DE1516978A1 - Arrangement for broadband compensation of the systematic error of two- and four-pole comparators in the high and maximum frequency range - Google Patents

Description

Dr _e -Ing. Uwe Bühn, Dresden VEB Funkwerk Dresden, 806 Dresden, Biesehwitastraße

26th

Dresden, April 4th 1966

Arrangement for broadband compensation of the systematic Errors of two- and four-pole comparators in the high and Maximum frequency area

The invention relates to an arrangement that allows the with two- and four-pole comparators occurring systematic Eliminate coupling problems «This comparator * !! work with rotatable inductive loops · Each of these loops is arranged over a coaxial line and can go through Slots that are located in the outer conductor of these coaxial lines create a voltage in the inner conductor of the coaxial lines when induce a current through the inductive loop flows · By suitable construction it can be achieved that in all three loops one in amplitude and phase same current flows "

With the same angular position (angle between the loop plane and the inner conductor axis) currents of the same magnitude would arise in the three inner conductors if the coaxial lines are of the same length and terminated in the same way.However, if one line is terminated with a reactance, the second with an effective resistance and the third ζ · Β · with the unknown complex two-terminal network, a pure reactive current flows in the first line, a Wlrkstroa in the second and a complex current in the third. Since all three lines collide in Zweipolaessung at one point, la "three streams connected null indicator add this point dl vectorially · A to this point allows to display the state" zero voltage "tm" Such a condition can be carried Betragsregelustg the three Ströa »Manufacture kit help · of the rotatable inductive loops. The two-pole parameter you are looking for can be determined using the loop positions. The coupling error mentioned is due to the finite atatand between the uncoupling locations of the double loops

caused by the delay point (compensation apuiikt) · To eliminate it is a cumbersome and time-consuming correction calculation necessary "

'There are known arrangements in which the error occurs concentrated capacities is reduced, which in the branch with the active standard (active branch) and in the leading to the Ueßobjekt Branch (measuring branch) are arranged close to the coupling point.

Ss an arrangement is also known in which between the Coupling sor th and the branching point lines are arranged, the length of which is a multiple of half the wavelength of the measuring frequency used « It is also possible to reduce the error, the dimensions of the measuring object used it to be made extremely small The options outlined have the following disadvantages:

1 If the error is compensated by concentrated capacities, it is assumed for the calculation of the capacity that the large

1 <«tan 2it - ~ - (I _{1 a.} Distance between bin

coupling location and branching point, Λ ■ wavelength) linear can be approximated · If this leads to impermissible errors above about 800 MHa su, the capacitance must be variable executed and adjusted when the frequency is changed, odes of the residual error must be taken into account mathematically or neglected

2 · The · earlier proposed · arrangement has the disadvantage that it also requires three variable lines that have to be adjusted at Frequeniweohsel.

3 · Bin · extreme reduction of the geometric dimensions leads to an economically no longer justifiable expense, since tolerances of a few M B must be observed during production ·

The aim of the invention is, without increased manufacturing costs, an arrangement for the belt assembly systematic error of two- and four-pole compssatoses 1 “Heck and Hdchstfsequemife” i “t vessus” nlsgen, dl · without sumttsuchen Bedlsmmgssitfweat eliminates the error,

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so that the correct calculation time required up to now or the Leitmi ^ s- bsw. Adjustment of capacity and the costs for additional cables or for increased manufacturing costs «Saved up; can be and all above Described disadvantages of the state of technology: to be avoided «; /:

In accordance with the invention, the task is solved in that in each branch the length 1 *. between the node and the coupling point and to a length Ig beyond the coupling point, the line impedance has changed from the normal value Zj- to the value Z- ^ q and that the above length 1, + I ₂ between the coupling point and the test object in the case of two-pole comparators is changed to the following described · type is selected. One denotes the one of the comparator branch final conductance with Y, whereby either the unknown conductance Υ _χ , the normal conductance Y ^ or the normal susceptibility + JYj ₁ can be used, the length between the node and the coupling point with I ^ and the am Coupling site induced voltage with Uy so is the current flowing through the indicator from this branch during zero adjustment

honeycomb, 'Λ-ψ i * t.

