JP4485985B2 - Dielectric property measuring method and conductivity measuring method - Google Patents

Description

  The present invention relates to a dielectric property measuring method for measuring a dielectric constant or dielectric loss tangent of a dielectric material used as an electronic component or a circuit board, particularly in the millimeter wave region, and a conductivity measurement for measuring the conductivity of a conductor material. Regarding the method.

  To calculate impedance and transmission loss of microstrip lines, strip lines, coplanar lines, etc. used for circuit boards and semiconductor device packages, it is not possible to measure the dielectric constant and dielectric loss tangent of dielectric substrates used for these. is important. In recent years, in-vehicle radars and millimeter-wave wireless LANs have been developed, and measurement values of the relative permittivity and dielectric loss tangent of the substrate in the millimeter-wave region have become necessary for designing these circuits.

In general, a flat dielectric sample is used to obtain the relative dielectric constant and dielectric loss tangent of the substrate material. As a dielectric property measurement method, a measurement method using a cavity resonator having a shape as shown in FIG. 5 is defined as a JIS standard (see Non-Patent Document 1). In this measurement method, two holes are formed in the cavity resonator, and a minute loop antenna 72 provided at the tip of the coaxial cable 71 is inserted through each hole, thereby exciting and detecting the cavity resonator. Then, the resonance frequency and no-load Q of this cavity resonator are measured, and the dielectric characteristics of the flat plate dielectric sample 8 are obtained.
Dielectric property measurement method in millimeter wave band of JIS fine ceramics (JIS R 1660-1: 2004)

  However, a micro loop antenna used in millimeter waves has a small loop diameter and requires special processing for its production, and is therefore very expensive. Further, the structure is a structure in which the core wire at the tip is narrowed and joined to the outer conductor by welding, and is very fragile against an impact and requires delicate handling. Furthermore, although the excitation method using a small loop antenna has a characteristic that a mode can be selected depending on the angle of the loop surface, an unnecessary mode cannot be completely suppressed, resulting in an obstacle to the mode used for measurement. .

  It is an object of the present invention to provide a dielectric property measuring method and a conductivity measuring method that can be easily handled in the millimeter wave band and can suppress unnecessary modes as compared with the prior art.

  According to the present invention, an input side and an output side NRD guide are configured by sandwiching a pair of dielectric strips between the upper and lower flat conductors so that the tips are close to each other. Input-side and output-side slots are respectively formed on the tips of the dielectric strips of the input-side and output-side NRD guides, and the dielectrics are respectively provided from the input-side and output-side slots between the tips of the pair of dielectric strips. A blocking wall made of a conductor is provided at a position equidistant in the extending direction of the body strip so as to extend over the upper and lower flat conductors, and covers the input side and output slots in parallel to the upper flat conductor. A conductor plate is disposed, and a dielectric sample is disposed between the conductor plate and the upper flat conductor so that the input side and the output side slots are between Configuring a resonator, exciting the TE mode of the resonator, measuring the resonance frequency and no-load Q of the resonator, and obtaining the dielectric characteristics of the dielectric sample from the resonance frequency and the no-load Q This is a characteristic dielectric property measuring method.

  Here, it is preferable to form a cavity resonator between the upper flat conductor and the conductor plate.

  In the present invention, a pair of dielectric strips are sandwiched between the upper and lower flat conductors so that the tips are close to each other to form an input side and output side NRD guide. The input side and output side slots are formed on the leading ends of the dielectric strips of the input side and output side NRD guides, respectively, and between the leading ends of the pair of dielectric strips, from the input side and output side slots, respectively. A barrier wall made of a conductor is provided at an equidistant position in the extension direction of the dielectric strip so as to extend over the upper and lower flat conductors, and covers the input and output slots in parallel to the upper flat conductor. A conductive plate is disposed on the input side and a slot is formed between the input side and output side slots, and the TE mode of the resonator is excited to resonate the resonator. Measuring the wavenumber and unloaded Q, a conductivity measuring method characterized by determining the conductivity of the conductor plate from the resonant frequency and the unloaded Q.

  Here, it is preferable to form a cavity resonator between the upper flat conductor and the conductor plate.

  According to the dielectric property measurement method and the conductivity measurement method of the present invention, it can be easily handled in the millimeter wave band, and the unnecessary mode is suppressed as compared with the conventional method, and the relative permittivity, dielectric loss tangent, conductivity of the resonator. Etc. can be measured.

