Integration Manual
Table Of Contents
- Preface
- Contents
- 1 System description
- 1.1 Overview
- 1.2 Architecture
- 1.3 Pin-out
- 1.4 Operating modes
- 1.5 Power management
- 1.6 System functions
- 1.7 RF connection
- 1.8 (U)SIM interface
- 1.9 Serial communication
- 1.10 DDC (I2C) interface
- 1.11 Audio Interface
- 1.12 General Purpose Input/Output (GPIO)
- 1.13 Reserved pins (RSVD)
- 1.14 Schematic for LISA-U series module integration
- 1.15 Approvals
- 2 Design-In
- 2.1 Design-in checklist
- 2.2 Design Guidelines for Layout
- 2.2.1 Layout guidelines per pin function
- 2.2.2 Footprint and paste mask
- 2.2.3 Placement
- 2.3 Thermal aspects
- 2.4 Antenna guidelines
- 2.5 ESD precautions
- 3 Features description
- 4 Handling and soldering
- 5 Product Testing
- Appendix
- A Migration to LISA-U2 series wireless modules
- B Glossary
- Related documents
- Revision history
- Contact
LISA-U series - System Integration Manual
3G.G2-HW-10002-A3 Preliminary Design-In
Page 123 of 160
Figure 66: |S
11
| and |S
21
| comparison between a 900 MHz tuned half wavelength dipole (green/purple) and a wideband
commercial antenna (yellow/cyan)
Instead if |S
21
| values for the tuned dipole are much better than the antenna under evaluation (like for marker 1/2
area of Figure 66, where dipole is 5 dB better), then it can be argued that the radiation of the target antenna
(the wideband dipole in this case) is considerably less.
The same procedure should be repeated on other bands with half wavelength dipole re-tuned to the band under
investigation.
For good antenna radiation performance, antenna dimensions should be comparable to a quarter of the
wavelength. Different antenna types can be used for the module, many of them (e.g. patch antennas,
monopole) are based on a resonating element that works in combination with a ground plane. The
ground plane, ideally infinite, can be reduced down to a minimum size that must be similar to one
quarter of the wavelength of the minimum frequency that has to be radiated (transmitted/received).
Numerical sample: frequency = 1 GHz wavelength = 30 cm minimum ground plane (or antenna
size) = 7.5 cm. Below this size, the antenna efficiency is reduced.
2.4.3 Antenna detection functionality
The internal antenna detect circuit is based on ADC measurement at ANT: the RF port is DC coupled to the ADC
unit in the baseband chip which injects a DC current (10 µA for 128 µs) on ANT and measures the resulting DC
voltage to evaluate the resistance from ANT pad to GND.
The antenna detection is forced by the +UANTR AT command: refer to the u-blox AT Commands Manual [3] for
more details on how to access this feature.
To achieve antenna detection functionality, use an RF antenna with built-in resistor from ANT signal to GND, or
implement an equivalent solution with a circuit between the antenna cable connection and the radiating
element as shown in Figure 67.