Table of Contents
Advertisement
HP 85027A/B/C Performance Tests
Below 2 GHz:
3.
On the HP 8350B set the START and STOP frequencies to the frequencies on the
first line of Table 4-1, Directivity Performance Test Record.
4.
Perform a short/open calibration by pressing [CAL] on the HP 8757A and then
following the prompts on the CRT.
5.
Attach the fixed load to the test port of the HP 85027. On the analyzer, press
[CURSOR] and softkeys [CURSOR ON] and [MAX] to find the point of minimum
return loss (the high point on the trace). Record the displayed CURSOR value on
the appropriate line of Table 4-1. Note that this value represents the scalar sum of
directivity signals (the desired measurement plus signals reflected from the fixed
load (undesired error). Thus fixed load quality directly affects the quality of
directivity measurements.
MEASURED
VALUE
Directivity
(p)
(dB)
30.6
.030
31.1
.028
31.7
.026
32.4
.024
33.2
.022
34.0
.020
34.9
.018
35.9
.016
37.1
.014
38.4
.012
40.0
.010
41.9
.008
44.4
.006
48.0
.004
54.0
.002
co
0
10
03
60
54
50.5
48
46
44.4
43.1
42
40.9
40
SPECIFIED p OR RETURN LOSS OF LOAD
Ip)
Return Loss
(dB)
Figure 4-2. Probable Range of Measurable Directivity Values
6. Refer to Figure 4-2. The shaded areas in this figure represent the probable range
of measureable values for each of the three specified directivity values: 34 dB, 36
dB and 40 dB. On the horizontal axis, locate the fixed load's reflection coefficient
or its specified return loss (convert from SWR if necessary). Move up from this
point to the upper limit of the shaded area between the appropriate diagonal lines.
Allowing for load error, any directivity measurement that falls below this upper
limit indicates with 90% probability that the HP 85027 is within specifications. If
4-3
Advertisement
Table of Contents