Embodiments of the present invention will be described with reference to the drawings.
In the present invention, as shown in FIG. 1, a pair of dielectric strips 31 and 41 are sandwiched between an upper plate-like conductor 1 and a lower plate-like conductor 2 so that their tips are close to each other. And the output side NRD guide 4, and the input side slot 11 and the output side slot 12 on the tips of the dielectric strips 31 and 41 of the input side NRD guide 3 and the output side NRD guide 4 with respect to the upper plate-like conductor 1, respectively. And the upper plate-like conductor 1 between the tips of the pair of dielectric strips 31 and 41 at equal distances from the input side slot 11 and the output side slot 12 in the extending direction of the dielectric strips 31 and 41, respectively. In addition, a blocking wall 4 made of a conductor is provided so as to extend over the lower flat conductor 2, and an input slot 11 and an output slot are parallel to the upper flat conductor 1. 2, the conductor plate 61 is disposed, and the dielectric sample 62 is disposed between the conductor plate 61 and the upper plate-like conductor 1, and the resonator 6 is configured between the input side slot 11 and the output side slot. The dielectric property measuring method is characterized in that the dielectric mode of the dielectric sample 62 is obtained by exciting the TE mode of the resonator 6 and measuring the resonance frequency and no-load Q of the resonator 6.

  The input-side NRD guide 3 includes a part of the upper flat conductor 1, a part of the lower flat conductor 2, and a dielectric strip 31. The output-side NRD guide 4 includes a part of the upper flat conductor 1, a part of the lower flat conductor 2, and a dielectric strip 41. Here, the NRD guide means a non-radiative dielectric line.

The upper flat conductor 1 and the lower flat conductor 2 are made of a material having high conductivity such as copper or silver, and have a thickness that does not easily bend. Moreover, those for the area of the upper flat conductor 1 and the lower flat conductor 2 when viewed from above, for example, the vertical length _{L 1} is 30～90Mm, horizontal length _{L 2} of 50~110mm Is adopted. The distance between the upper flat conductor 1 and the lower flat conductor 2 is 1 / 2λg or less, and is usually fixed to 1 to 3 mm, where λg is a wavelength in a dielectric strip to be described later.

  The dielectric strip (dielectric line) 31 and the dielectric strip (dielectric line) 41 have their tips close to each other so as to be sandwiched between the upper flat conductor 1 and the lower flat conductor 2. Are arranged. These are made of a low-loss dielectric material such as Lexolite (registered trademark). The height of the dielectric strip 31 and the dielectric strip 41 is usually 1 to 3 mm, which is the same as the distance between the upper flat conductor 1 and the lower flat conductor 2, and the width is also usually 1 to 3 mm. The length L3 of the part clamped between the upper flat conductor 1 and the lower flat conductor 2 of the strips 31 and 41 is 20 to 55 mm.

  An input side slot 11 is formed on the dielectric strip 31 of the input side NRD guide 3 in the upper flat conductor 1, and on the dielectric strip 41 of the output side NRD guide 4 in the upper flat conductor 1, An output side slot 12 is formed. Here, the input side slot 11 and the output side slot 12 are preferably a rectangle or a hole whose corner is formed in R, and the size thereof is such that only the magnetic field component does not pass but the electric field component does not pass. It is preferable that the size, in other words, the size of the dielectric strips 31 and 41 is such that the length of the side along the longitudinal direction of the dielectric strip is such that the electric field does not enter in order to couple the resonator with the magnetic field. Λg is preferably 1 / 8λg to 1 / 2λg, and the length of the sides along the width direction of the dielectric strips 31 and 41 is 0.05 w when the width of the dielectric strips 31 and 41 is w. ~ W is preferred.

  Then, from the conductor so as to cover the upper plate-like conductor 1 and the lower plate-like conductor 2 so as to cut off the tips of the dielectric strip 31 of the input-side NRD guide 3 and the dielectric strip 41 of the output-side NRD guide 4. A blocking wall 5 is provided. The blocking wall 5 is made of a material having a high conductivity such as copper or silver, like the upper flat conductor 1 and the lower flat conductor 2. The position where the blocking wall 5 is provided is a position that is equidistant from the input side slot 11 and the output side slot 12 in the extending direction of the dielectric strips 31 and 41, in other words, from the input side slot 11 to the dielectric strip. The distance from the output side slot 12 to the barrier wall 5 along the longitudinal direction of the dielectric strip 41 is substantially equal to the distance until the barrier wall 5 is reached along the longitudinal direction of 31. At this time, the distance between the center position of the input side slot 11 and the output side slot 12 and the blocking wall 5 is the maximum magnetic field position when the distance is λg / 4, which is convenient for magnetic field coupling. The fine adjustment of the coupling is performed by increasing or decreasing the distance between the dielectric strips 31 and 41 and the blocking wall 5.