If one chooses the quantities Z ₁₀ , I ₁ , I ₂ and I _{3 in} such a way that the reactive components in the numerator and denominator of the above equation disappear, then the current is I n ' _g

whereby the conditions are required - below Called dimensioning equations -

nuts be met · iteuait the current difference I only by a real Eaktor "

of the current I ₀ , which would flow with vanishing lengths I ₁ β Ö, I _{2 sr O.}

The beldon meraioning equations contain the four

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Freely selectable parameters I ₁ , I ₂ , I3 and Z ₁₀ . In order for the pair of equations to be solvable, two quantities must be specified in each case »You have a largely free choice, although if you specify 1- and Z ₁ ^ you have to choose such values that I ₁ and I _{2 become} positive. The ones at the transition »Represents a minimum interference capacitance between the normal and the changed wave impedance can either be included in the calculation or compensated by a twist in the inner or outer conductor of the coaxial line occur suddenly or continuously

ifit the proposed arrangement can now be the complex The value can be read immediately on the comparator scales even at the highest frequencies Correction reohnung was based on an approximation method, he. a significant improvement in accuracy is aimed at The previously required idle time is reduced at high Frequencies to around 10% of the time previously required

The idea of the invention is to be explained in more detail below using an exemplary embodiment.

Pig · 1 shows the equivalent circuit of the Ueßsweigee of a two-pole comparator and Fig. 2 a construction example

The inductive coupling loop 1 induces in the one below located coaxial line a voltage U, which is symbolized duroh the source 2. As a result of the unknown Conductance Ix of the letobdektee 3 drives the * voltage U durab the indicator 4 shows a current I of the magnitude

The quantities I ₁ and I _{3 are} given for dimensioning. For this example, I _{1 should be} very small compared to the wavelength. For reasons of practically simple setting, 1 »is chosen so that a course short at the location of the object 3 is transformed as a short at branch point 5. This is with sufficient approximation for Ζ, .Α, Äff (/, ♦ / *) ■

fulfilled · BAD ORSGfNAL

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However, this condition is randomly ₉ so that further size can be freely selected "identical to a Lineärkombinatioii ,, from the two Dimensionierungsgleichungeii * In the present example is I ₂ given and it was followed from the Dimeneiönlerungsgieichungen

if I ₂ «A is chosen»
To simplify matters, 1 ^, I ₂ , I3 and Z ₁₀ are chosen to be the same size in all three branches, so that the adjustment condition is'; ■ '■■■ "■ ;.''""-" ■■■ - ' - -: ';

I β current j.m branch containing X “

Iq s current in the branch of Y ^ contains I _B = current in the branch of JYj ₁ contains index ο: current that would flow at 1 * ₉ I ₂ β ο.

One recognizes that the above borrowing condition applies to all finite ones A-values is fulfilled and therefore no more errors occur An example of the constructive implementation of the JSrsata circuit Pig · 1 is shown in Fig. 2 · The surge in wave resistance is due to a sudden thickening of the Inner conductor 6 has been caused · The in such Interfering capacitance occurring at jumps has been eliminated by a recess 7 at the jump point

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Claims (1)

Claims t Arrangement for broadband compensation de # by the finite distances between the coupling points (2) and the node (5) caused systematic errors of two- and four-pole comparators in the high and maximum frequency range, characterized in that in each branch of the! Comparator on the length I ^ between the node (5) and the Einkopplungeort (2) and for a length I ₂ beyond the Einkoppliingsort (2), the line impedance has the characteristic impedance Z ^ deviating from the normal value Z ^ and that the quantities Zj ₀ , I ^, I. ₂ and the distance 1, -ι- I ₂ between the coupling point (2) and the conductance (4) closing the branch are chosen so that the dimensioning equations for each branch and are fulfilled. 2 · Arrangement according to claim I _9, characterized in that the sizes 1 ^ ₉ I ₂ , 1? and Zy-. are the same in all branches of the comparator 3 "Arrangement according to claim 1, characterized in that the Wave resistance jump caused by a sudden change in the inner and / or outer conductor diameter is· 4, arrangement according to claim 1 and 3, characterized in that that the surge in wave resistance by inserting a Dielectric is caused 5 · Arrangement according to claim 1 $ 3 and 4 », characterized in that the · interference capacitance occurring at the jump point is eliminated by · turning the inner or outer conductor · 6 · Arrangement according to claim 1, characterized in that the transition to the changed wave resistance is continuous he follows· 909846/0304 bathroom