The radio frequency printed circuit boards, also called RF PCBs, pose a number of design challenges. These challenges arise from the highly intrusive nature of radio frequencies that can lead to noise induction as well as pickup. A number of steps can be taken to minimize this pickup and consequent deterioration of the PCB performance.
Ground Plane
Make sure that your PCB has as large a ground plane as possible. Ground planes help minimize not only ground loop currents but also RF leakage into circuit elements. An exception to this is the RF module itself. There should not be a ground plane underneath this module in order to allow proper RF propagation. If you have ground planes on both sides of the PCB, make plenty of vias to connect the two planes together at different points on the board.
Bypass Capacitors
All power supply outputs and power inputs for active electronic components must be bypassed with high quality capacitors, such as polarized Tantalum. The traces on an RF PCB are subject to RF pickup causing the current flowing through them to fluctuate. This may severely deteriorate the performance of the components these traces are connected to. Therefore, all power inputs to the components must be properly bypassed with capacitors.
Traces of Transmitter and Receiver Modules
Keep all the traces coming out of or going into the transmitter and receiver modules as small as possible. These traces act as antennas and may cause RF interference in circuit operation through introduction of RF noise.
Connectors and Cables
Always use coaxial cables and proper coax connectors for signals coming in or going out of RF PCBs. The coaxial cables and connectors have proper shielding to minimize RF pickup and transmission. An unshielded cable will act as an antenna and will severely deteriorate the circuit performance.
