceTherefore, like a typical antenna, the surface wave coupling (propagation on the transmitting / receiving surface 112) is net zero, and the antenna is primarily sensitive to signals orthogonal to the transmitting / receiving surface 112.

[0020] Circuitry 306 is located at the edge of transmit / receive face 112. Circuitry 306 may be under a protective panel on transmit / receive face 112. Circuitry 306 may include, for example, a frequency modulated (FM) continuous wave (CW) chirp radar integrated circuit, which may support multiple input / output channels. Transmitter 302 and receiver 30 4 The antenna may be printed directly on the surface of the transmitting / receiving surface 112.

[0021] Additionally, the transmit / receive surface 112 includes an alignment feature that ensures that the transmit / receive surface 112 is aligned with a corresponding surface 400 of the reference unit 104. 3 In the embodiment shown in teeth, Transmitting / receiving surface 112 To There are a number of different magnets 308 (either north or south polarity) that magnetically attract corresponding magnets of opposite polarity in the reference unit 104. This magnetic force automatically ensures proper alignment of the transmit / receive face 112 with the corresponding face 400 of the reference unit 104.

[0022] 4 shows an example of a surface 400 of the reference unit 104. The surface 400 is also a contact surface that contacts the first surface of the material under test 200. The surface 400 of the reference unit 104 has a corresponding alignment mechanism that aligns the transmitting and receiving surface 112 of the measuring instrument 102 with the surface 400 of the reference unit 104. In FIG. 4, the alignment mechanism has a corresponding magnet 402 of opposite polarity to the magnet on the transmitting and receiving surface 112. This allows the positional relationship between the absorbing component 404 and the first transmitter and first receiver (antennas) of the transmitting and receiving surface 112, and the positional relationship between the reflecting component 406 and the second transmitter and second receiver (antennas) of the transmitting and receiving surface 112 to be properly aligned, as described below.

[0023] Surface 400 also has an absorptive (or non-reflective) component 404 and a reflective component 406. Absorptive component 404 absorbs the transmitted radar, allowing instrument 102 to determine the signal that is reflecting directly off of material 200. Reflective component 406 reflects the signal back to instrument 102, allowing instrument 102 to determine how well the material under test allows the signal to pass through.

[0024] The absorbing component 404 may be any component or surface that absorbs the transmitted signal, and the reflecting component 406 may be any component or surface that reflects the signal. In some embodiments, the reflecting component 406 is a corner cube, which is a retroreflector consisting of three mutually perpendicularly interlocking flat surfaces that reflect the signal back towards the signal source from which it came. Corner cubes are effective in situations where a non-contact, highly reflective section is required, regardless of angle or alignment. Corner cubes allow the incoming signal to be reflected off multiple faces of highly reflective materials such as aluminum, silver, copper, etc., directly back to the signal source, even if misaligned (see Non-Patent Document 1). Metal surfaces with an oxide coating, such as aluminum, work well for reflection, as the oxide form is low-loss and highly transparent to the reflective aluminum underneath the oxide coating.

[0025] The corner cubes may be molded (cast) from metal and then plated, or in some embodiments, the corner cubes may be made from plastic and then plated. The exposed areas of the corner cubes may be covered with a dielectric film over the entire surface, may be passivated, or may be left to oxidize naturally. Being molded parts, the corner cubes are available at a relatively low cost, and the outer edge or back of the reference unit 104 may have a large draft angle or a cavity to reduce the cost of molding the reflective component 406.

[0026] In some embodiments, both surfaces 112 and 400 are smooth and abrasion resistant, allowing the meter 102 and reference unit 104 to slide along the material under test without scratching the material under test. This allows, for example, testing of different parts of a single material under test (such as a car bumper), and even for parts that are small and fixed to the car body, in some cases, testing can be performed by moving the meter 102 and reference unit 104 rather than moving the material under test.

[0027] 5 is a flow chart illustrating an example operation of the millimeter wave material test apparatus 100 according to some embodiments of the present invention. First, in optional step 500, the user may calibrate the measuring instrument 102. To do this, the user may place the reference unit 104 directly on the measuring instrument 102 and align the measuring instrument's transmit / receive face 112 with the reference unit's face 400 using the alignment features of both the measuring instrument 102 and the reference unit 104. The user then selects button 110 to calibrate the measuring instrument 102 (e.g., zeroing out the transmittance, reflectance, insertion loss, etc.).

