DRAFT Recommended Practice for Measurements and ...

1/29/98 100 C95.3-1991 Revision — 2 nd Draft
10/98 Draft
Fig A1 Open Parallel Plate Calibration System
NOTES:
(1) Top and bottom are metal clad plywood
(2) Vertical supports are wood 2 X 4s
(P) Location P is the optimum calibrating point
A2. Open Parallel Plates
Figure A1 is a sketch of a system using open parallel plates to generate a known electric
field at frequencies up to about 30 MHz. The expression for calculating the
E-field existing between two flat conducting plates is the same as that for a TEM cell,
namely
E = V/b (V/m) (Eq A1)
where E is the electric field strength, V is the voltage difference between plates and b is
the plate spacing. The uncertainty of the field level is the same as that for a TEM cell.
The wave impedance is greater than 377 Ω, similar to that of an unterminated TEM cell.
Therefore, a larger E-field can be produced for a given RF input. If the line is made
resonant by means of an inductor, larger field strengths can be produced, but more care
must be taken to ensure the accuracy of calibration. In the example of Fig A1, an E-field
of 1000 V/m can generally be achieved with a 1 W power source.
Fig A2 Parallel-Plate Transmission Line for Generating E- and H-fields,
f = 0.3 - 30 MHz
NOTES:
(1) Top and bottom are metal clad plywood
(2) Vertical supports are wood 2 X 4s
Copyright © 1998 IEEE. All rights reserved. This is an unapproved IEEE Standards Draft,
subject to change.