Abstract: A multi-antenna system for differential wireless communication devices, such as transceivers, transmitters or receivers, includes a wireless communication device having a differential port including first and second nodes and a common ground for an antenna connection; a first antenna connected between the first node and the common ground; and a second antenna connected between the second node and the common ground.

Abstract: The operation of a mobile communication apparatus is enhanced particularly in the lower frequency portion of its bandwidth by connecting an electrically-conductive ground-enlarger to the electrically-conductive ground of the printed wired board (PWB) containing the communication circuitry such that the ground-enlarger effectively enlarges the ground of the PWB to load the antenna in the lower portion of its radio frequency band. The ground-enlarger may include stub ground-enlarger integrally formed on the PWB, or connected thereto, preferably at the end of the PWB opposite to that connected to the antenna. The antenna may be an internal antenna or an external antenna.

Abstract: A multi-band microwave antenna which is resonant and radiant at a high frequency band and at one or more lower frequency bands includes an electrically-conductive ground plane on one face of a dielectric substrate; an electrically conductive strip line on the opposite face of the dielectric substrate; a curved slot formed in the ground plane having a feed side electromagnetically coupled to the feed end of the strip line, and a load side electromagnetically coupled to the load end of the strip line, such that the slot is resonant and radiant at the high frequency band; and a further electrical conductor electrically connected to the ground plane to serve as a continuation thereof at the load side of the slot and electromagnetically coupled to the slot at the lower frequency bands such as to cause the slot to be resonant and radiant also at the lower frequency band or bands.