Specifications
30
Power at reference mixer
Calculation of the power level at the reference mixer depends on the method used to
obtain the reference signal. Almost all ranges obtain the reference channel signal using
a stationary reference antenna to receive a portion of the radiated transmit signal.
Select one of the two methods below for your configuration.
1. Radiated reference signals
When using a radiated reference, the power at the reference mixer can be determined
from the following equation:
P
RM
= E
RP
– P
D
+G
REF
–L
1
where P
RM
= Power level at the reference mixer (dBm)
E
RP
= Effective radiated power (dBm)
P
D
= Free-space loss (power dissipation) (dB)
G
REF
= Gain of the reference antenna (dBi)
L
1
= Cable loss between reference antenna and reference mixer (dB)
Caution: P
RM
must not exceed the maximum power level of the mixer
1
P
RM
– Mixer conversion loss
2
must be less than +5 dBm so as to not exceed the 1 dB
compression level for the LO/IF input for the 85309B.
2. Coupled reference signals
When using a coupled reference, the reference channel power level can be determined
by subtracting the cable insertion losses and the coupling factor of the directional
coupler and adding amplifier gain, if any, to the output power of the transmit source.
Power at the test mixer
The power at the test mixer is equivalent to the power at the output of the AUT (calculat-
ed earlier) if the mixer is attached directly to the AUT. The power level at the test mixer
can be determined from the following equation:
P
TM
= E
RP
– P
D
+G
AUT
–L
2
where P
TM
= Power level at the test mixer (dBm)
E
RP
= Effective radiated power (dBm)
P
D
= Free-space loss (power dissipation) (dB)
G
AUT
= Gain of the test antenna (dBi)
L
2
= Cable loss between AUT and test mixer (dB)
Caution: P
TM
must not exceed the maximum power level of the mixer
1
P
TM
– Mixer Conversion Loss
2
must be less than +5 dBm so as to not exceed the 1 dB
compression level for the IF input to the 85309B.
Note
If the calculated power level at the mixer is
insufficient to achieve the desired accuracy
from the reference channel, the transmit
power or the reference antenna gain must
be increased.
1.+26dBm(85320A/B,85320A/B-H50),
+20dBm(85320A/B-H20).
2. Refer to Table 10 in the
“
Antenna measurement
components catalog” section on page 52 for
mixer conversion loss.