TECHNICAL FIELD

The invention relates to a planar complementary antenna and an antenna array formed with multiple such planar complementary antennas.

BACKGROUND

In the telecommunication industry, existing cellular antenna design tends to use a simple antenna, such as dipole antenna and invert-F antenna. However, these antennas have narrow bandwidth and low gain. With the emergence of 5G and other future wireless communication technologies, there is a need to provide antennas and hence communication devices that can provide improved performance.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention, there is provided a planar complementary antenna having a substrate; a planar dipole antenna arranged on the substrate; a loop antenna arranged on the substrate and operably connected with the planar dipole antenna; and a feed network for connection with a feed source. The feed network is operably connected with the planar dipole antenna and the loop antenna for feeding an electrical signal from the feed source to the planar dipole antenna and the loop antenna so as to form an electric dipole at the planar dipole antenna and a magnetic dipole at the loop antenna. The planar dipole antenna, the loop antenna and/or the feed network may be formed by conductive strips (e.g., Copper strips). The loop antenna need not be in the form of a closed loop, but can be a loop-like antenna with opposite ends close to each other but spaced apart. The loop antenna is preferably a single-loop antenna. The planar complementary antenna may be formed from a PCB substrate.

In one embodiment of the first aspect, the planar dipole antenna and the loop antenna are both arranged on a first side of the substrate. Alternatively, the planar dipole antenna and the loop antenna are arranged on opposite sides of the substrate.

In one embodiment of the first aspect, the planar dipole antenna and the loop antenna are directly connected with each other or they are formed integrally.

In one embodiment of the first aspect, the planar dipole antenna has a first antenna portion and a second antenna portion that are symmetric about at least one symmetric axis.

In one embodiment of the first aspect, the first and second antenna portions each include: a first conductive strip portion and a second conductive strip portion generally extending at an angle to the first conductive strip portion. The first conductive strip portion is generally elongated but need not be straight. Likewise, the second conductive strip portion is generally elongated but need not be straight. Preferably, the angle is about 90 degrees. Alternatively, the angle may be between 45 degrees and 135 degrees.

In one embodiment of the first aspect, the feed network is arranged on a second side of the substrate, and the second side is opposite the first side.

In one embodiment of the first aspect, the planar complementary antenna further includes one or more vias extending through the substrate; the feed network is operably connected with the planar dipole and the loop antenna through the one or more vias.

In one embodiment of the first aspect, the feed network comprises a balun network.

In one embodiment of the first aspect, the balun network comprises a first conductive strip and a second conductive strip.

In one embodiment of the first aspect, the first conductive strip provides an input portion for connection with the feed source.

In one embodiment of the first aspect, the second conductive strip provides a phase inverter.

In one embodiment of the first aspect, the first conductive strip and the second conductive strip are arranged on a second side of the substrate, wherein the second side is opposite the first side.

In one embodiment of the first aspect, the first conductive strip and the second conductive strip are spaced apart and extending substantially in parallel.

In one embodiment of the first aspect, the first conductive strip is arranged on a second side of the substrate and the second conductive strip is arranged on the first side of the substrate; wherein the second side is opposite the first side.

In one embodiment of the first aspect, the second conductive strip is connected directly across the loop antenna.

In one embodiment of the first aspect, the feed network comprises a differential feed network.

In one embodiment of the first aspect, the differential feed network is arranged on a second side of the substrate, wherein the second side is opposite the first side.

In one embodiment of the first aspect, the differential feed network comprises two input portions each arranged to receive a respective input signal, the two input signals being out of phase.

In one embodiment of the first aspect, the planar complementary antenna further includes a ground plane arranged on the first side of the substrate.

In one embodiment of the first aspect, the ground plane is at least partly integral with the loop antenna.

In one embodiment of the first aspect, the ground plane is spaced apart from the loop antenna.

In one embodiment of the first aspect, the planar complementary antenna is arranged for operation at GHz and THz frequencies.

In accordance with a second aspect of the invention, there is provided an antenna array having a substrate and a plurality of antenna units. Each of the antenna units includes a planar dipole antenna arranged on the substrate; a loop antenna arranged on the substrate and operably connected with the planar dipole antenna; and a feed network for connection with a feed source. The feed network is operably connected with the planar dipole antenna and the loop antenna for feeding an electrical signal from the feed source to the planar dipole antenna and the loop antenna so as to form an electric dipole at the planar dipole antenna and a magnetic dipole at the loop antenna. The planar dipole antenna, the loop antenna and/or the feed network may be formed by conductive strips (e.g., Copper strips). The loop antenna need not be in the form of a closed loop, but can be a loop-like antenna with opposite ends close to each other but spaced apart. The loop antenna is preferably a single-loop antenna. The antenna array may be formed from a PCB substrate.

In one embodiment of the second aspect, each of the antenna units includes a planar complementary antenna of the first aspect.

In one embodiment of the second aspect, the antenna array is arranged for operation at GHz and THz frequencies.

In accordance with a third aspect of the invention, there is provided a communication device including the planar complementary antenna of the first aspect. The communication device may be a mobile communication device.

In accordance with a fourth aspect of the invention, there is provided communication device the antenna array of the second aspect. The communication device may be a mobile communication device.

