How do I select a T/R module for a phased array radar application?
T/R Module Selection
Module integration levels: discrete T/R module (separate PA, LNA, phase shifter assembled on a module substrate, 10-50 cm²), multi-chip module (multiple bare dies on a common substrate, 1-5 cm²), and fully integrated RFIC T/R chip (all functions on one die, < 1 cm²). Higher integration reduces size and cost per element but limits flexibility and power handling. For large-format AESA radars: hundreds to thousands of modules, so cost per module is critical. Modern GaN MMIC-based modules cost $100-$500 each in volume.
| Parameter | Pulsed | CW/FMCW | Phased Array |
|---|---|---|---|
| Range Resolution | c/(2B) | c/(2B) | c/(2B) |
| Velocity Resolution | PRF dependent | Direct from Doppler | Coherent processing |
| Peak Power | High (kW-MW) | Low (mW-W) | Moderate per element |
| Complexity | Moderate | Low | High |
| Typical Application | Surveillance, weather | Altimeter, automotive | Tracking, multifunction |
- Performance verification: confirm specifications against the application requirements before finalizing the design
- Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
- Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades
- Interface compatibility: verify impedance, connector type, and mechanical form factor match the system architecture
Frequently Asked Questions
How do I specify the phase shifter?
6-bit phase shifter (64 states, 5.625° LSB): adequate for most phased arrays (supports sidelobes < -35 dB with calibration). 7-bit (128 states): needed for ultra-low sidelobe arrays (< -40 dB). Phase accuracy (RMS error after calibration): < 2° for communications, < 1° for precision tracking. Digital phase shifters (switched-line or switched-filter type) dominate in T/R modules.
What duty cycle can the module handle?
Duty cycle is limited by the PA's thermal and power supply design. GaN T/R modules: 10-30% duty cycle is typical for pulsed radar. CW operation: the module must handle the full average power continuously, requiring derating of the peak power. For 5G communications T/R modules: 100% duty cycle at reduced per-element power.