Millimeter wave measurement process

Details Millimeter wave measurement process Millimeter wave measurement process

1995-12-29

2001-07-03

Nguyen, Vinh P. (Department: 2858)

Electricity: measuring and testing

Impedance, admittance or other quantities representative of...

Distributive type parameters

C324S636000, C324S632000, C324S071600

Reexamination Certificate

active

06255831

ABSTRACT:

The invention relates to a millimeter wave measurement process.
From H.-G. Unger, Elektromagnetische Theorie für die Hochfrequenztechnik [Electromagnetic Theory for High-Frequency Technology], Hüthig 1981, it is known that with quality measurements (Vol.1, Eq. 3.75 and Eq. 3.77) and resonant frequency measurements (Vol. 2, Eq.9.17) in cavity resonators, the surface impedance Z
ob
=R
ob
+jX
ob
can be determined. Furthermore, it is also known from H.-G. Unger that in a cavity resonator, an infinite number of vibrational modes is possible, regardless of the particular shape (Vol. 2, p. 269).
As T. Kuhlemann and J. H. Hinken explain in “Computer-Controlled System for Surface Resistance Measurements of HTc Superconducting Films”, IEEE Transactions on. Instrumentation and Measurement, Vol. 40, No. 3, June 1991, pp. 539-543, this is also possible with high temperature superconducting films.
Furthermore, German patent disclosure DE 42 04 369 C2 and international patent disclosure WO 94/04935 A1 disclose processes for quality determination of high temperature superconducting films.
In the known measurement processes, though, only the average values {overscore (R
ob
+L )} and {overscore (X
ob
+L )} are recorded, which are given by:
R
_
0
⁢
b
=
∫
R
0
⁢
b
⁢
&LeftBracketingBar;
H
t
&RightBracketingBar;
2
⁢
ⅆ
a
/
∫
&LeftBracketingBar;
H
t
&RightBracketingBar;
2
⁢
ⅆ
a
⁢
 
⁢
and
X
_
0
⁢
b
=
∫
X
0
⁢
b
⁢
&LeftBracketingBar;
H
t
&RightBracketingBar;
2
⁢
ⅆ
a
/
∫
&LeftBracketingBar;
H
t
&RightBracketingBar;
2
⁢
ⅆ
a
⁢
 
These measurement data can only be used if {overscore (R)}
ob
≈{overscore (R)}
ob
({right arrow over (r)}) and {overscore (X)}
ob
≈{overscore (X)}
ob
({right arrow over (r)}) at each point {right arrow over (r)}.
If the surface impedance, though, is location dependent, then if need be, the average value functions {overscore (R)}
ob
({right arrow over (r)}) and {overscore (X)}
ob
({right arrow over (r)}) can be determined by measurements at various places {right arrow over (r)} on the surface. In actual practice, this is very disadvantageous since surface defects which are significant, but small in area are not detected. In very expensive surfaces, such as high temperature superconducting films, this fact is of particular significance. Since films of this kind are comprised of a plurality of elements, such as yttrium, barium, copper, and oxygen, regions with increased losses can appear within large-area coatings. If only the average value functions {overscore (R)}
ob
({right arrow over (r)}) and {overscore (X)}
ob
({right arrow over (r)}) are used for quality assurance, either regions of this kind are not detected or large areas of these places have to be discarded. If such defective half-finished products are released for the manufacture of components, for example microwave filters, only later do these undetected regions cause component malfunctions, which brings about considerable additional costs.
If on the other hand, places with unacceptable quality are detected, large-area regions in their vicinity must be discarded. As a result, valuable usable material is wasted; there is an increased environmental impact and a substantial increase in cost.
The object of the invention, therefore, is to create a millimeter wave measurement system, which makes it possible to determine the surface impedance exactly in three-dimensional terms Z
ob
({right arrow over (r)})=R
ob
({right arrow over (r)})+j X
ob
({right arrow over (r)}).
According to the invention, this object is attained by a millimeter wave measurement system as defined by the body of claim
1
.


REFERENCES:
patent: 4885527 (1989-12-01), Lacombe
patent: 5440238 (1995-08-01), Martens
patent: 5506497 (1996-04-01), Klein
patent: 5563505 (1996-10-01), Dorothy
patent: 5594351 (1997-01-01), Hearn
patent: 42 04 369 (1993-09-01), None
patent: 94/04935 (1994-03-01), None
Unger, H.-G., “Elektromagnetische theorie fur die Hochfrequenztechnik (Electromagnetic theory for High-Frequency Technology)”, Huthig, pp. 229-274 (1981).
Kuhlemann, Thorsten et al., “Computer-controlled system for surface resistance measurements of HTcSuperconducting Films”, IEEE Transaction on Instrumentation and Measurement, vol. 40, No. 3, pp. 539-543 (Jun. 1991).

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