Beam forming antenna

#The present invention relates to a beam forming antenna and relates to a beam forming antenna that is configured using, e.g., a Butler matrix.

#In a device that transmits and receives electromagnetic waves using an antenna such as a wireless device and a radar device, an array antenna that orients beam directivity toward a desired direction using multiple antenna elements is commonly used. Because radio frequency signals, particularly, in a quasi-millimeter wave band or a millimeter wave band, experience a large propagation loss, it is commonly practiced to obtain a high antenna gain using an array antenna and, thereby, compensate for the propagation loss. However, a high antenna gain causes a beam that is radiated from an antenna to have sharp directivity. Therefore, in a case where a communication device is to communicate with correspondent nodes existing in a wide coverage or in a case where objects to be detected by a radar device exist in a wide area, a beam forming antenna is used that controls the phase and amplitude of a signal that is fed to an antenna element and changes a directivity direction of a beam according to situations.

#A beam forming antenna is described, e.g., in Patent Literature (PTL) 1. Furthermore, there is a beam forming antenna configured using a Butler matrix (e.g., PTL 2).

#FIG. 1 is a diagram depicting a configuration of a Butler matrix of an embodiment herein.

#FIG. 2 is a diagram depicting an example of a configuration of a beam forming antenna using phase shifters.

#FIG. 3 is a diagram depicting an example of a configuration of a beam forming antenna in a case where the antenna radiates beams in different multiple directions.

#Explanations are provided about beam forming antennas by technology (comparison examples) examined by the present inventors before the present application.

#Examples of circuitry for implementing beam forming antennas and their functionality are first described with FIGS. 2 to 4. FIG. 2 is a diagram depicting an example of a configuration of a beam forming antenna using phase shifters. FIG. 3 is a diagram depicting an example of a configuration of a beam forming antenna in a case where the antenna radiates beams in different multiple directions. FIG. 4 is a diagram depicting an example of a configuration of a beam forming antenna without using analog phase shifters.

#In the beam forming antenna in FIG. 2, a transmitting circuit 25 including individual variable phase shifters 22-1 to 22-N and variable gain elements 23-1 to 23-N is connected to electrical feeding paths to multiple antenna elements 21-1 to 21-N, and a signal into which beams radiated from the respective antenna elements are combined is controlled to be oriented toward a desired direction by appropriating setting the phases of the variable phase shifters 22-1 to 22-N and the amplitudes of the variable gain elements 23-1 to 23-N to desired values.