JP2002271278A - Measurement system for mutual modulation distortion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement system for mutual modulation distortion capable of measuring a mutual modulation distortion generated in a contact part between metal materials with little labor, in a short time, at small cost, and accurately. SOLUTION: A plane contact device is prepared by providing a conductor pattern having contact conductor parts formed with a metal material to be measured on the surface of flat dielectric substrates, respectively. A first planar contact device is connected to a mutual modulation distortion measuring circuit via a noncontact connector, and a second plane contact device is superimposed on the first planar contact device so that the contact conductor part thereof comes into contact with the contact conductor part of the first plane contact device. Further, the second planar contact device is connected to a dummy load via a second noncontact connector, for measuring a mutual modulation distortion depending on a contact of the contact conductor parts of conductor patterns of the first and second plane contact devices.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for simply and accurately measuring intermodulation distortion generated at a contact point between metallic materials.

[0002]

2. Description of the Related Art In various communication systems, there is a problem of intermodulation distortion due to interference between two signals having different frequencies. For example, an antenna used in a mobile communication base station is used for both transmission and reception. Since the transmission frequency and the reception frequency are different, intermodulation distortion between them becomes a problem, and In some cases, noise due to distortion interferes with the reception band and communication becomes impossible. Conventionally, in such a mobile communication system, various studies have been made on suppression of intermodulation distortion in an active circuit such as an amplifier, and considerable results have been obtained. However,
No effective countermeasures have been taken for the intermodulation distortion generated in the passive circuit portion. The passive circuit portion may be a contact surface between metal materials, for example, a connector, an antenna, an antenna peripheral member such as an antenna mounting bracket, or the like.

FIG. 1 shows locations where intermodulation distortion occurs around an antenna in a base station of a mobile communication system. A transmitting antenna 12 and a receiving antenna 13 are installed in a tower 11 of a base station, and an antenna element array 14 in which a large number of antenna elements are arranged is provided inside these antennas. It is connected to an antenna input / output terminal 16 via a beam control device 15 for directing a beam in a predetermined direction. FIG.
Is an example in which a printed dipole antenna is used as an element of the antenna element array 14, and the printed circuit board 17
Are formed according to a predetermined pattern, and two reflectors 19 are provided so as to be substantially orthogonal to the printed board 17. These printed boards 17 and the reflectors 19 are arranged inside a cylindrical cover 20. Have been. In such a configuration, a connection point between the feed circuit of the antenna element row 14 and the beam control device 15, a conductor connection position inside the beam control device 15, a connection position between the antenna input / output terminal 16 and the coaxial cable 17, an antenna Intermodulation distortion occurs in the fittings for attaching the substrates 12 and 13 to the tower 11 and at the contact points between the two reflectors 19.

Investigation of the occurrence of intermodulation distortion around the antenna in the base station of the above-described mobile communication system reveals that there is a contact interface between a metal material and a metal material. Conventionally, such intermodulation distortion at the metal contact interface has not been a serious problem, but as the frequency becomes higher and the signal electric field becomes weaker, the intermodulation distortion noise due to the nonlinear characteristics of the metal contact interface increases. The impact is becoming a problem.

Particularly, in a mobile phone base station, an antenna is commonly used for transmission and reception, and a plurality of these antennas may be installed adjacent to each other. Intermodulation distortion noise has become an important issue. Especially in mobile phone base stations,
The reception power is smaller than the transmission power, the received signal electric field becomes extremely weak, the influence of the intermodulation distortion noise becomes relatively large, and if the intermodulation distortion noise enters the reception band, the reception may not be possible. is there.

[0006]

As a method of suppressing the intermodulation distortion generated at the contact interface between the metal materials as described above, first, it is conceivable to eliminate the contact interface. However, when actually building a mobile phone base station,
Eliminating contact between metallic materials is limited and impractical. In addition, since intermodulation distortion occurs between the same type of metal materials due to the difference in the surface state of the contact portion, the intermodulation distortion cannot be eliminated even if the conductor is formed of the same metal material.

