DD139468A1 - METHOD AND MEASURING CONVERTER FOR MEASURING THE COMPLEX DIELECTRICITY CONSTANT OF SINGLE - SIDED METALLIZED DIELECTRIC PLATES WITH THE HELP OF DIELECTRIC RESONATORS - Google Patents

Abstract

The plate to be examined is so on a dielectric Resonator launched that its resonant frequency is changed and from the frequency shift to be measured and the plate thickness the dielectric constant can be closed. By the proposed use of the Eo -j vibration type is achieved that the field distribution used in the measurement in the plate largely corresponds to the one used in the use of such plates occurs as a substrate for stripline circuits. It is located the plate is in a region of maximum electric field strength. Non-ideal surfaces of the resonator and the one under investigation Plates are an occasion for an air gap between the two and thus for a corruption of the measurement result. With the help of a proposed Three-point Aufläge the plate on the resonator, its influence in the calculation of the dielectric constant from the measured values be taken into account.

Description

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Method and transducer for measuring the complex dielectric constant of single-sided metallized dielectric plates by means of dielectric resonators

Field of application of the invention

The invention relates primarily to the determination of the complex dielectric constant of one-sided metallized substrate plates, as they are required as semi-finished for the production of stripline circuits of various types in the high and ultra-high frequency range and where the knowledge of the complex dielectric constant and thickness for dimensioning the circuit parts and line sections is required , In addition to the average value measured over a complete substrate plate, it is also of interest to possibly measure the variation of the dielectric constant (inhomogeneity) over which the surface area should be averaged, and to measure the deviation of the dielectric constant of different substrate plates in the sense of a production control that of a comparison plate. In addition, the invention is applicable to the measurement of the complex dielectric constant of almost any plate-shaped Dielectric DUTs that rest on a well-conductive layer or plate.

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Characteristic of the known technical solutions

The measurement of the dielectric constant of plate-shaped dielectrics, in particular of substrate plates for stripline circuits, takes place mainly according to the following variants:

1. Production of a cavity resonator filled with the unknown dielectric by metallizing a suitably dimensioned sample on all sides and determining the average dielectric constant from the values to be measured resonance frequency and geometric dimensions.

2. Applying a resonant stripline structure on a one-sided metallized substrate plate, wherein from dimensions and resonant frequency (s) is close to the effective dielectric constant.

3. Applying a plate-shaped sample (which need not be metalized one-sided) to the coupling opening of a resonator or to the open end of a line to close from the measurement of the resonant frequency change of the resonator or the Eingangsscheinwiderstandes or the reflection factor of the line to the sought dielectric constant is.

4. inserting a plate-shaped, non-metallized dielectric sample into the gap of a divided dielectric resonator, wherein from the measured resonant frequency change of the Hq ₁ .Schungsungsmode is closed on the sought dielectric constant,

Disadvantages of these variants are

- the necessary preparation of special measuring samples (1. and 2.) or

the fact that field distributions are used in the measurement

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are not sufficiently well correspond to the field distribution occurring in the practical use of the substrate (3. lind 4.), so that any anisotropies may lead to errors or

- The relatively low coupling and thus. Display sensitivity in the coupling to such z. B. cavity resonators that allow a desired field distribution.

In the proposed solution, no special treatment of the test samples is required, and the field distribution used in the measurement corresponds largely to the practical application, an adequate sensitivity of the display is ensured.

Object of the invention

The invention has for its object to provide a transducer and a matching method, with which it is possible to measure the complex dielectric constant and its location dependence or its deviation from a reference value on one-sided metallized dielectric plates.

According to the invention this object is achieved in that the one-sided metallized, plate-shaped sample is coupled to a dielectric resonator, that the metallized side forms the one conclusion of the resonant system and the dielectric to be examined in a region of maximum longitudinal electric field strength E (see Figure 1 ) is located. As a relatively simple and therefore suitable vibration type, the Eq _1. Mode can be used. The field profile thus generated in the dielectric to be examined largely corresponds to the practical application. In a manner known in principle and according to various variants, it is then possible to deduce the desired dielectric constant from the change in the resonant frequency of the Eq ₁₁ mode of the overall system compared with the case of an applied metal plate, given a known thickness of the substrate.

Not quite avoidable in practical applications

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The air gap between the dielectric resonator and the sample leads to fluctuations in the resonance frequency, depending on the quality of the surfaces involved. This disadvantage can be alleviated or eliminated by introducing a known air gap which can be included in the calculation with the aid of three small elevations of defined height on the dielectric resonator in such a way that a clear, tilt-free support of the substrate on the resonator is made possible.

The calculation of the relationship between the resonant frequency and the dielectric constant is done in a manner known in principle with the approximations usual in such field theory problems. The same applies mutatis mutandis to the dimensioning of the resonator and the compromises to be entered.

embodiment

The invention will be explained in more detail below using an exemplary embodiment. The accompanying drawing shows a schematic diagram of the resonator and the test sample. On a on a conventional substrate (4) with metallization (1) located stripline (5) is a dielectric resonator (3) z. B .. loosely coupled as line discontinuity. With a suitable choice of its dielectric constant and its dimensions, the Eq ₁₁ oscillation mode is excited, whose electric field lines are indicated by (6). The substrate to be examined (2) with the metallization (1) is placed in the manner shown on the resonator. The indicated elevations on the resonator determine the mentioned defined air gap, the connection of the arrangement to a known measuring circuit for detecting the resonance frequency via the strip line (5).

Claims (2)

-S- 207577 claim for invention Method for measuring the dielectric constants of dielectrically metallised dielectric plates with the aid of dielectric resonators, characterized in that the E ₀₁₁ oscillation mode is excited in a suitable dielectric resonator (3), the single-sided metallized plate to be examined in the one sketched in FIG Is placed on the dielectric resonator and is closed from the measured resonance frequency change against the Pail an applied metal plate on the sought dielectric constant. 2. A transducer according to item 1, characterized in that for maintaining a defined air gap between the dielectric resonator (3) and the plate to be examined (2) three small defined elevations of dielectric mounted on the dielectric resonator and as support points for the plate (2) be used. Jiieizu / \ page drawing