3.4 Antenna Placement and Routing
The antenna is the element used to convert the guided waves on the PCB traces to the free space
electromagnetic radiation. The placement and layout of the antenna are the keys to increased range and data
rates.
provides a summary of the recommended antennas to use with the CC3235MODx module.
Table 3-1. Antenna Guidelines
SR NO.
GUIDELINES
1
Place the antenna on an edge or corner of the PCB.
2
Ensure that no signals are routed across the antenna elements on all the layers of the PCB.
3
Most antennas, including the chip antenna used on the LaunchPad, require ground clearance on all the layers of the
PCB. Ensure that the ground is cleared on inner layers as well.
4
Ensure that there is provision to place matching components for the antenna. These must be tuned for best return loss
when the complete board is assembled. Any plastics or casing must also be mounted while tuning the antenna because
this can impact the impedance.
5
Ensure that the antenna impedance is 50 Ω because the module is rated to work only with a 50-Ω system.
6
In case of printed antenna, ensure that the simulation is performed with the solder mask in consideration.
7
Ensure that the antenna has a near omnidirectional pattern.
8
The feed point of the antenna is required to be grounded. This is only for the antenna type used on the CC3235MODx
LaunchPad. See the specific antenna data sheets for the recommendations.
3.5 Transmission Line Considerations
The RF signal from the module is routed to the antenna using a coplanar waveguide with ground (CPW-G)
structure. CPW-G structure offers the maximum amount of isolation and the best possible shielding to the
RF lines. In addition to the ground on the L1 layer, placing GND vias along the line also provides additional
shielding.
shows a cross section of the coplanar waveguide with the critical dimensions.
Figure 3-7. Coplanar Waveguide (Cross Section)
Layout Guidelines
38
CC3235MODSF SimpleLink™ Wi-Fi
®
and IoT Solution With MCU
LaunchPad™ Hardware
SWRU548C – FEBRUARY 2019 – REVISED SEPTEMBER 2021
Copyright © 2021 Texas Instruments Incorporated
Summary of Contents for CC3235MODASF
Page 2: ......
