Abstract: This antenna unit is adapted to be connected to an electronic device for transmitting a received radio signal to the electronic device. The antenna unit comprises a noise canceller for canceling noise generated in the electronic device and transmitted to the antenna unit through a ground line. The noise canceller is a conductive stub piece one end of which is electrically connected to an electromagnetic shield of the antenna unit and the other end of which is a free end. The stub piece has a length of about ¼ of a wavelength of the radio signal.

Abstract: This antenna unit is adapted to be connected to an electronic device for transmitting a received radio signal to the electronic device. The antenna unit comprises a noise canceller for canceling noise generated in the electronic device and transmitted to the antenna unit through a ground line. The noise canceller is a conductive stub piece one end of which is electrically connected to an electromagnetic shield of the antenna unit and the other end of which is a free end. The stub piece has a length of about ¼ of a wavelength of the radio signal.

Abstract: A wireless transmission-reception control system in which the data transmitted as a radio wave from more than one wireless transmitter along with an ID code are received by a wireless receiver and decoded at a front end decoder. The ID code of the transmitted data thus received is compared by a comparer with the ID code of the transmitted data already registered at a data register to discriminate if a collation of the data is to be made [or not], and only the transmitted data, the registration of which is confirmed, are decoded to have an output generated. The wireless transmitters each have different, fixed ID codes, and the wireless receiver may be switched over at least between a mode of registering an ID code and a mode of generating an output after the decoding of the transmitted data.