[0028] In step 502, a material to be tested, such as material 200 described above, is placed between the gauge 102 and the reference unit 104. Material 200 may be, for example, a fender panel or door panel of an automobile. Because the material may be large, alignment features on surfaces 112 and 400 ensure that the gauge 102 and reference unit 104 are aligned so that an accurate measurement of the material can be made.

[0029] In step 504, input for a test run on the material to be tested is received from the instrument 102. Upon receiving the input for a test run on the material, in step 506, the transmitter 302 of the first transducer pair 305 may output a signal at a predetermined frequency and the corresponding receiver 304 may measure the returning signal (return signal). In step 508, the transmitter 302 of the second transducer pair 307 may output a signal at a predetermined frequency and the corresponding receiver 304 may measure the return signal. As described above, one transmitted signal is output toward the absorbing component 404, so that the return signal measured by the corresponding receiver 304 is the total signal reflected from the material 200. The other signal transmitted at the predetermined frequency is output toward the reflecting component 406, so that the return signal measured by the corresponding receiver 304 is the total signal reflected from the material 200 plus the reflected signal from the reflecting component 406. In some embodiments, the predetermined frequency can be varied. In some embodiments, the instrument 102 can transmit and measure test signals at multiple discrete predetermined frequencies, hi some embodiments, the instrument 102 can sweep the frequency (continuously change the frequency) across a predetermined frequency range.

[0030] In step 510, the two return signals may be used by a processor in the instrument 102 to determine whether the material 200 properly passes signals at a predetermined frequency. In some embodiments, the processor in the instrument 102 may determine the insertion loss of the material and determine whether the insertion loss is within an acceptable range. The insertion loss may be determined using any known method based on the transmitted and received signals. The processor may output a pass / fail result as shown in FIG. 2, or may output a more detailed result, such as the processor displaying a graph of the response of the received signal to the frequency of the transmitted signal. The predetermined frequency may be selected by the user or may be stored in the memory in the instrument 102. According to the operation shown in FIG. 5, the millimeter wave material testing apparatus 100 according to the present invention can test materials such as paints, coatings, bumpers, door panels, etc. for radar transmittance, reflectance, etc., and quickly output whether the material passes (does not cause interference with) the radar required to operate the radar system.

[0031] The reference unit 104 and meter 102 can be separated from the material 200 and slid sideways relative to the material 200 to test a different portion of the material. An alignment mechanism, such as a magnet or pin and hole mechanism, can also ensure that the reference unit 104 and meter 102 are aligned for the next reading of the material 200. Due to the small size of the body, in some situations, testing can be performed even in situations where it is difficult to move the material under test, for example, when the material is already fixed to the body of an automobile.

[0032] Aspects of the invention can operate on specially created hardware, firmware, digital signal processors, or specially programmed general-purpose computers, including processors that operate according to programmed instructions. The term "controller" or "processor" in this application contemplates microprocessors, microcomputers, ASICs, and dedicated hardware controllers, among others. Aspects of the invention can be implemented in computer-available data and computer-executable instructions, such as one or more program modules, executed by one or more computers (including a monitoring module) or other devices. Generally, program modules include routines, programs, objects, components, data structures, and the like, which, when executed by a processor in a computer or other device, perform particular tasks or implement particular abstract data formats. The computer-executable instructions may be stored in computer-readable storage media, such as hard disks, optical disks, removable storage media, solid-state memory, RAM, and the like. As will be appreciated by those skilled in the art, the functionality of the program modules may be combined or distributed as desired in various embodiments. Furthermore, such functionality may be embodied in whole or in part in firmware or hardware equivalents, such as integrated circuits, field programmable gate arrays (FPGAs), etc. One or more aspects of the present invention may be more effectively implemented using certain data structures, and such data structures are considered to be within the scope of the computer-executable instructions and computer-usable data described herein.

[0033] The disclosed aspects may, in some cases, be implemented in hardware, firmware, software, or any combination thereof. The disclosed aspects may also be implemented as instructions carried by or stored on one or more computer-readable media that may be read and executed by one or more processors. Such instructions may be referred to as computer program products. A computer-readable medium as described herein means any medium that can be accessed by a computing device. By way of example, and not limitation, computer-readable media may include computer storage media and communication media.

[0034] Computer storage media means any medium that can be used to store computer readable information. By way of example, and not limitation, computer storage media may include Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), Flash memory or other memory technologies, Compact Disc Read Only Memory (CD-ROM), Digital Video Disc (DVD) and other optical disk storage devices, magnetic cassettes, magnetic tape, magnetic disk storage devices and other magnetic storage devices, and any other volatile or non-volatile removable or non-removable media implemented in any technology.

