Tri-band Operation Research Articles

Design and Test of a Mobile Antenna System With Tri-Band Operation for Broadband Satellite Communications and DBS Reception

The tri-band mobile antenna system for broadband multimedia services in the Ka/K-band and a simultaneous direct broadcast service in the Ku-band has been developed. The radiating part of the antenna consists of a shaped dual reflector system and a tri-band feed of circular polarization. The low-profile offset main reflector has an aperture size of 60 cm 20 cm; therefore, a fan beam is formed which is sharp in azimuth and wide in elevation. The feed system contains a protruding dielectric rod for Ka/K-band and 2 2 active phased array. The latter provides the beam for Ku-band along with four fast electrical beams for stable satellite tracking. The new tracking algorithm based on a fusion technique involving various sensors and fast electrical beams has also been introduced. The antenna system was mounted on a large ship and a test car, and successfully operated via Koreasat-3.

Dual-resonance monopole antenna with tuning stubs

A dual-resonance monopole antenna is proposed for application in mobile communications devices. The antenna is small in comparison with conventional monopole antennas as only one resonator is used to realise dual-resonance operation. The frequency ratio of the dual resonance is adjusted by employing a number of tuning stubs. It is demonstrated that GSM (Global System for Mobile Communications) tri-band operation including GSM900 (880–960 MHz), GSM1800 (1710–1880 MHz) and GSM1900 (1850–1990 MHz) can be achieved by using the monopole antenna with an overall size of 20×20×1 mm3 for a conventional handset.

A novel design methodology for reconfigurable frequency selective surfaces using genetic algorithms

In this paper, a new reconfigurable frequency selective surface (RFSS) design concept is introduced. A grid of simple metallic patches interconnected by a matrix of switches is proposed as the unit cell of an RFSS. The switches are independently addressable and provide significant transmission and reflection flexibility over a large range of frequencies. This flexibility is exploited by optimizing the switch settings using a genetic algorithm to produce a desired frequency response. The versatility of the design technique is demonstrated by presenting several examples of genetically optimized RFSS. The first example to be considered is a linearly polarized FSS that can be reconfigured for either single-, dual-, or tri-band operation. An RFSS design is also introduced that can be optimized to have a frequency response that is polarization independent in one state (i.e., for one combination of switch settings) and polarization dependent in another state.