Wireless sensor networks use a variety of radio transceivers. (Some transcievers are integrated into a microcontrollers). In no particular order:
Nordic Semiconductor manufactures a variety of state of the art radio transceiver chips. Their miniature chips (i.e. 5x5 mm QFN packages) are specifically designed for short and medium range communication in small digital devices. The latest products include such features as automatic preamble and CRC generation, burst mode, sleep mode, ADC, and even embedded microcontroller (Nordic nRF24E2). Nordic transceivers are used in wireless mice and keyboards and several WSN designs.
Chipcon makes radio transceivers that are very popular in the WSN community. The company is focusing on the development of the ZigBee communication standard. Their chips have been used in many WSN designs such as Berkeley Motes. The has several products targeted specifically at WSN applications. For example, CC2431 includes a microcontroller with a radio that supports ZigBee/IEEE 802.15.4 standard. It also implements a unique on-chip feature called "location engine" to estimate relative location of sensor nodes with 0.5m resolution.
Freescale Semiconductor manufactures a variety several 802.15.4 SoC. The MC1322x series is highly integrated solution with radio and an ARM7 processor with typical peripherals and 96kB of RAM. Open source development system is available at The MC1322x Project.
Radiometrix manufactures relatively large radio transmitter, receiver and transceiver modules. They are convenient for prototype designs and appropriate in systems where extreme miniaturization is not necessary.
Jennic offers chips that combine microcontroller, IEEE802.15.4 ( 2.4GHz ) radio transceiver, and ADC. The chips support ZigBee, ZigBee Pro, and JenNet protocols, including meshed networks. Some Jennic chips include a "Time of Flight ranging engine".
- yet more low-power transceivers listed at "Low power radio + microcontroller recommendation?"