The next solution is to increase the contact area and increase the contact pressure to reduce the current density. However, since the base station itself is required to be small and light, there is a limit in increasing the contact area between the metal materials, and this is not a practical solution. For example, a coaxial connector is used to connect to a coaxial cable, and as this coaxial connector, a DIN connector that generates less intermodulation distortion is generally used, but a large size and a small size are required. .

As a third solution, it is conceivable to improve the surface condition of a contact portion between metal materials to suppress the occurrence of intermodulation distortion. For example, by optimizing the base metal, plating material, surface roughness, and the like, it is expected that the occurrence of intermodulation distortion can be effectively suppressed without excessively increasing the contact area and contact pressure.

However, in order to improve the surface condition of the contact portion between the metal materials as described above, the type of the underlying metal,
Prototype of many coaxial connectors by changing various parameters such as plating material type, film pressure, surface roughness, etc.
They must be used to measure intermodulation distortion, which requires a great deal of labor, time, and cost for trial production. In addition, there are many uncertain factors such as variations in processing accuracy of the coaxial connector and deterioration of characteristics due to attachment / detachment, and there is a problem that accurate measurement of intermodulation distortion is difficult.

When using a coaxial connector,
It is necessary to solder between the connector and the coaxial cable, and the work is troublesome, and since the soldering condition of each coaxial connector is not uniform, the occurrence of intermodulation distortion at this contact part The situation greatly affects the measurement, and there is also a problem that only the intermodulation distortion which is originally required to be measured and which is generated at the contact point between the connectors cannot be accurately measured.

Therefore, an object of the present invention is to reduce intermodulation distortion generated at a contact portion between metal materials with a small amount of effort.
It is an object of the present invention to provide an intermodulation distortion measurement system capable of performing accurate measurement in a short time at low cost.

[0012]

SUMMARY OF THE INVENTION An intermodulation distortion measuring system according to the present invention comprises a contact conductor, a connection conductor made of a metal material on one surface of a flat dielectric substrate, and the contact conductor and the connection conductor. A plurality of planar contact elements having a conductor pattern having a relay conductor section connecting the first planar contact element and a ground plane formed on the other surface, and connecting the connection conductor section of the first planar contact element to the first non-contact area. The first planar contact element is connected to the intermodulation distortion measuring circuit via a connector, and the second planar contact element is connected to the first planar contact element such that the contact conductor thereof contacts the contact conductor of the conductor pattern of the first planar contact element. With the element
Connecting the connection conductor of the conductor pattern of the planar contact element to the dummy load via the second non-contact connector,
The intermodulation distortion based on the contact of the contact conductor of the conductor pattern of the first and second planar contact elements is measured.

In such an intermodulation distortion measuring system according to the present invention, a planar contact element having a conductor pattern formed of a metal material to be measured on the surface of a flat dielectric substrate is used. Is
For example, it can be manufactured using a printed wiring board, so that the labor, time, and cost required for manufacturing a sample are significantly reduced, the variation in processing accuracy is reduced, and the characteristic is deteriorated due to attachment and detachment. Since there is no intermodulation distortion measurement accuracy, the accuracy is improved. Furthermore, when connecting this planar contact element to the intermodulation distortion measuring circuit and the dummy load, a non-contact connector is used, so that the soldering work as in the related art becomes unnecessary, and
The measurement error due to the change in the soldering state is not mixed, and the intermodulation distortion can be measured very accurately.

In implementing the intermodulation distortion measuring system according to the present invention, the first and second non-contact contacts are respectively connected to the intermodulation distortion measuring circuit and the dummy load via a coaxial cable having an impedance of 50Ω. Although the connection is made, if the contact conductor of the planar contact element is formed so as to match with the resistance of 50Ω, the width is reduced to several millimeters or less, but in consideration of measurement accuracy, the width is set to 5 millimeters or more. Is preferred. However, when formed in this manner, the impedance of the contact conductor portion becomes small, and the impedance does not match with the coaxial impedance of 50Ω. Therefore, in a preferred embodiment of the planar contact element according to the present invention, the width of the contact conductor is increased, and the relay conductor connecting the contact conductor and the connection conductor is connected to the impedance of the wider contact conductor. An impedance transformer for matching the impedance of the conductor is formed.

