Antenna module

An antenna module includes a grounding element, first and second radiating conductors, and a decoupling unit. The grounding element has first and second grounding ends. The first radiating conductor includes a first feed-in end that is adjacent spacedly to the first grounding end and that is configured to be fed with a first RF signal. The second radiating conductor includes a second feed-in end that is adjacent spacedly to the second grounding end and that is configured to be fed with a second RF signal. The decoupling unit is connected electrically between a portion of the first radiating conductor and a portion of the second radiating conductor that are proximate to each other, and is one of a decoupling capacitor and a decoupling inductor.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Application No. 102131999, filed on Sep. 5, 2013.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an antenna module, more particularly to an antenna having a relatively small size and high isolation.

2. Description of the Related Art

Multiple-antenna system (e.g., multiple-input and multiple-output systems, MIMO systems) is generally used to improve data rate and channel capacity. However, since mobile electronic devices are made increasingly smaller, distances between multiple antennas in the same mobile electronic device are getting shorter. When two antennas are close to each other and operate at the same resonant frequency band, coupling effect between the antennas will result in low isolation therebetween, which degrades performances of the antennas.

A conventional antenna module as disclosed in U.S. Pat. No. 8,085,202 for improving isolation between two antennas is to include, on a ground plane between the antennas, an isolation element in a form of a slot for providing isolation between the two antennas. Nevertheless, the isolation element having the slot configuration may increase the size of the conventional antenna module.

Another conventional antenna module as disclosed in U.S. Pat. No. D606,058 for improving isolation between two antennas is to include a thin metal strip that is connected electrically between the two antennas. However, to precisely adjust the thin metal strip, various considerations, parameters and factors need to be taken, thereby complicating the adjustment.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an antenna module that may alleviate the above drawbacks of the prior art.

Accordingly, an antenna module of the present invention includes a grounding element, a first radiating conductor, a second radiating conductor and a decoupling unit.

The grounding element includes a first grounding end and a second grounding end.

The first radiating conductor includes a first feed-in end that is adjacent to and spaced apart from the first grounding end of the grounding element and that is configured to be fed with a first radio frequency signal.

The second radiating conductor is adjacent to and spaced from the first radiating conductor. The second radiating conductor includes a second feed-in end that is adjacent to and spaced apart from the second grounding end of the grounding element and that is configured to be fed with a second radio frequency signal.

The decoupling unit is connected electrically between a portion of the first radiating conductor and a portion of the second radiating conductor that are proximate to each other. The decoupling unit is one of a decoupling capacitor and a decoupling inductor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, a first preferred embodiment of an antenna module100according to the present invention is shown to include a grounding element1, a first radiating conductor2, a second radiating conductor3and a decoupling unit4.

The grounding element1includes a first grounding end11and a second grounding end12.

The first radiating conductor2includes a first feed-in portion21, a first grounding portion22and a first radiating portion23.

The first feed-in portion21is spaced apart from the grounding element1, and includes a first feed-in end211and a first connecting end212opposite to the first feed-in end211. The first feed-in end211is adjacent to the first grounding end11of the grounding element1, and is configured to be fed with a first radio frequency signal.

The first grounding portion22is connected electrically between the grounding element1and the first connecting end212of the first feed-in portion21. The first grounding portion22includes a first grounding segment221and a second grounding segment222. The first grounding segment221is connected electrically to and extends from the first connecting end212of the first feed-in portion21in a −x direction toward the second radiating conductor3. The second grounding segment222is connected electrically to the first grounding segment221opposite to the first connecting end212of the first feed-in portion21. The second grounding segment222is substantially perpendicular to and extends from the first grounding segment221away from the first connecting end212in a −y direction to connect electrically with the grounding element1.

The first radiating portion23is connected electrically to and extends from the first connecting end212of the first feed-in portion21in an x direction away from the first grounding portion22.

The second radiating conductor3includes a second feed-in portion31, a second grounding portion32and a second radiating portion33.

The second feed-in portion31is spaced apart from the grounding element1, and includes a second feed-in end311and a second connecting end312opposite to the second feed-in end311. The second feed-in end311is adjacent to the second grounding end12of the grounding element1, and is configured to be fed with a second radio frequency signal.

