This letter presents a 89–93-GHz interference-tolerant radar supporting simultaneous operations of multiple users over a 4-GHz bandwidth. Radar interferences resulted from concurrent transmissions of multiple users can be effectively eliminated by employing frequency hopping (FH) on each radar with a corresponding one-coincidence code. The superheterodyne architecture is adopted for the radar front ends to ensure the image rejection and LO leakage levels required by the FH agility. Implemented in 28-nm CMOS technology, the transmitter (TX) provides an output power of 7.1 dBm, and the receiver (RX) achieves a noise figure of 10 dB and −12 dBm 1-dB compression point over the entire band of interest. In addition, a cost-effective TX (RX) module with the CMOS TX (RX) chip and a Rogers patch antenna is developed for over-the-air verifications. The measured range resolution is 3.75 cm. Under a 0.9-V supply, the CMOS front ends consume 273 mW and occupy 2.75 mm2.