Further, when implementing the intermodulation distortion measuring system according to the present invention, the first and second non-contact connectors are arranged parallel to each other with a space substantially equal to the thickness of the planar contact element. A flat dielectric substrate, a third dielectric substrate sandwiched between the first and second dielectric substrates, and first and second planar contact elements on the outer surface of the first dielectric substrate. When the leading end of the third dielectric substrate is inserted into the space between the two dielectric substrates so as to be separated from the leading end of the third dielectric substrate by a predetermined distance, it is aligned with the extending direction of the connection conductor. A conductive strip formed so as to extend, a conductive film formed on the entire outer surface of the second dielectric substrate, and a third dielectric substrate facing the first dielectric substrate On the surface, outside the first dielectric substrate It is composed of a conductor strip formed so as to extend in alignment with the extending direction of the conductor strip formed on the surface and a conductive film formed on the entire opposite surface of the third dielectric substrate. It is suitable.

[0016]

FIG. 3 is a block diagram showing the configuration of the entire intermodulation distortion measuring system according to the present invention. Measuring unit 21 including first and second planar contact elements forming a contact between metal materials whose intermodulation distortion is to be measured
To the duplexer 2 via the first non-contact connector 22.
3 and to the dummy load 25 via the second non-contact connector 24. In this example, a semi-rigid coaxial cable having a length of 50 m is used as the dummy load 25.

The duplexer 23 is connected to a power combiner 26, which is connected to first and second wave sources 27 and 28. These first and second wave sources 27 and 28 are composed of standard signal generators 29 and 30 and power amplifiers 31 and 32 having frequencies of f ₁ and f ₂ , respectively.
Further, the duplexer 23 is connected to an intermodulation distortion measuring circuit 36 having a bandpass filter 33 for extracting an intermodulation distortion component, a low noise amplifier 34, and a spectrum analyzer 35.

FIG. 4 is a perspective view showing a detailed configuration of the measuring unit 21 including the first and second planar contact elements, and the first and second non-contact connectors 22 and 24. First and second planar contact elements 41 and 4
2 is almost the same, the first planar contact element 41 connected to the duplexer 23 via the first non-contact connector 22 will be described. The first planar contact element 41 is constituted by a printed circuit board. For example, one of the flat surfaces of a dielectric substrate 43a formed of tritetrafluoroethylene (trade name: Teflon) or a dielectric material having a relative dielectric constant of about 2.6 has a contact conductor portion 44a and a connection conductor portion 45a. And a conductor pattern including a relay conductor portion 46a connecting between the contact conductor portion and the connection conductor portion, and a ground plate 47a made of a metal film is formed on the entire other surface.

The second planar contact element 42 is formed in the same manner, and the corresponding parts are represented by the same reference numerals with the addition of b. When measuring the intermodulation distortion, the contact conductor portions 44a and 44b of the first and second planar contact elements 41 and 42 are overlapped so as to contact each other at a predetermined pressure, so that the surface condition of these contact conductor portions and The occurrence state of the intermodulation distortion due to the contact pressure can be measured.

In the present invention, the contact between the metal materials whose intermodulation distortion is to be measured is realized by bringing the first and second planar contact elements 41 and 42 made of a flat printed circuit board into contact. There is no need to prototype and measure a complicated coaxial connector as in the prior art. Therefore, a test sample can be easily and inexpensively manufactured in a short time. In addition, the accuracy of manufacturing the measurement sample is improved, and the influence of the variation on the measurement accuracy of the intermodulation distortion is extremely small, so that accurate measurement can be performed.

Further, in the present invention, the first planar contact element 41 is connected to the first and second wave sources 27 and 28 via the duplexer 23 and the intermodulation distortion measuring circuit 36.
The first and second non-contact connectors 22 and 24 are used to connect the second planar contact element 42 to the dummy load 25 and connect the measurement sample to the intermodulation distortion measurement circuit and the dummy load. The operation is simplified, and no intermodulation distortion is generated at these contact points.

