Technical Specs
Table Of Contents
- Important Notice
- Safety and Hazards
- Limitation of Liability
- Patents
- Copyright
- Trademarks
- Contact Information
- Revision History
- 1: Introduction
- 2: Electrical Specifications
- 3: RF Specifications
- 4: Power
- 5: Software Interface
- 6: Mechanical and Environmental Specifications
- 7: Regulatory Compliance and Industry Certifications
- A: Antenna Specification
- B: Design Checklist
- C: Packaging
- D: References
- E: Acronyms
- Index
RF Specifications
Rev 3 Oct.20 35 41113694
Antenna and Cabling
When selecting the antenna and cable, it is critical to RF performance to match antenna
gain and cable loss.
Note: For detailed electrical performance criteria, see Appendix A: Antenna Specification on
page 58.
Choosing the Correct Antenna and Cabling
When matching antennas and cabling:
• The antenna (and associated circuitry) should have a nominal impedance of 50
with a return loss of better than 10 dB across each frequency band of operation.
• The system gain value affects both radiated power and regulatory (FCC, IC, CE, etc.)
test results.
Designing Custom Antennas
Consider the following points when designing custom antennas:
• A skilled RF engineer should do the development to ensure that the RF performance
is maintained.
• If both UMTS and CDMA modules will be installed in the same platform, you may
want to develop separate antennas for maximum performance.
Determining the Antenna’s Location
When deciding where to put the antennas:
• Antenna location may affect RF performance. Although the module is shielded to
prevent interference in most applications, the placement of the antenna is still very
important—if the host device is insufficiently shielded, high levels of broadband or
spurious noise can degrade the module’s performance.
• Connecting cables between the module and the antenna must have 50 impedance.
If the impedance of the module is mismatched, RF performance is reduced signifi-
cantly.
• Antenna cables should be routed, if possible, away from noise sources (switching
power supplies, LCD assemblies, etc.). If the cables are near the noise sources, the
noise may be coupled into the RF cable and into the antenna. See Interference from
Other Wireless Devices on page 36.
Disabling the Diversity Antenna
Certification testing of a device with an integrated EM7411 may require the module’s main
and diversity antennas to be tested separately.
To facilitate this testing, receive diversity can be enabled/disabled using AT commands:
• !RXDEN—Used to enable/disable diversity for single-cell call (no carrier aggre-
gation).
• !LTERXCONTROL—Used to enable/disable paths (in carrier aggregation scenarios)
after a call is set up.