Abstract: An antenna reflector, which can reflect incoming radio waves, is formed as a corner of a cube by orthogonally connecting three reflectors which can reflect incoming radio waves. The reflectors are formed from semiconductor layers, conductive sheets scattered on one surface of the semiconductor layers, insulator films formed on both sides of the semiconductor layers, conductor films provided on the opposite surface of each of the insulator films, and switching elements that are formed on the semiconductor layers and which connect the conductive sheets. As a result, if direct current voltage is applied between the resistor films, the reflectors reflect radio waves while radio waves are absorbed when no direct current voltage is applied, and thus, the reflected radio wave is modulated by the application and non-application of the direct current voltage.

Abstract: A communication system between a host station and a plurality of substations eliminates the possibility of a connection failure between the host and a given substation by attempting to establish a communication session a finite number of times. The host station transmits and receives data to and from the substations and processes the data. Every time one of the substations receives a pilot command from the host station, it selects a time slot provided in the host station's operation schedule based on digit information of the substation's unique ID code and transmits a response signal in that time slot to the host. If the response conflicts with another substation's response, information based on a different digit in the ID code is selected. Because the ID code is unique to the substation, a communication session will eventually be established, and the probability of a conflict with a response from another substation is reduced to zero by re-transmission by transmitting the request a finite number of times.

Abstract: The primary object of the invention is to realize a mobile object identification system of simple construction and low cost, in which the responding unit attached to a mobile object writes data only once when it receives write signals repeatedly in communication with antenna units. When a tag unit (responding unit) receives a write signal from a writing antenna unit, it writes data to the data memory when a completion flag is cleared. When the data is first written, a control circuit sets the completion flag. Then, if the tag unit receives additional write signals in the communication area of the same writing antenna unit, the control circuit invalidates the data write command on the ground that the completion flag is set, thereby preventing duplicate data writing.

Abstract: A method of fingerprint verification in which an input fingerprint is compared with a previously registered fingerprint, wherein the degree of correlation between a first section of the registered fingerprint and the input fingerprint is first determined by first-stage verification processing. If the correlation is higher than a first threshold value the input fingerprint is accepted, if lower than a second threshold value it is rejected, and if between these values, second-stage verification processing is executed in which a different section of the registered fingerprint is compared with the input fingerprint, and a final judgement made accordingly.