FIG. 5A is a perspective view showing a detailed configuration of the first non-contact connector 22, and FIG. 5B is a cross-sectional view showing a part of the first non-contact connector 22 in an enlarged manner. Second non-contact connector 24
Of the first non-contact connector 2
2 will be described. The non-contact connector 22 includes first and second flat dielectric substrates 51a and 52a arranged in parallel with each other with a space substantially equal to the thickness of the planar contact element 41, and the first and second dielectric substrates 51a and 52a. And a third dielectric substrate 53a sandwiched between the body substrates. In this case, the third dielectric substrate 53a
The tip is inserted slightly before the intermediate position between the first and second dielectric substrates 51a and 52a. These first to third dielectric substrates 51a, 52a and 53a can be formed of a dielectric material having a relative dielectric constant of 2.0 to 3.0, for example.

The planar contact element 41 is provided on the first and second dielectric substrates 51 a and 5 of the non-contact connector 22.
In the space between 2a, the tip is inserted to a position slightly before the intermediate position of these dielectric substrates. Therefore, when the planar contact element 41 is inserted,
The tip will be spaced from the distal end of said third dielectric substrate 53a by a predetermined distance d _1. This separation distance d ₁
Can be, for example, about 1 mm. The length d of the first and second dielectric substrates 51a and 52a
₂ is 156 mm in this example.

A conductor strip 54a is formed on the outer surface of the first dielectric substrate 51a so as to extend in alignment with the extending direction of the connection conductor 45a when the planar contact element 41 is inserted. I do. Further, a conductor film 55a is formed on the entire outer surface of the second dielectric substrate 52a. Further, a conductor strip 54a formed on the outer surface of the first dielectric substrate is provided on the surface of the third dielectric substrate 53a facing the first dielectric substrate 51a.
Conductor strip 5 so as to extend in alignment with the extension direction of
6a, and a conductor film 57a is formed on the entire back surface.

The first non-contact connector 22 is connected to the duplexer 23 via a coaxial cable 61. As shown in FIG. 5B, a conductive strip formed on one surface of the third dielectric substrate 53a 56a is connected to the core wire 62 of the coaxial cable 61 by solder 64, and the conductor film 57a formed on the other surface is connected to the shield 6 of the coaxial cable.
3 is connected by solder 65. Although the non-contact connector 22 and the coaxial cable 61 are directly connected as described above, the planar contact elements 41, 4
Even if you exchange 2, this connection can be left as it is,
This connection state does not affect the intermodulation distortion measurement. The configuration of the second non-contact connector 24 is also substantially the same as that described above. In FIG. 4, the corresponding parts are indicated by the same reference numerals with the addition of b. However, no stub is formed on the conductive strip 54a formed on one surface of the first dielectric substrate 51a of the first non-contact connector 22, but the first dielectric of the second non-contact connector 24 is not formed. Substrate 5
The difference is that a stub 54c (see FIG. 4) is formed on the conductive strip 54b formed on one surface of the first strip 1b.

FIG. 6 shows the input characteristics of the non-contact connector 22 described above, and the ratio band 17 of 0.84 GHz to 0.99 GHz.
%, The reflection loss is -20 dB or less in a wide frequency range. Also, the insertion loss is as small as 0.2 dB or less.
Therefore, for example, when the transmission frequencies are set to 862 MHz and 887 MHz, the fifth-order intermodulation distortion generated at 937 MHz can be effectively used. Here, it goes without saying that the correlation modulation distortion of other orders such as the third and seventh orders can also be measured.

In the present invention, a planar contact element in which the metal material and the surface condition of the contact conductor are variously changed is manufactured using a printed wiring board, and two planar contact elements 41 selected from these are selected. As shown in FIG. 4, the contact conductors 42a and 44b are overlapped so that the contact conductors 44a and 44b are in contact with each other, and the contact pressure at that time can be adjusted. Further, these planar contact elements 41,
42, the first of the non-contact connectors 22 and 24, respectively.
By inserting between the second dielectric substrates 51a and 52a and connecting to the intermodulation distortion measuring circuit 36 and the dummy load 25, intermodulation distortion can be measured.

In this case, the planar contact elements 41, 4
2 and the measurement circuit and the dummy load 25 do not need to be connected by soldering as in the prior art, so that the connection work is extremely simplified, and a measurement error due to a change in the soldering state is eliminated. Can be measured very accurately.