The second grounding portion32is connected electrically between the grounding element1and the second connecting end312of the second feed-in portion31. The second grounding portion32includes a third grounding segment321and a fourth grounding segment322. The third grounding segment321is connected electrically to and extends from the second connecting end312of the second feed-in portion31toward the first radiating conductor2in the x direction. The fourth grounding segment322is connected electrically to the third grounding segment321opposite to the second connecting end312of the second feed-in portion31. The fourth grounding segment322is substantially perpendicular to and extends from the third grounding segment321away from the second connecting end312in the −y direction to connect electrically with the grounding element1. It is noted that the fourth grounding segment322of the second radiating conductor3is proximate to the second grounding segment222of the first radiating conductor2.

The second radiating portion33is connected electrically to and extends from the second connecting end312of the second feed-in portion31away from the second grounding portion32.

In addition, the first grounding end11and the second grounding end12of this preferred embodiment are connected electrically to two conductive shields of two respective coaxial cables (not shown) for receiving grounding signals, respectively. The first feed-in end211and the second feed-in end311of this preferred embodiment are connected electrically to center cores of the coaxial cables for receiving the first radio frequency signal and the second radio frequency signal, respectively. Moreover, the first radiating conductor2of this preferred embodiment cooperates with the grounding element1to form an inverted-F antenna, and the second radiating conductor3of this preferred embodiment cooperates with the grounding element1to form another inverted-F antenna.

The decoupling unit4is connected electrically between a portion of the first radiating conductor2and a portion of the second radiating conductor3that are proximate to each other. In this preferred embodiment, the decoupling unit4is a decoupling capacitor (C) connected electrically between the second grounding segment222of the first grounding portion22of the first radiating conductor2and the fourth grounding segment322of the second grounding portion32of the second radiating conductor3. The decoupling capacitor (C) may reduce an inductive coupling effect between the first and second radiating conductors2,3. In this preferred embodiment, the decoupling capacitor (C) is connected electrically between a portion of the second grounding segment222and a portion of the fourth grounding segment322that are away from the grounding element1. However, the decoupling capacitor (C) may be connected electrically to other portions of the second and fourth grounding segments222,322in other embodiments of the present invention.

FIG. 2is a plot showing S-parameters of the antenna module100of the first preferred embodiment according to the present invention. A curve line (S11) indicates a return loss related to the first feed-in end211of the first feed-in portion21of the first radiating conductor2. A curve line (S22) indicates a return loss related to the second feed-in end311of the second feed-in portion31of the second radiating conductor3. A curve line (S21) indicates isolation between the first feed-in end211of the first radiating conductor2and the second feed-in end311of the second radiating conductor3.

FIG. 3is a plot showing S-parameters of an antenna module that differs from the first preferred embodiment in that the decoupling unit4is omitted. Comparing the curve line (S21) ofFIG. 3with the curve line (S21) ofFIG. 2under the frequency of around 1.9 GHz, it is evident that the decoupling unit4may effectively improve the isolation between the first and second radiating conductors2,3.

FIG. 4is a radiation pattern of the first radiating conductor2operating with the grounding element1in the first preferred embodiment, andFIG. 5is a radiation pattern of the second radiating conductor3operating with the grounding element1in the first preferred embodiment. The radiation pattern shown inFIG. 4is substantially symmetrical with the radiation pattern shown inFIG. 5about the y direction, and, correlation between the radiation patterns of the first and second radiating conductors2,3is low. Therefore, the antenna module100of the first preferred embodiment is suitable to be applied to MIMO systems.

Referring toFIG. 6, a second preferred embodiment of the antenna module100according to the present invention is shown to be similar to the first preferred embodiment. The differences reside in the first radiating portion23, the second radiating portion33and the decoupling unit4.

In this preferred embodiment, the first radiating portion23includes a first connecting segment231, a first intermediate segment232and a first free segment233. The first connecting segment231includes a first end part234connected electrically to the first connecting end212of the first feed-in portion21, and extends from the first connecting end212of the first feed-in portion21in the x direction away from the second radiating conductor3. The first intermediate segment232is connected electrically to the first connecting segment231opposite to the first feed-in portion21, and extends in the y direction away from the grounding element1. The first free segment233is connected electrically to the first intermediate segment232opposite to the first connecting segment231, extends in the −x direction toward the second radiating conductor3, and includes a second end part235opposite to the first end part234.

