Abstract: A tire inflation pressure sensing apparatus includes a transmitter provided on a wheel of a vehicle and a receiver provided on a body of the vehicle. The transmitter includes a pressure sensor working to generate a pressure signal and a charging unit configured to be charged with electrical power via a radio wave from the receiver. The transmitter is configured to be triggered to send out the pressure signal by a change of operation of the receiver from an ON-mode, in which the receiver sends out the radio wave, to an OFF-mode in which that stops sending out the radio wave. The receiver works to change the operation thereof alternately between the ON-mode and OFF-mode in accordance with predefined processes, so that reliable transmissions of both the radio wave and the pressure signal between the transmitter and receiver are ensured without determining the relative position of the transmitter and receiver.

Abstract: An antenna holder for holding an antenna includes signal wiring and ground wiring being disposed on a single circuit board as either one of an external element and an internal element respectively with one end electrically coupled with a circuit on the single circuit board for serving as the external element in a spiral shape and the internal element inside of the external element at a predetermined distance. The antenna holder is provided with a spacer for keeping the predetermined distance between the external and the internal elements as well as an external tilt suppressor for suppressing a tilt of the external element from a direction being orthogonal to the circuit board.

Abstract: An antenna includes outer and inner elements, one of which is a signal line and the other of which is a ground line. Each of the outer and inner elements is a helical element having helical portions. The inner element is arranged inside the outer element such that the outer and inner elements are spaced from each other. An axis of the outer element is parallel to that of the inner element.

Abstract: A vehicular antenna is mounted on a circuit board in a monitor. The circuit board has a conductor substrate that is used as a ground for the antenna, and it has a frame shape that has a rectangular inner edge. The circuit board has an electrical contact for connecting the antenna. The electrical contact is placed at ?/4 away from an axisymmetrical line (center line) with respect to the inner edge. As a result, a gain of the vehicular antenna is not reduced in a front direction even when the vehicular antenna uses the frame shape conductor as the ground.

Abstract: A tire inflation pressure sensing apparatus includes a transmitter provided on a wheel of a vehicle and a receiver provided on a body of the vehicle. The transmitter includes a pressure sensor working to generate a pressure signal and a charging unit configured to be charged with electrical power via a radio wave from the receiver. The transmitter is configured to be triggered to send out the pressure signal by a change of operation of the receiver from an ON-mode, in which the receiver sends out the radio wave, to an OFF-mode in which that stops sending out the radio wave. The receiver works to change the operation thereof alternately between the ON-mode and OFF-mode in accordance with predefined processes, so that reliable transmissions of both the radio wave and the pressure signal between the transmitter and receiver are ensured without determining the relative position of the transmitter and receiver.

Abstract: A vehicular antenna is mounted on a circuit board in a monitor. The circuit board has a conductor substrate that is used as a ground for the antenna, and it has a frame shape that has a rectangular inner edge. The circuit board has an electrical contact for connecting the antenna. The electrical contact is placed at &lgr;/4 away from an axisymmetrical line (center line) with respect to the inner edge. As a result, a gain of the vehicular antenna is not reduced in a front direction even when the vehicular antenna uses the frame shape conductor as the ground.