Pneumatic tire monitor

A system (150) for monitoring pneumatic tire conditions for one or more tire/wheel assemblies (105) mounted on a vehicle (152), preferably in combination with a tire pressurizing and regulating apparatus (183), comprises a transponder with a transmitting antenna mounted on the wheel (172) for transmitting a signal indicating tire condition, one or more receivers (166; 161a ... d) with receiving antennas (160a ... d) fixedly mounted on the vehicle, and circuitry for processing the received signals. Circuitry for each transponder (188) is on a printed circuit board (185) within a protective housing (180) coaxial to the hub (170) of the wheel or wheel carrier. Each transmitting antenna is selected from the group comprising a partial loop antenna (191), a helical antenna (193), a circular dipole antenna, and a small coupling coil adjacent to an endless hoop antenna. The partial loop antenna (191) is mounted in each housing affixed around a portion of the circumference of the printed circuit board, having an angular arc length, and comprises a serpentine portion (191b) for increasing the effective length of the partial loop antenna without also extending the angular arc length.