  Here, as the pair of slots are named as the input side slot 11 and the output side slot 12, a part of the upper flat conductor 1 (including the input side slot 11 and the output side slot 12 and facing a conductor plate 61 described later) Area) constitutes the resonator 6, in other words, the resonator 6 is constituted between the input side slot 11 and the output side slot, and the input side slot 11 is connected to the resonator 6 by magnetic field coupling. The resonator 6 is excited and is output from the output side slot 12 for detection. Further, a further part (dielectric strip 31, part of the upper plate-like conductor 1 constituting the resonator 6 (a region including the input side slot 11 and the output side slot 12 and facing a conductor plate 61 described later). 41) is also a part of the input-side NRD guide 3 and a part of the output-side NRD guide 4. The resonator 6 and the input-side NRD guide 3, and the resonator 6 and the output-side NRD guide 4 It is supposed to be shared.

  The resonator 6 includes a conductor plate 61 arranged so as to cover the input side slot 11 and the output side slot 12 in parallel with the upper flat conductor 1. The conductor plate 61 is made of a material having high conductivity such as copper or silver, and has a thickness that does not easily bend, like the upper plate-like conductor 1 and the lower plate-like conductor 2. Further, the area viewed from above the conductor plate 61 is not limited as long as it covers the input side slot 11 and the output side slot 12, but the size shown in the drawing is preferable.

  As shown in FIG. 1, a flat dielectric sample 62 is disposed as a dielectric sample between the conductor plate 61 and the upper flat conductor 1. Specifically, a conductor wall 63 is provided on the upper flat conductor 1, a flat dielectric sample 62 is placed on the conductor wall 63, and a conductive plate is further placed on the flat dielectric sample 62. 61 is mounted to form a box-shaped cavity resonator. Although the height of the cavity resonator varies depending on the measurement frequency, for example, it is preferable that the measurement frequency is 3 to 5 mm when the measurement frequency is 60 GHz. It is sufficient that the output side slot 12 is accommodated and is not too large as shown in the figure. This cavity resonator is a box type having an internal space sealed by a conductor wall 63, and has a configuration in which a flat dielectric sample 62 and a conductor plate 61 are simply placed on the conductor wall 63. However, the present invention is not limited to such a shape, and may have a slight gap as long as the structure does not radiate an electromagnetic field. In FIG. 1, the flat dielectric sample 62 is arranged on the conductor wall 63, but the flat dielectric sample 62 may be arranged below the conductor wall 63. Further, in FIG. 1, a box-shaped cavity resonator is configured by erecting a conductor wall 63 on the upper flat conductor 1, but a box having the same slot as the upper flat conductor on the bottom surface. A mold cavity resonator may be mounted on the upper flat conductor 1. Furthermore, instead of using a flat dielectric sample, a cylindrical dielectric sample may be disposed in the cavity resonator.

  The TE mode of the resonator 6 is excited to measure the resonance frequency and no-load Q of the resonator 6, and the dielectric characteristics such as relative permittivity and dielectric loss tangent are obtained from the resonance frequency and no-load Q.

  This measurement method is characterized in that an input side slot 11 and an output side slot 12 are provided in the upper flat conductor 1 constituting the input side NRD guide 3 and the output side NRD guide 4 to excite the resonator 6. . The greatest advantage of using an NRD guide is that it can be easily converted from a waveguide (not shown but connected to the NRD guide) and is easy to implement. Further, since there is almost no direct coupling between the lines due to the blocking wall 5, the dynamic range can be lowered to the noise level. Furthermore, it is possible to suppress other unnecessary modes than the measurement method using the conventional minute loop antenna, and there is an advantage that only the resonance peak to be measured can be excited.

Further, the arrangement of the dielectric strips 31 and 41 is not necessarily a linear arrangement as shown in FIG. 1, and is deviated from the straight line by a predetermined angle to suppress unnecessary modes, for example, as shown in FIG. This angle is not particularly limited as long as it is a measurable angle. For example, when the mode to be suppressed is TM ₃₁₀ , a position where the angle is shifted from a linear arrangement to 30 degrees or minus 30 degrees is adopted.