The second radiating portion33includes a second connecting segment331, a second intermediate segment332and a second free segment333. The second connecting segment331includes a third free end part334connected electrically to the second connecting end312of the second feed-in portion31, and extends from the second connecting end312of the second feed-in portion31in the −x direction away from the first radiating conductor2. The second intermediate segment332is connected electrically to the second connecting segment331opposite to the second feed-in portion31, and extends in the y direction away from the grounding element1. The second free segment333is connected electrically to the second intermediate segment332opposite to the second connecting segment331, extends in the x direction toward the first radiating conductor2, and includes a fourth end part335opposite to the third end part334. The second end part235of the first radiating portion23is proximate to the fourth end part335of the second radiating portion33.

In this embodiment, the decoupling unit4is a decoupling inductor (L) that is connected electrically between the second end part235of the first radiating portion23and the fourth end part335of the second radiating portion33. The decoupling inductor (L) may reduce capacitive coupling effect between the first and second radiating conductors2,3.

FIG. 7is a plot showing S-parameters of the antenna module100of the second preferred embodiment according to the present invention.FIG. 8is a plot showing S-parameters of another antenna module that differs from the second preferred embodiment in that the decoupling unit4is omitted. Comparing the curve line (S21) ofFIG. 7with the curve line (S21) ofFIG. 8under the frequency of around 2.1 GHz, it is evident that the decoupling unit4may effectively improve the isolation between the first and second radiating conductors2,3.

FIG. 9is a radiation pattern of the first radiating conductor2operating with the grounding element1in the second preferred embodiment, andFIG. 10is a radiation pattern of the second radiating conductor3operating with the grounding element1in the second preferred embodiment. The radiation pattern shown inFIG. 9is substantially symmetrical with the radiation pattern shown inFIG. 10about the y axis, and, correlation between the radiation patterns of the first and second radiating conductors2,3is low. Therefore, the second preferred embodiment of the antenna module100is suitable to be applied to MIMO systems.

Referring toFIG. 11, a third preferred embodiment of the antenna module100according to the present invention is shown to be similar to the first preferred embodiment. The major differences reside in the following. In this preferred embodiment, the first grounding portion22of the first radiating conductor2and the second grounding portion32of the second radiating conductor3are omitted. In other words, the first radiating conductor2and the grounding element1cooperatively form a monopole antenna, and the second radiating conductor3and the grounding element1cooperatively form another monopole antenna. The first feed-in portion21is proximate to the second feed-in portion31in this preferred embodiment. The decoupling unit4is the decoupling capacitor (C) connected electrically between the first feed-in portion21and the second feed-in portion31. The decoupling capacitor (C) in this preferred embodiment is connected electrically between the first connecting end212of the first feed-in portion21and the second connecting end312of the second feed-in portion31. However, the decoupling capacitor (C) may be connected electrically to other portions of the first and second feed-in portions21,31in other embodiments of the present invention.

Referring toFIG. 12, a fourth preferred embodiment of the antenna module100according to the present invention is shown. In this preferred embodiment, the first grounding portion22of the first radiating conductor2and the second grounding portion32of the second radiating conductor3are omitted. In other words, the first radiating conductor2and the grounding element1cooperatively form a monopole antenna, and the second radiating conductor3and the grounding element1cooperatively form another monopole antenna. Moreover, the first radiating portion23is an elongated conductor extending from the first connecting end212of the first feed-in portion21in the −x direction toward the second radiating conductor3. The second radiating portion33is an elongated conductor extending from the second connecting end312of the second feed-in portion31in the x direction toward the first radiating conductor2. Similar to the second preferred embodiment, the second end part235of the first radiating portion23in this preferred embodiment is proximate to the fourth end part335of the second radiating portion33. The decoupling unit4is the decoupling inductor (L) connected electrically between the second end part235and the fourth end part335.

To conclude, according to the present invention, the decoupling unit4(i.e., the decoupling capacitor (C) or the decoupling inductor (L)) of the antenna module100are connected electrically between the positions of the first radiating conductor2and the second radiating conductor3that are proximate to each other, such that the inductive/capacitive coupling effect between the first radiating conductor2and the second radiating conductor3may be reduced. Therefore, the isolation between the first radiating conductor2and the second radiating conductor3under operation of the antenna module100may be improved, and signal transmission performance may be maintained. Further, the antenna module100may have a relatively small size.