To increase a communication success rate with a radio slave unit even in an adverse communication environment is by having plural antennas and strengthening the directivity of radio waves in a specific direction by means of the interaction of the antennas.
Antennas 11a and 11b are connected to a modulation/ demodulation circuit 31, sends receiving radio waves from a radio slave unit to the circuit 31 and transmits transmission radio waves from the circuit 31 to the radio slave unit. The circuit 31 demodulates a received signal and modulates a telegraphic message from a control circuit 29. The control circuit 29 analyzes a received telegraphic message from the circuit 31 and sets the telegraphic message information of inputted data from an input-output circuit 27. The input-output circuit 27 performs input-output control of the received telegraphic message to a touch panel display liquid crystal keyboard part 25. In such a case, directivity is higher in the range where radio waves transmitted from the antennas 11a and 11b of portable radio equipment 3 than in the range where radio waves transmitted from portable radio equipment having one antenna. Then, a communication success rate becomes high even under adverse communication environment.
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OSAKA GAS CO LTD
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