The present invention is not limited to the above-described embodiment, and many modifications and variations are possible. For example,
In the above-described embodiment, the impedance transforming portion is provided in the relay conductor portion in order to eliminate the impedance mismatch caused by increasing the width of the contact conductor portion of the planar contact element. However, when the width of the contact conductor portion is set to 50Ω. Need not be provided with such an impedance transformer. further,
The configuration of the non-contact connector is not limited to the above-described embodiment, and any configuration may be used as long as the flat planar contact element can be detachably connected to the measurement circuit or the dummy load in a non-contact manner. Good.

[Brief description of the drawings]

FIG. 1 is a diagram showing locations where intermodulation distortion occurs in a mobile communication base station.

FIG. 2 is a diagram showing locations where intermodulation distortion occurs in the antenna.

FIG. 3 is a block diagram showing the overall configuration of an intermodulation distortion measurement system according to the present invention.

FIG. 4 is a perspective view showing a detailed configuration of the planar contact element.

FIGS. 5A and 5B are a perspective view and a sectional view, respectively, showing a detailed configuration of the non-contact connector.

FIG. 6 is a graph showing input characteristics of a non-contact connector.

[Explanation of symbols]

21 measuring unit, 22, 24 non-contact connector,
23 duplexer, 25 dummy load, 2
6 power combiner, 27, 28 wave source, 29, 30 standard signal generator, 31, 32 power amplifier, 33 band pass filter, 34 low noise amplifier, 35 spectrum analyzer, 36 intermodulation distortion measurement circuit,
41, 42 first and second planar contact elements, 4
3a, 43b Dielectric substrate, 44a, 44b Contact conductor, 45a, 45b Connection conductor, 46a, 46
b relay conductor part, 47a, 47b ground plane, 51a,
52a, 53a first to third dielectric substrates, 54a,
56a conductor strip, 55a, 57a conductor film,
61 Coaxial cable

Continued on the front page F-term (reference) 5J046 AA03 AB07 TA03 5K042 AA06 CA02 CA13 CA23 DA03 DA14

Claims (4)

[Claims] 1. A conductor pattern having a contact conductor, a connection conductor, and a relay conductor connecting between the contact conductor and the connection conductor made of a metal material on one surface of a flat dielectric substrate. Forming a plurality of planar contact elements having a ground plane formed on the other surface, connecting a connection conductor of the first planar contact element to an intermodulation distortion measuring circuit via a first non-contact connector, The second planar contact element is overlapped with the first planar contact element such that its contact conductor contacts the contact conductor of the conductor pattern of the first planar contact element, and the conductor of the second planar contact element is Connect the connecting conductor of the pattern to the second
Intermodulation distortion measurement system for measuring intermodulation distortion based on contact of a contact conductor portion of a conductor pattern of a first and second planar contact element by connecting to a dummy load through a non-contact connector of the first aspect of the invention. . 2. The intermodulation distortion measuring system according to claim 1, wherein the planar contact element is manufactured using a printed wiring board. 3. The impedance of the contact conductor having a wider width and the connecting conductor are provided on the relay conductor for connecting the contact conductor and the connection conductor, wherein the width of the contact conductor of the conductor pattern of the planar contact element is increased. The intermodulation distortion measuring system according to claim 1 or 2, wherein an impedance transformation unit for matching impedance of the unit is formed. 4. A first and second flat dielectric substrate in which said non-contact contacts are arranged in parallel with each other with a space substantially equal to the thickness of said planar contact element, and said first and second flat dielectric substrates. A third dielectric substrate sandwiched between dielectric substrates, a planar contact element on an outer surface of the first dielectric substrate, a space between the first and second dielectric substrates, A conductor strip formed so as to extend in alignment with the extending direction of the connection conductor when inserted so as to be separated from the tip of the third dielectric substrate by a predetermined distance; A conductive film formed on the entire outer surface of the dielectric substrate;
A conductor strip formed on a surface facing the first dielectric substrate so as to extend in alignment with an extending direction of the conductor strip formed on the outer surface of the first dielectric substrate; The intermodulation distortion measuring system according to any one of claims 1 to 3, further comprising: a conductive film formed on the entire opposite surface of the dielectric substrate.