Master antenna design, RF filters, and power amplifiers. From VHF to mmWave, learn the techniques for designing PCBs that meet demanding RF specifications.
| Band | Frequency | Applications | Recommended Material |
|---|---|---|---|
| VHF | 30-300 MHz | FM radio, TV broadcast | FR-4 |
| UHF | 300 MHz-3 GHz | Cellular, WiFi, GPS | FR-4/Rogers |
| S-Band | 2-4 GHz | WiFi, weather radar | Rogers RO4350 |
| C-Band | 4-8 GHz | Satellite, WLAN | Rogers RO4003 |
| X-Band | 8-12 GHz | Radar, sat-comm | Rogers/Taconic |
| Ku-Band | 12-18 GHz | Satellite TV, radar | Rogers 3003 |
| K-Band | 18-27 GHz | 5G, backhaul | RT/duroid |
| mmWave | 28-100 GHz | 5G, automotive radar | RT/duroid 5880 |
Use Smith chart or matching networks. Target VSWR < 1.5:1 for most applications. L-match, Pi-match, or transformer matching based on bandwidth needs.
S11 (return loss) < -10 dB typical. S21 measures insertion loss or gain. S-parameters are essential for RF simulation and characterization.
Single-point ground for audio, distributed ground for RF. Via fences for isolation. Guard traces and shield cans for sensitive circuits.
RF design requires precise impedance control, low-loss materials, and careful attention to parasitics. Every trace is a transmission line. Ground planes must be solid. Via inductance matters. Component placement affects performance. Return loss and VSWR become critical specifications. Electromagnetic coupling between traces is a major concern.
Microstrip is simpler and more common below 10 GHz. CPW (Coplanar Waveguide) excels above 10 GHz due to lower dispersion and easier component mounting. Use GCPW (grounded CPW) for best isolation. CPW is preferred for mmWave, transitions, and when you need tight ground definition near the signal.
Ground vias provide low-inductance return paths and prevent parallel-plate mode propagation. Space vias at λ/10 or less to suppress resonances. For mmWave (28+ GHz), this means via spacing under 1mm. Use via fences around RF traces for isolation. Multiple vias per ground pad reduce inductance.