Abstract: A performance evaluation system for a multiple-input multiple-output (MIMO) antenna system receives simulation parameters from an input device, and simulates a MIMO antenna system accordingly. A method, also provided, further evaluates performance of the simulated MIMO antenna system when a series of radio frequency (RF) signals are transmitted through the MIMO antenna system, and displays a performance analysis result of the MIMO antenna system on a display device for evaluation of the performance of the simulated MIMO antenna system.

Abstract: A printed circuit board includes a first layer, a second layer, a number of vias each passing through the first and second layers, and a number of transmission lines. Each transmission line is connected between bonding pads of the two of the number of vias to form a helical-shaped transmission path by the vias and the transmission lines. As a result, the printed circuit board can generate inductive effect.

Abstract: A signal transmission apparatus includes two circuit layers. First and second ground sheets each has a rectangular area are arranged in the two circuit layers respectively. A third ground sheet is arranged between the two circuit layers. A differential pair includes a transmission line arranged between the first and third ground sheets and a transmission line arranged between the second and third ground sheets. The first to third ground sheets have same electric potential. Projections of the two rectangular areas on a surface where the third ground sheet in only have one common border with the third ground sheet. The third ground sheet is formed by extending the common border along a signal transmission direction. The differential pair includes a number of section pairs each composed of two sections arranged in the two transmission lines symmetrically. Every two adjacent section pairs are equivalent to a capacitor and an inductor.

Abstract: A signal transmission apparatus includes two circuit layers. First and second ground sheets are arranged in the two circuit layers respectively. A third ground sheet is arranged between the two circuit layers. A differential pair includes a transmission line arranged between the first and third ground sheets and a transmission line arranged between the second and third ground sheets. The first to third ground sheets have same electric potential. Projections of the first and second ground sheets on the third ground sheet superpose a border of the third ground sheet. The third ground sheet is formed by extending the border along a signal transmission direction.

Abstract: An electronic device includes a multi-frequency antenna. The multi-frequency antenna includes a ground portion, a support body, a radiation portion, and a strap. The ground portion defines a gap, and two grooves communicating with the gap and located at opposite ends of the gap. The radiation portion resists against a sidewall bounding the gap, and is connected to the strap. The radiation portion is accommodated in the gap and substantially coplanar with the ground portion. The radiation portion defines a slot. The support body is located in the gap and on the radiation portion, to support the strap.

Abstract: A high-frequency module includes an antenna, an impedance matching circuit, and a transmission wire. The transmission wire is connected between the antenna and the impedance matching circuit. The transmission wire includes a dielectric layer, a signal layer, and two ground layers. The signal layer and the ground layers are located on the dielectric layer. The ground layers are located at opposite sides of the signal layer respectively. A space is formed between a signal and each ground layer.

Abstract: A printed circuit board (PCB) includes a power layer, a ground layer, a through hole, and a conductor. The through hole goes through the power layer and the ground layer. The conductor includes a hollow columnar main body and an extending portion. The main body is formed in a bounding wall of the through hole, and is conductively connected to one of the power layer and the ground layer, and insulated from the other one of the power layer and the ground layer by an insulation area. The extending portion extends out from the circumferential surface of the main body. The extending portion extends into the insulation area and is insulated from the other one of the power layer and the ground layer, to increase an area of the power layer facing the ground layer.

Abstract: A compensation method compensates for a length offset between a first transmission line and a second transmission line of a differential signal transmission. The compensation method includes calculating a transmission speed of a first signal in the first transmission line, measuring lengths of the first and second transmission lines, calculating a transmission time of the first signal in the first transmission line, and calculating a relationship between permittivity values of the first and second transmission lines. The compensation method further changes the permittivity values of the first and second transmission lines according to the relationship.

Abstract: A printed circuit board includes first and second connector pads, first and second connection components, and first, second, and third transmission lines. A method for supporting two connectors on the printed circuit board is also provided. The printed circuit board is capable of supporting different types of connectors by setting the first and second connection components on the printed circuit board.