[0035] A communication medium refers to any medium capable of communicating computer readable information. By way of example, and not limitation, communication media may include coaxial cables, fiber optic cables, air, or any other medium suitable for communicating electrical, optical, radio frequency (RF), infrared, acoustic, or other types of signals.

[0036] Working Example In the following, examples useful for understanding the technology disclosed in the present application are presented. The embodiment of the technology may include one or more of the examples described below and any combination thereof.

[0037] Example 1 is a test and measurement device, a reference unit having a reflective component and an absorptive component and having a contact surface configured to contact a first side of a material under test; a meter having a contact surface configured to contact a second side of the material under test opposite the first side; Equipped with The above measuring instrument, a first transmitter configured to output a first signal at a predetermined frequency through the material under test toward the absorbing component of the reference unit; a first receiver configured to receive a first reflected signal from the material under test; a second transmitter configured to output a second signal at the predetermined frequency through the material under test toward the reflective component of the reference unit; a second receiver configured to receive a second reflected signal from the reflecting component; It has.

[0038] Example 2 is the test and measurement device of Example 1, wherein the meter further comprises a processor configured to determine whether the material under test meets predetermined requirements based on the first signal, the second signal, the first reflected signal, and the second reflected signal.

[0039] Example 3 is the test and measurement device of Example 2, wherein the processor is further configured to determine whether the material under test passes a reflection criterion based on the first reflected signal, and to determine whether the material under test passes a transmission criterion based on the second reflected signal.

[0040] Example 4 is the test and measurement device of Example 2 or 3, wherein the measuring device further comprises a display configured to output a determination result as to whether the material under test satisfies a predetermined requirement.

[0041] Example 5 is the test and measurement apparatus of any of Examples 1 to 4, further comprising an alignment mechanism configured to align the contact surface of the reference unit with the contact surface of the measuring instrument to bring the first transmitter and the first receiver into a corresponding positional relationship with the absorbing component, and to bring the second transmitter and the second receiver into a corresponding positional relationship with the reflective component.

[0042] Example 6 is the test and measurement instrument of example 5, in which the alignment mechanism includes a magnet on the contact surface of the reference unit and a corresponding magnet on the contact surface of the meter.

[0043] Example 7 is the test and measurement instrument of any of Examples 1 to 6, wherein the reference unit is further configured to make direct contact with the meter during a calibration operation.

[0044] Example 8 is the test and measurement instrument of example 7, wherein the measuring instrument comprises an input means for initiating the calibration operation.

[0045] Example 9 is the test and measurement apparatus of any of Examples 1 to 8, wherein the first transmitter and the first receiver are a first transducer pair having two first transmitters and two first receivers.

[0046] Example 10 is the test and measurement apparatus of example 9, in which the second transmitter and the second receiver are a second transducer pair having two second transmitters and two second receivers.

[0047] An eleventh embodiment is the test and measurement instrument of any one of the first to tenth embodiments, wherein the predetermined frequency is a frequency related to an output signal of a radar system.

[0048] Example 12 is the test and measurement instrument of any of Examples 1 to 11, wherein the test and measurement instrument is handheld.

[0049] Example 13 is a method for measuring a property of a material to be tested, comprising: transmitting a first signal at a predetermined frequency through a material under test towards an absorbing component; receiving a first response signal in response to transmitting the first signal; transmitting a second signal of the predetermined frequency through the material under test toward a reflective component; receiving a second response signal in response to transmitting the second signal; A process for determining the insertion loss of the material under test. It is equipped with:

[0050] Example 14 is the method of example 13, further comprising determining whether the insertion loss of the material meets a predetermined requirement.

[0051] Example 15 is the method of example 14, further comprising displaying a determination of whether the material under test meets the predetermined requirements.

[0052] Example 16 is the method of any of examples 13 to 15, further comprising aligning a contact surface of the measuring device and a contact surface of the reference unit with an alignment mechanism.

[0053] Example 17 is the method of example 16, wherein the alignment mechanism comprises a magnet on the contact surface of the reference unit and a complementary magnet on the contact surface of the measurement instrument.

