US Patent 7804458 Slot antenna

A communications device for sending and receiving an information signal. The communications device comprising an element having an opening defined therein for receiving an antenna, the element comprising first conductive material disposed proximate the opening and comprising transmitting and receiving circuits. The antenna comprises: a dielectric tubular member, second conductive material forming an exterior surface of the tubular member with the second conductive material defining a slot therein, a slot length approximately equal to one-half of a guided wavelength and a feed connected to the transmitting and receiving circuits and disposed proximate the slot for establishing currents in the second conductive material.