  Further, the present invention is not limited to the measurement of the flat dielectric sample 62 as shown in FIG. 1, and as shown in FIG. 3, a cylindrical dielectric as a dielectric sample between the conductor plate 61 and the upper flat conductor 1. It is also possible to arrange the body sample 64 and measure the dielectric characteristics of the cylindrical dielectric sample 64.

  In the resonator having the structure shown in FIG. 3, the resonator is configured such that the cylindrical dielectric sample 64 is sandwiched between the conductor plate 61 and the upper flat conductor 1. Here, it is preferable that the cylindrical dielectric sample 64 is disposed at the approximate center between the input side slot 11 and the output side slot 12. The diameter and height of the cylindrical dielectric sample 64 can be designed by a predetermined arithmetic expression (see Non-Patent Document 1) when the measurement frequency is specified and the approximate value of the relative dielectric constant and the measurement mode are specified.

  In FIG. 3, the upper surface of the cylindrical dielectric sample 64 and the lower surface of the conductor plate 61 are in contact with each other, but there may be a slight gap therebetween.

  In the dielectric property measurement method using the resonator having the structure shown in FIG. 3, the magnetic field using the input side slot 11 and the output side slot 12 is the same as the measurement method using the resonator having the structure shown in FIG. Due to the coupling, excitation and detection of the resonator composed of the upper flat conductor 1, the conductor plate 61, and the cylindrical dielectric sample 64 are performed, and the resonance frequency and no-load Q of the resonator are measured with a network analyzer, The dielectric properties (dielectric constant, dielectric loss tangent) of the cylindrical dielectric sample 64 can be obtained.

  Furthermore, the structure using the resonator according to the present invention is a method for measuring the conductivity of the conductor plate 61 constituting the resonator in addition to measuring the dielectric characteristics of the dielectric sample as shown in FIGS. Also found that can be adopted.

  The structure shown in FIG. 4 is substantially the same as the structure shown in FIG. 1 except that the flat dielectric sample 62 in FIG. 1 is removed. That is, in FIG. 4, a resonator is constituted by the conductor plate 61, the conductor wall 63, and the upper flat conductor 1.

  In the method for measuring conductivity using the resonator having the structure shown in FIG. 4, the input side slot 11 and the output side slot 12 are provided in the same manner as the dielectric property measuring method using the resonator having the structure shown in FIG. Due to the magnetic field coupling used, excitation and detection of the resonator composed of the upper flat conductor 1, the conductor plate 61, and the conductor wall 63 are performed, and the resonance frequency and no-load Q of this resonator are measured with a network analyzer, The conductivity of the conductor plate 61 can be obtained.

  At the time of measurement, after configuring the cavity resonator, the resonance frequency f1 and unloaded Q and Qu1 are measured, and the conductivity σ of all the conductors constituting the resonator is evaluated, and then a conductor plate which is a component of the resonator By replacing 61 with the conductor plate 61 whose conductivity is to be obtained and measuring in the same manner, the conductivity σ2 of the conductor plate 61 to be obtained is calculated from the measurement results of the unloaded Q and Qu2 and the conductivity σ.

  In the measurement method using the resonator having the structure shown in FIG. 4, the measurement method of conductivity is used. However, the measurement method is not limited to obtaining the conductivity, and obtaining the calculated resistivity or surface resistance. Shall also be included.

Using the structure shown in FIG. 3, the frequency characteristic of the cavity resonator was measured by the measurement method of the present invention (NRD guide slot excitation (NRD)). The measurement results are shown in FIG. On the other hand, FIG. 7 shows the measurement results of the frequency characteristics of the cavity resonator by the conventional measurement method (micro loop antenna excitation (Loop)) shown in FIG. Here, the conductor wall 63 portion has the same value because it can be used in common in the two measurements. The dimensions (diameter D, height H) of the resonator are as shown in Table 1 based on the resonance frequency. Incidentally, the upper and lower flat conductor 1, 2 and the blocking wall 5 is made of copper, the length of the vertical _{L 1} is 60 mm, the length of the horizontal _{L 2} is 80 mm, the thickness was 2 mm. The dielectric strips 31 and 41 are made of Lexolite (registered trademark), the width is 2 mm, the height is 2.2 mm, and the length of the dielectric strips 31 and 41 at the position sandwiched between the upper and lower flat conductors is 30 mm. Met.

As apparent from FIGS. 6 and 7, the measurement method using NRD guide slot excitation (NRD) of the present invention can suppress other unnecessary modes after exciting the TE ₀₁₁ mode used for measurement. Recognize.

The measurement results of the two resonance frequencies f0 are shown in the left column 1 of Table 1.

