Abstract: A dipole antenna is provided. The dipole antenna includes a signal line, a ground line, a substrate, a first radiation element and a second radiation element. The substrate includes a first surface and a second surface, wherein the first surface is opposite to the second surface. The first radiation element is disposed on the first surface and electrically connected to the signal line, wherein the first radiation element comprises a first connection portion and a first extending portion, the first extending portion comprises a first bending portion, the first bending portion forms a first section and a second section on the first extending portion, and the first section is connected to the first connection portion. The second radiation element is disposed on the second surface and electrically connected to the ground line, wherein the second radiation element comprises a second connection portion.

Abstract: A communications device capable of simultaneously operating in a dual-band CDMA communications system having a cellular and a PCS CDMA communications systems and a dual-band GSM communications system having a GSM 900 and a GSM 1800 communications systems includes a radio signal transceiver module, a CDMA module, a GSM module, a first CDMA filtering unit, a second CDMA filtering unit, a first GSM filtering unit, and a second GSM filtering unit. The first CDMA filtering unit, the second CDMA filtering unit, the first GSM filtering unit, and the second GSM filtering unit are utilized for discarding signals in an overlapping frequency band between the dual-band CDMA and the dual-band GSM communications systems.

Abstract: A wireless signal transceiver device for receiving wireless signals of multiple frequency bands has an antenna, a radio frequency signal processing unit, an antenna switch module, a primary antenna matching circuit, and an auxiliary antenna matching module. The radio frequency signal processing unit outputs a control signal according to the frequency band of the wireless signal processed. The antenna switch module has a first signal terminal, and a plurality of second signal terminals coupled to the radio frequency signal processing unit, and switches a signal connection between the first signal terminal and one second signal terminal of the plurality of second signal terminals according to the control signal. The primary antenna matching circuit roughly matches the antenna, and the auxiliary antenna matching module matches the antenna with the primary antenna matching circuit based on the frequency band of the wireless signal processed by the radio frequency signal processing unit.

Abstract: A method for adjustment of a radio-frequency circuit by impedance loading features includes designing a plurality of test fixtures each corresponding to an impedance loading area according to a predefined operating frequency band, coupling each of the plurality of test fixtures to a test point of the radio-frequency circuit for measuring a plurality of radio-frequency characteristic sets, determining an optimal impedance loading area of the radio-frequency circuit according to the plurality of radio-frequency characteristic sets, and adjusting the radio-frequency circuit according to the optimal impedance loading area.

Abstract: A communications device capable of simultaneously operating in a dual-band CDMA communications system having a cellular and a PCS CDMA communications systems and a dual-band GSM communications system having a GSM 900 and a GSM 1800 communications systems includes a radio signal transceiver module, a CDMA module, a GSM module, a first CDMA filtering unit, a second CDMA filtering unit, a first GSM filtering unit, and a second GSM filtering unit. The first CDMA filtering unit, the second CDMA filtering unit, the first GSM filtering unit, and the second GSM filtering unit are utilized for discarding signals in an overlapping frequency band between the dual-band CDMA and the dual-band GSM communications systems.

Abstract: A communication device capable of operating in a first and a second communications systems includes a radio signal transceiver module, a first reception module for receiving signals from the first communications system, a first transmitting module for transmitting signals to the first communications system, a second reception module for receiving signals from the second communications system, a second transmitting module for transmitting signals to the second communications system, a first filtering unit coupled to the first transmitting module for filtering out signals in an overlapping frequency band between the first transmitting module and the second reception module, and a second filtering unit coupled to the second transmitting module for filtering out signals in an overlapping frequency band between the second transmitting module and the first reception module.

Abstract: A heterojunction bipolar transistor (HBT) power transistor with improved ruggedness is disclosed. The optimized design of HBT power transistor combines the use of ballasting resistors, coupling capacitors, as well as novel layout of the transistor cell, which avoids the problem of thermal runaway while maintaining the performance of the HBT power transistor.

Abstract: A novel design of high frequency hidden hand-held antenna which includes two metal arms above a lower arm of finite ground plane. By properly choosing the lengths of these arms and the separations between them, the bandwidth can be broadened more than 20%. Thus, it is suitable for personal mobile communication applications. A full wave equivalent circuit analytic model is also developed to analyze and optimize the geometrical configuration including the lengths and separations between the arms. Numerical analyses for current distribution on the conductor surface and various antenna characteristics such as input impedance and radiation patterns are computed by the use of the analytical models. Experimental results and numerical computations all confirm that better performance characteristics including broadened antenna bandwidth are achieved by this novel antenna.