Low/high frequency shared leakage antenna, base station apparatus and close-range detection system using the antenna

A base station apparatus including a communication device and a low/high frequency shared leakage antenna,

• wherein the low/high frequency shared leakage antenna comprises:
• a high-frequency leakage coaxial cable having an inner conductor and an outer conductor;
• a termination circuit that terminates the inner conductor and the outer conductor in impedance at one end of the high-frequency leakage coaxial cable;
• and
• a loop structure of a conductor line that is arranged near the high-frequency leakage coaxial cable while being in parallel therewith to perform a communication of low-frequency signals using the communication device,
• wherein a communication of high-frequency signals higher in frequency than the low-frequency signals is performed using the communication device through the high-frequency leakage coaxial cable;
• and
• wherein the sensitivity of effective sensitivity areas for the low-frequency signals is reduced by the loop structure to allow electromagnetic waves of the low-frequency signals to locally exist around the loop structure.

A close-range detection system comprising:

• a base station apparatus having a communication device and a low/high frequency shared leakage antenna;
• a central control apparatus;
• and a wireless tag,
• wherein the communication device includes a low-frequency communication device which communicates low-frequency signals and a high-frequency communication device which communicates high-frequency signals higher than that of the low-frequency communication device;
• wherein the low/high frequency shared leakage antenna comprises:
• a high-frequency leakage coaxial cable having an inner conductor and an outer conductor;
• a termination circuit that terminates the inner conductor and the outer conductor in impedance at one end of the high-frequency leakage coaxial cable;
• and
• a loop structure that is formed of a conductor line arranged near the high-frequency leakage coaxial cable while being in parallel therewith;
• wherein a part of the loop structure is shared with either of the inner conductor and the outer conductor of the high-frequency leakage coaxial cable;
• wherein the low/high frequency shared leakage antenna has a three-conductor structure formed of the high-frequency leakage coaxial cable and the conductor line of the loop structure;
• wherein the wireless tag includes an antenna sensitive to the high-frequency signals and the low-frequency signals, a high-frequency receiver circuit, and a low-frequency receiver circuit;
• wherein the central control apparatus reduces the sensitivity of effective sensitivity areas for the low-frequency signals with the loop structure of the low/high frequency shared leakage antenna to allow electromagnetic waves of the low-frequency signals to locally exist around the low/high frequency shared leakage antenna;
• and
• wherein the position of the wireless tag near the low/high frequency shared leakage antenna is detected using the low-frequency signals of the communication device, and
• wherein information communications with the wireless tag are performed using the high-frequency signals.