TB 9-5985-314-35
c. Unless otherwise specified, verify the result of each test and, whenever the test
requirement is not met, take corrective action before continuing with the calibration. Omit
steps for parameters listed in Appendix A with the statement N/A.
7. Definitions.
Explanation of
terms peculiar to
directional couplers are listed in
a
through d below to ensure accurate interpretation of the measurement techniques used in
this procedure.
a. Nominal Coupling. The nominal loss between the primary input port and the
auxiliary side arm port, with the output port terminated, is called coupling. Normally
coupling is expressed in dB.
b. Coupling Variation. The maximum average deviation from the coupling value
resulting from manufacturing process, is called coupling variation and is normally
expressed in dB.
c. Frequency Sensitivity. The allowable deviation from the average coupling value
(coupling variation), resulting from the frequency characteristics of a directional coupler, is
called frequency sensitivity and is normally expressed in dB.
d. Directivity. The
difference between the
coupling value (in
dB) and the
insertion
loss (isolation) (in dB) measured between the output port and side arm port (reverse
direction) with the input port terminated is called directivity and is expressed in dB.
a. Use Appendix A to
determine TI
parameters as
listed in
(1) through (5) below:
(1) Frequency range.
(2) Coupling value.
(3) Coupling variation.
(4) Frequency sensitivity.
(5) Directivity.
b. Select appropriate equipment setup for TI
frequency range from figures as
listed in
(1) through (3) below:
c. Determine and record a minimum of 10 evenly spaced test frequencies over the TI
entire frequency range.
d. Connect equipment as shown in figures 1, 2, or 3 and allow 1 hour for equipment
warm-up for figure 1 (3 hours for figures 2 and 3).