Assembly of chip antenna and circuit board

An assembly of a chip antenna and a circuit board includes a chip antenna and a circuit board. The circuit board includes a ground layer. The ground layer includes a hollow region formed adjacent to a periphery of the ground layer. The hollow region of the ground layer can be used for configuring an input impedance of the circuit board. The chip antenna is disposed in the hollow region of the ground layer, electrically connecting to the ground layer. The chip antenna includes input impedance. The input impedance of the chip antenna is adjustable to achieve a conjugate impedance match between the chip antenna and the circuit board such that the circuit board and the chip antenna can simultaneously radiate electromagnetic energy.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to an assembly of a chip antenna and a circuit board, and relates more particularly to an assembly of a chip antenna and a circuit board including a ground layer that can radiate electromagnetic energy with the chip antenna.

Due to the increasing need for high data column transmission, the technology for broadening of wireless networks is developing quickly. For example, the worldwide interoperability for microwave access (WiMax) technique supported strongly by international major companies such as Intel Corporation is rapidly emerging. According to the 802.16e standard, if the WiMax technique is applied, the wireless transmission frequency used between mobile devices such as notebooks and base stations can be in a range of from 2 to 6 GHZ, consequently capable of transmitting video and audio contents with better quality and instant messages.

In addition to the WiMax standard, the present invention can be embodied compliant with wireless standards such as GSM, DCS/PCS, GPS, BT, WiLan, WiFi, etc., and is not limited to the above-mentioned transmission bandwidths and methods of signal transmission.

During the rapid development of the communication industry, the performance of antennas has been a major key factor to the overall performance of wireless communication devices. However, as electronic devices are required to be compact, the antennas cannot perform as required within targeted frequency bands. Poor performance reflects the design difficulty of the antennas. Specifically, when the radiation metal surface area of a chip antenna is reduced, the electromagnetic wave emission efficiency of the antenna is decreased.

Thus, the issues relating to the reduced bandwidths and efficiencies of antennas due to miniaturization need to be resolved.

SUMMARY

The present invention provides an assembly of a chip antenna and a circuit board. The ground layer in the circuit board and the chip antenna are integrally configured to radiate electromagnetic energy. Changes in the ground layer layout in the circuit board can have corresponding effects on resistance and reactance. Signals can be sent from the chip antenna to the ground layer, then radiated from the ground layer. Thus, the ground layer can be used as an electromagnetic radiation metal layer, consequently increasing the electromagnetic radiation efficiency and bandwidth. As a result, it is possible to resolve the issues relating to the reduced bandwidths and efficiencies of antennas due to miniaturization.

One embodiment of the present invention comprises a chip antenna and a circuit board. The circuit board comprises a ground layer. The ground layer includes a hollow region formed adjacent to a periphery of the ground layer. The hollow region of the ground layer can be used for configuring an input impedance of the circuit board. The chip antenna is disposed in the hollow region of the ground layer, electrically connecting to the ground layer. The chip antenna creates input impedance. The input impedance of the chip antenna is adjustable to achieve a conjugate impedance match between the chip antenna and the circuit board such that the circuit board and the chip antenna can simultaneously radiate electromagnetic energy. In one embodiment of the present invention, the hollow region of the ground layer is located at the center of a long edge of the circuit board.

DETAILED DESCRIPTION

FIG. 1is a view showing an assembly of a chip antenna and a circuit board according to one embodiment of the present invention. An assembly10of a chip antenna and a circuit board comprises a chip antenna12and a circuit board11. The circuit board11comprises at least one dielectric layer111of, for example, FR4 fiber glass reinforced resin or ceramic and a ground layer112. The ground layer112comprises a hollow region1121formed adjacent to the periphery of the ground layer112. The chip antenna12is located in the hollow region1121of the ground layer112. A ground electrode of the chip antenna12connects to the ground layer112. The chip antenna12includes a signal electrode connecting to a micro-strip line115, which includes a feeding point configured for receiving an input signal.

Through the configuration of the hollow region1121of the chip antenna12, a desired input impedance of the circuit board11can be obtained. The adjustment of the input impedance of the circuit board11can allow the circuit board11and the chip antenna12to achieve a conjugate impedance match.

The chip antenna12includes a signal electrode (not shown). The signal electrode connects to a signal source (not shown). The chip antenna12further includes a ground electrode (not shown) connecting to the ground layer112. In the present embodiment, the circuit board11and the ground layer112have a length LBand a width WB. The hollow region1121has a length LNand a width WN. The location and dimension of the hollow region1121affect the impedance of the ground layer112. The adjustment of the input impedance of the chip antenna12can offset the reactance of the ground layer112, and can extend the effective radiation metal surface of the antenna. As a result, the ground layer112and the chip antenna12can simultaneously emit electromagnetic energy. In other words, the ground layer112can be deemed a metal layer having a large area for effectively radiating electromagnetic waves carrying signals from the signal source into the atmosphere. The hollow region1121can have a shape of rectangle, regular polygon, or can be irregular.

FIG. 2shows an assembly of a chip antenna and a circuit board according to another embodiment of the present invention. An assembly20of a chip antenna and a circuit board comprises a chip antenna12and a circuit board21. The circuit board21includes at least one dielectric layer211and a ground layer212including a hollow region2121formed adjacent to the periphery of the ground layer212. The chip antenna12is located in the hollow region2121of the ground layer212. The hollow region2121can be, as demonstrated in the present embodiment and the prior embodiment, located adjacent to the center position of an edge of the ground layer212. The hollow region2121can also be formed at a corner of the ground layer212, namely at a right angle corner. The chip antenna12includes a signal electrode connecting to a signal source (not shown) and a ground electrode (not shown) connecting to the ground layer212. The signal electrode of the chip antenna12connects to a micro-strip line215having a feeding point configured for receiving an input signal.

The location and dimension of the hollow region2121affect the impedance of the ground layer112. The adjustment of the input impedance of the chip antenna12can offset the reactance of the ground layer212, and can extend the effective radiation metal surface of the antenna. As a result, the ground layer212and the chip antenna12can simultaneously emit electromagnetic energy.

FIG. 3Ais a perspective view showing a circuit board having a length LTaccording to one embodiment of the present invention. Referring toFIG. 3A, the hollow region3121of the ground layer312is centrally positioned on the circuit board. The length LTof the circuit board may vary simultaneously with that of the ground layer312.FIG. 3Bis a graph showing the relationships between the length LTof a circuit board and resistance, and between the length LTof a circuit board and reactance according to one embodiment of the present invention. In such a graph, the resistances and the reactances corresponding to different lengths LTof a circuit board are shown. According to the requirements, a circuit board with a suitable length LTcan be selected. By balancing the reactance of the circuit board with the input resistance of the chip antenna, desired antenna characteristics can be acquired.

FIG. 4Ais a perspective view showing the hollow region of a ground layer located according to one embodiment of the present invention. As shown inFIG. 4A, the hollow region4121of a ground layer412can be moved along a long edge of the circuit board. Namely, the distance D between the hollow region4121and a short edge of the circuit board is variable. The hollow region4121has a fixed dimension.FIG. 4Bis a graph showing the relationships between the position of the hollow region of a ground layer and resistance, and between the position of the hollow region of a ground layer and reactance according to one embodiment of the present invention. InFIG. 4B, it can be seen that as the hollow region4121is moved closer to the center position of the long edge of the circuit board, the resistance become higher, resulting in better electromagnetic radiation efficiency. In fact, the arrangement of the hollow region4121is similar to that of traces of a circuit board. The hollow region4121is not easily arranged adjacent to the center of the long edge.