Abstract: Antenna systems are provided including a chassi and first and second radiating elements coupled to the chassi. The first radiating element is configured to amplify excitation of the chassi and the second radiating element is configured to reduce excitation of the chassi so as to reduce mutual coupling in the antenna system. Related co-located antennas and methods of controlling mutual coupling are also provided.

Abstract: An antenna arrangement for a portable communication device, and portable communication device including such an antenna arrangement are described. The antenna arrangement includes antenna patches that are configured to be connected to respective feeding potentials and include a variable capacitance feeding. The antenna patches are separated by a gap and have lengths approximately equal to each other.

Abstract: According to exemplary embodiments of the present invention, non-uniform helical antennas are described for use in two or more frequency hyperbands. For example, non-uniform helical antennas can be designed according to the present invention for usage in portable terminals capable of operating both at 800 MHz and at 1900 MHz. Tuning to both resonance frequencies can be accomplished by varying parameters of the helical antennas including, for example, the pitch angle, coil diameter, length and number and spacing of the coil turns.

Abstract: According to exemplary embodiments of the present invention, retractable antennas are described for use in two or more frequency hyperbands. The retractable antennas can include a whip antenna, operable when the retractable antenna is extended and a non-uniform helical antenna, operable when the retractable antenna is retracted. For example, retractable antennas can be designed according to the present invention for usage in portable terminals capable of operating both at 800 MHz and at 1900 MHz. Tuning for the whip antenna is accomplished using a matching circuit. Tuning to both resonance frequencies for the non-uniform helical antenna can be accomplished by varying parameters of the helical structure including, for example, the pitch angle, coil diameter, length and number and spacing of the coil turns.