User Manual

Transmit & Receive Antenna VSWR – continued
G-2 1X SC4812T–MC BTS Optimization/ATP 5/21/04
DRAFT
Table G-1: VSWR Measurement Procedure – HP Test Set
Step Action HP TEST SET
1 For manual VSWR testing, using external directional coupler, refer to Figure G-1.
– Connect the communications test set RF IN/OUT port to the INPUT port of the directional
coupler.
– Connect the ANT IN port of the communication test set to the reverse (RVS) port on the
directional coupler. Terminate the forward port with a 50 ohm load.
– Install the antenna feed line to the output port on the directional coupler.
NOTE
Manual Communications Analyzer test setup (fields not indicated remain at default):
S Set screen to RF GEN.
– Set the RF Gen Freq to center frequency of actual CDMA carrier between 869–894 MHz for
TX and 824–849 MHz for RX.
– Set Amplitude to –30 dBm.
– Set Output Port to RF OUT.
– Set AFGen1 & AFGen2 to OFF.
2 Remove the antenna feed line and install an “RF short” onto the directional coupler output port.
NOTE
Set–up communication test set as follows (fields not indicated remain at default):
S Set screen to SPEC ANL.
– Under Controls, set input port to ANT.
–
Set Ref Level to –40 dBm.
– Under Controls, select Main, select Auxiliary.
– Under Controls, select AV G . Set Avg = 20.
3 – Record the reference level on the communications analyzer and Note as P
S
for reference.
– Replace the short with the antenna feedline. Record the reference level on the communications
analyzer and Note for as P
A
reference.
– Record the difference of the two readings in dB.
4 Calculate the VSWR per the equation shown to the right.
Where:
R
L(
dB) = P
A
(dBm) – P
S
(dBm)
P
A = Power reflected from antenna
P
S = Power reflected from short
A calculated value of –13.98 dB equates to VSWR of better than 1.5:1.
VSWR +
ȧ
ȧ
ȡ
Ȣ
1 ) 10
RL
20
1 – 10
RL
20
ȧ
ȧ
ȣ
Ȥ
5 If the readings indicate a potential problem, verify the physical integrity of all cables (including any
in–line components, pads, etc.) and associated connections up to the antenna. If problem still persists,
consult antenna OEM documentation for additional performance verification tests or replacement
information.
. . . continued on next page
G