Nokia 3155 Guide

Nokia Customer Care
3155/3155i (RM-41), 3152 (RM-61)
Mobile Terminal
ISSUE 1 07/2005 Company Confidential ©2005 Nokia Corporation
Antenna Description and
Troubleshooting

3155/3155i (RM-41), 3152 (RM-61)
Antenna Description and Troubleshooting
Page 2 ©2005 Nokia Corporation Company Confidential ISSUE 1 07/2005
Contents Page
Introduction ..................................................................................................................................................... 3
Whip Antenna ..............................................................................................................................................3
Failures and Corrective Measures.............................................................................................................. 4
Damaged Whips ........................................................................................................................................ 4
Antenna Position into D-cover ............................................................................................................. 5
Obstructed RF Feed Pad or Missing Matching Circuit ................................................................... 6
Broken or Missing Bottom Antenna Clip or Matching Circuit..................................................... 6
Obstructed Whip Stopper....................................................................................................................... 7
GPS Antenna .............................................................................................................................................. 8
UIM Card Holder ....................................................................................................................................... 8

Nokia Customer Care Antenna Description and Troubleshooting
3155/3155i (RM-41), 3152 (RM-61)
ISSUE 1 07/2005 ©2005 Nokia Corporation Company Confidential Page 3
Introduction
This troubleshooting guide addresses potential failures that affect antenna performance
of the 3155/3155i/3152, and discusses methods for correction of these failures.
Whip Antenna
Check the following minimum visual quality standards of the whip assembly:
• No physical cracks or mechanical defects.
• No excess oil, dirt, or particles appear on the parts.
• Whip cap and sheath over the mold parting line (flash or offset) is less
than 0.1 mm.
• NiTi extrusion must completely cover the NiTi wire. No uncovered NiTi wire can
be seen from the tube side.
• Proper printing is present (found on the plastic connector).
• Whip cap must be perpendicular to the NiTi wire (maximum of 5°).
• Antenna straw must not appear twisted, cracked, bent, or discolored.
• No gate flash greater than 0.1 mm anywhere on the assembly.
• Feed contact must appear at a 45-degree angle and must be free from damage,
deformation, or unusual bending.
• Straw must be approximately 5.0mm from the end of the split bottom stop.
Figure 1: Whip antenna assembly
The whip antenna is shipped fully retracted with the telescopic section fully collapsed.
The feed contact must appear at a 45-degree angle and must be free from damage,
deformation, or unusual bending. The straw must be approximately 5.0mm from the end
of the bottom stop.
Cap
Stubby tower
O-Ring
Connector
Straw
Bottom stopper
Telescopic tube

3155/3155i (RM-41), 3152 (RM-61)
Antenna Description and Troubleshooting
Page 4 ©2005 Nokia Corporation Company Confidential ISSUE 1 07/2005
Failures and Corrective Measures
Figure 2: Whip retracted and whip extended
Note in Figure 2 that when the whip is properly installed, the cap clicks into the antenna
tower when the whip is fully retracted. When fully extended, the length from the end of
antenna tower to the top of the cap must be around 118mm.
Damaged Whips
Figure 3 shows what the whip must look like when it is retracted and extended. If the
whip is damaged, replace it.
Figure 3: Whip stand-alone in retracted and extended positions

Nokia Customer Care Antenna Description and Troubleshooting
3155/3155i (RM-41), 3152 (RM-61)
ISSUE 1 07/2005 ©2005 Nokia Corporation Company Confidential Page 5
Antenna Position into D-cover
The internal antenna and whip are assembled into the D-cover as shown in Figure 4. If
no internal antenna is installed, the antenna gain will be degraded by more than 25 dB.
Figure 4: D-cover assembly
• If the whip antenna is missing, install one.
• If any part of the whip/stub antenna looks obviously damaged, then replace the
whip/stub antenna.
To take the whip/stub antenna out of the D-cover:
a. Insert tip of a small screw driver under snap.
b. Pry snap upward slightly (less than 1 mm). Bending snap too far upward will
damage it.
c. Apply slight pressure to antenna to remove it.
Figure 5: Uninstalling a whip/stub antenna from a D-cover
Whip/Stub antenna
a. Insert flat blade screw
driver
b. Pry snap upward less
than 1mm
c. Apply slight pressure
in direction of the arrow

3155/3155i (RM-41), 3152 (RM-61)
Antenna Description and Troubleshooting
Page 6 ©2005 Nokia Corporation Company Confidential ISSUE 1 07/2005
Obstructed RF Feed Pad or Missing Matching Circuit
If any portion of the upper clip is obstructed, removed, or covered, the antenna
connector will not make contact with the PWB and the antenna performance will
degrade. If the antenna connector does not touch clip, the antenna gain will degrade by
more than 25 dB.
Figure 6: PWB layout of the RF feed pad and the matching circuit
The matching circuit is right next to the upper clip. The matching circuit consists of a
shunt inductor of 12nH, a series cap of 2.2pF, and a series inductor of 3.9nH. If the
matching circuit is not installed properly or any of the components are missing, the
extended antenna gain will be degraded by about 25dB and the retracted antenna gain
will degrade by about 15dB.
• If corrosion is present or the pad is missing, replace the PWB and the mobile
terminal.
Broken or Missing Bottom Antenna Clip or Matching Circuit
If the bottom antenna clip does not contact the whip stopper when the whip is fully
retracted, the antenna gain will degrade by about 4-5dB at Cell band and 3-10dB at PCS
band when the whip is retracted.
The bottom matching circuit is right next to the bottom antenna clip and consists of a
series cap of 2.7pF. If the bottom matching circuit is not installed properly or the
component is missing, then the retracted antenna gain will degrade by about 15dB.
Matching circuit
Upper clip
Switch connector

Nokia Customer Care Antenna Description and Troubleshooting
3155/3155i (RM-41), 3152 (RM-61)
ISSUE 1 07/2005 ©2005 Nokia Corporation Company Confidential Page 7
Figure 7: Bottom antenna clip
• If the antenna clip is installed backwards, is damaged, or is missing, install a new
bottom antenna clip in the correct position.
Obstructed Whip Stopper
If the whip stopper does not properly contact the bottom antenna clip, then the
retracted antenna gain will degrade by about 4-5dB at Cell band and 3-10dB at PCS
band when the whip is retracted.
Figure 8: Whip stopper when the whip is fully retracted
• If the whip stopper is corroded or blocked by the whip straw, replace the whip
assembly.
• If the whip stopper is obstructed or dirty, remove the obstruction and/or dirt.
Bottom clipBottom matching circuit
Whip stopper contacts
the bottom antenna clip

3155/3155i (RM-41), 3152 (RM-61)
Antenna Description and Troubleshooting
Page 8 ©2005 Nokia Corporation Company Confidential ISSUE 1 07/2005
GPS Antenna
The GPS antenna is a ceramic chip soldered on the PWB. It has a matching circuit of
series 0R and a shunt inductor of 2.0nH.
Figure 9: Position of the GPS antenna on the PWB
• If the GPS antenna looks obviously damaged, replace it.
• If the GPS antenna is not present, install one (only for 3155i).
• If matching circuit is not properly installed or any of the two components are
missing, install the proper matching circuit.
UIM Card Holder
The card holder is grounded through grounding tabs. If the card holder is not properly
grounded, the CDMA antenna performance can be degraded. If the grounding tabs are
deformed or damaged, replace the card tray.
Figure 10: RUIM card holder assembled in D-cover
GPS antenna Matching circuit (opposite side of PWB)
Grounding Tabs
UIM Door