[0054] Example 18 is the method of any of Examples 13 to 17, transmitting the first signal at the predetermined frequency towards the absorbing component without the material under test; receiving a third response signal in response to transmitting the first signal; transmitting the second signal at the predetermined frequency toward the reflective component without the material under test; receiving a fourth response signal in response to transmitting the second signal; The present invention further comprises a calibration process having the following steps:

[0055] Example 19 is any of the methods of Examples 13 to 18, wherein the first transmitter that transmits the first signal and the first receiver that receives the first response signal are a first transducer pair having two first transmitters and two first receivers.

[0056] Example 20 is the method of any of examples 13 to 19, wherein the predetermined frequency is a frequency associated with an output signal of a radar system.

[0057] Example 21 is any of the methods of Examples 13 to 20, wherein the second transmitter that transmits the second signal and the second receiver that receives the second response signal are a second transducer pair having two second transmitters and two second receivers.

[0058] The above-described versions of the disclosed subject matter have many advantages that have been described or that will be apparent to those of skill in the art. Nevertheless, not all of these advantages or features are required in every version of a disclosed device, system or method.

[0059] In addition, the description of this application refers to specific features. It should be understood that the disclosure herein includes all possible combinations of those specific features. When a particular feature is disclosed in the context of a particular aspect or embodiment, that feature can also be used in the context of other aspects and embodiments, to the extent possible.

[0060] Furthermore, when the application refers to a method having two or more defined steps or processes, those defined steps or processes may be performed in any order or simultaneously, unless the context precludes such a possibility.

[0061] For convenience of illustration, specific embodiments of the invention have been illustrated and described, but it will be understood that various changes can be made therein without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. [Explanation of symbols]

[0062] 100 Millimeter wave material testing equipment 102 Measuring Instruments 104 Reference Unit 106 Display section 108 Test execution button 110 Calibration execution button 112 Transmitting / receiving surface (part of contact surface) 200 Test material 302 Transmitter Pair 304 Receiver Pair 305 1st transducer pair 306 Circuit 307 2nd Transducer Pair 308 Alignment mechanism magnet 400 Reference Unit Contact Surface 402 Alignment mechanism magnet 404 Absorption Components 406 Reflective Components

Claims

1. a reference unit having a reflective component and an absorptive component and configured to contact a first side of the material under test; a meter configured to contact a second side of the material under test opposite the first side; Equipped with The above measuring instrument, a first transmitter configured to output a first millimeter wave signal at a predetermined frequency through the material under test towards the absorbing component of the reference unit; a first receiver configured to receive a first reflected signal from the material under test; a second transmitter configured to output a second millimeter wave signal at the predetermined frequency through the material under test toward the reflective component of the reference unit; a second receiver configured to receive a second reflected signal from the reflecting component; A test and measurement device having:

2. 2. The test and measurement instrument of claim 1, wherein the measuring instrument further comprises a processor configured to determine whether the material under test meets predetermined requirements based on the first millimeter wave signal, the second millimeter wave signal, the first reflected signal, and the second reflected signal.

3. 3. The test and measurement instrument of claim 2, wherein the processor is further configured to determine whether the material under test passes a reflectance standard based on the first reflected signal.

4. 4. The test and measurement instrument of claim 2 or 3, wherein the processor is further configured to determine whether the material under test passes a transmission criterion based on the second reflected signal.

5. A method of measuring a property of a material under test using a test and measurement device having a reference unit having a reflective component and an absorptive component and configured to contact a first side of the material under test, and a measuring instrument configured to contact a second side of the material under test opposite the first side, comprising: transmitting a first millimeter wave signal at a predetermined frequency through the material under test towards the absorbing component of the reference unit with a first transmitter of the instrument; receiving a first response signal by a first receiver of the measuring device in response to transmission of the first millimeter wave signal; transmitting a second millimeter wave signal at the predetermined frequency through the material under test towards the reflective component of the reference unit with a second transmitter of the instrument; receiving a second response signal by a second receiver of the measuring device in response to transmission of the second millimeter wave signal; The measuring instrument determines a transmittance, a reflectance, or an insertion loss of the material under test based on the first response signal and the second response signal. A method for measuring properties of a material under test comprising:

6. A process in which the first transmitter transmits the first millimeter wave signal of a predetermined frequency toward the absorbing component without the material under test; receiving, by the first receiver, a third response signal in response to transmission of the first millimeter wave signal; transmitting, by the second transmitter, the second millimeter wave signal at the predetermined frequency towards the reflective component without the material under test; receiving a fourth response signal by the second receiver in response to transmitting the second millimeter wave signal; 6. The method of claim 5, further comprising a calibration process comprising:

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