  Next, a cavity resonator having the structure shown in FIG. 1 was prepared, and a sapphire sample with a thickness t = 0.335 mm and an LTCC sample with a t = 0.504 mm were measured. The measurement results of the frequency response of these samples are shown in FIGS.

From this result, it was confirmed that the TE ₀₁₁ mode used for the measurement of the present invention was clearly excited. It was also found that unnecessary mode was well suppressed.

  The measurement results of the resonance frequency f0 at this time are shown in columns 2 and 3 of Table 1. For comparison, the measurement result by the micro loop antenna excitation (Loop) which is a conventional method is also described in the table. The relative dielectric constant ε ′ is calculated from the measurement result of the resonance frequency f 0 and the dimension (thickness t) of the resonator, and is shown in Table 1 above.

  As a result, the two measurement results almost coincided, and the feasibility of the measurement method of the present invention could be verified.

It is explanatory drawing which shows an example of the dielectric property measuring method of this invention, (a) is a schematic sectional drawing, (b) is an AA arrow directional cross-sectional view shown to (a). It is explanatory drawing which shows the other example of the dielectric property measuring method shown in FIG. It is explanatory drawing which shows the other example of the dielectric property measuring method of this invention, (a) is a schematic sectional drawing, (b) is a BB arrow directional cross-sectional view shown to (a). It is explanatory drawing which shows the other example of the electrical conductivity measuring method of this invention, (a) is a schematic sectional drawing, (b) is CC sectional view taken on the line of CC shown to (a). It is explanatory drawing of the dielectric property measuring method by the conventional minute loop antenna excitation. It is a measurement result of the frequency response of the cavity resonator by the NRD guide slot excitation of this invention. It is a measurement result of the frequency response of the cavity resonator by the conventional minute loop antenna excitation. It is a measurement result of the frequency response of the cavity resonator by NRD guide slot excitation when sapphire is used as a plate-like dielectric sample. It is a measurement result of the frequency response of the cavity resonator by NRD guide slot excitation when LTCC is used as a flat dielectric sample.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Upper side flat conductor 11 ... Input side slot 12 ... Output side slot 2 ... Lower flat plate conductor 3 ... Input side NRD guide 4 ... Output side NRD guide 5 ... Cut off Wall 6... Resonator 61 .. Conductor plate 62.. Flat dielectric sample 63.. Conductor wall 64.. Cylindrical dielectric sample

Claims (4)

A pair of dielectric strips are sandwiched between the upper and lower planar conductors so that the tips are close to each other to form an input side and output side NRD guide,
An input side slot and an output side slot are formed on the top ends of the dielectric strips of the input side and output side NRD guides with respect to the upper plate-shaped conductor, respectively, and between the tips of the pair of dielectric strips, the input side A barrier wall made of a conductor is provided so as to extend over the upper and lower planar conductors at equidistant positions in the extending direction of the dielectric strip from the side and output side slots, respectively;
A conductor plate is arranged so as to cover the input side and output side slots in parallel to the upper plate conductor, and a dielectric sample is arranged between the conductor plate and the upper plate conductor, and the input side and Configure a resonator between the output slots,
Dielectric characteristic measurement characterized in that the TE mode of the resonator is excited to measure the resonance frequency and no-load Q of the resonator, and the dielectric characteristic of the dielectric sample is obtained from the resonance frequency and the no-load Q. Method. 2. The dielectric property measuring method according to claim 1, wherein a cavity resonator is formed between the upper flat conductor and the conductor plate. A pair of dielectric strips are sandwiched between the upper and lower planar conductors so that the tips are close to each other to form an input side and output side NRD guide,
An input side slot and an output side slot are formed on the top ends of the dielectric strips of the input side and output side NRD guides with respect to the upper plate-shaped conductor, respectively, and between the tips of the pair of dielectric strips, the input side A barrier wall made of a conductor is provided so as to extend over the upper and lower planar conductors at equidistant positions in the extending direction of the dielectric strip from the side and output side slots, respectively;
A conductor plate is disposed so as to cover the input side and output side slots in parallel with the upper plate conductor, and a resonator is configured between the input side and output side slots,
A method for measuring conductivity, comprising: exciting the TE mode of the resonator to measure the resonance frequency and no-load Q of the resonator, and obtaining the conductivity of the conductor plate from the resonance frequency and no-load Q. . 4. The conductivity measuring method according to claim 3, wherein a cavity resonator is formed between the upper flat conductor and the conductor plate.

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