Layout considerations¶
Electrical and mechanical design files are available for download at the LumenRadio online support page.
MWA-N2 OEM module pad dimensions¶
Refer to the picture above. All units in mm.
- Oblong 1.4 x 2.79 (oblong edge a half circle with diameter 1.4)
- Small rectangles left edge 1.0 x 0.8 (red)
- Small squares right edge 1.02 x 1.02 (blue)
- Large square 2.0 x 2.0 (green)
Layout considerations for the main board¶
The MWA-N2 module has been specifically designed to achieve optimal RF performance. To maintain this, there are some important guidelines that is recommended to follow:
- The use of ground planes also on the carrier board for the MWA-N2 module cannot be emphasized enough. Good decoupling of any high-speed digital circuitry utilized on the carrier board is a must. Many embedded type microprocessors today have clock frequencies with clocks or overtones that reach well into the GHz range. It is possible for an embedded design to pass any EMC certification and still cause disturbances that will block the RF reception of the MWA-N2 module. The sensitivity of the MWA-N2 receiver is -94dBm therefore it is recommended to keep disturbances below -100dBm in the frequency range of operation. A near field probe connected to a spectrum analyzer will show if there are any disturbances present on the 2.45 GHz band generated by the microprocessor or any other device that is placed on the main board. Pay special attention to readymade LAN-products "Server in a RJ connector". They pass EMC certifications, but some of them radiate badly on 2.45 GHz. If disturbances can be seen on a spectrum analyzer - then the MWA-N2 module will have impaired reception.
- MWA-N2 OEM module has a supply voltage decoupling on the circuit board. The supply voltage still needs to be adequately filtered. If any disturbance or intermittent communication failures occur, as one of the troubleshooting steps; check the supply voltage for drop-outs, switch supply ripple etc.
- The top layer of the carrier board PCB under the MWA-N2 module should be free from copper, non isolated GND planes, traces or vias as indicated in drawing below. There is a ground plane on the MWA-N2 module bottom layer, but there are also supply lines. It is an unnecessary risk to rely on solder mask lacquer for isolation.
Note: The antenna keep out area above is necessary if you intend to use an internal chip antenna or if you plan to integrate the MWA-N3 radio module later.