Abstract: A signal branching filter according to the invention is a signal branching filter connected to a network having at least four terminals. The signal branching filter includes a first line one end of which is connected to a first terminal of the network, a second line one end of which is connected to a second terminal of the network, a third line one end of which is connected to a third terminal of network, and a fourth line one end of which is connected to a fourth terminal of the network. The other end of the first line and the other end of the second line are connected to each other at a first node, and the other end of the third line and the other end of the fourth line are connected to each other at a second node. When a signal is received from the first node, a phase difference between a phase of a signal appearing on a second node side of the third line and a phase of a signal appearing on a second node side of the fourth line is almost 180°±360°*n is an integer equal to or larger than 0).

Abstract: An amplifying circuit with a bypassing function includes an input terminal to which a signal is input from an antenna, an amplifier connected to the input terminal, a first inductor connected between the input port and a ground, and a bypass circuit connected between the input terminal and the output port of the amplifier. The bypass circuit includes a first port connected to the input terminal, a second port connected to the output port of the amplifier, a switch, a capacitor, and a second inductor. The switch is connected in series between the first and second ports. The capacitor is connected in series to the switch between the first and second ports. The second inductor is connected in series to the switch and the capacitor between the first and second ports. Signal power is not reduced drastically even when the signal passes through the bypass circuit.

Abstract: A signal branching filter according to the invention is a signal branching filter connected to a network having at least four terminals. The signal branching filter includes a first line one end of which is connected to a first terminal of the network, a second line one end of which is connected to a second terminal of the network, a third line one end of which is connected to a third terminal of network, and a fourth line one end of which is connected to a fourth terminal of the network. The other end of the first line and the other end of the second line are connected to each other at a first node, and the other end of the third line and the other end of the fourth line are connected to each other at a second node. When a signal is received from the first node, a phase difference between a phase of a signal appearing on a second node side of the third line and a phase of a signal appearing on a second node side of the fourth line is almost 180°±360°*n is an integer equal to or larger than 0).

Abstract: Provided is a composite antenna adapted for reduction in size while ensuring sufficient electrical isolation between antenna elements. The composite antenna comprises ground plane, first feeding point connected to ground plane, first conductor connected to first feeding point and disposed linearly symmetrically with respect to axis, second conductor connected to first conductor and disposed linearly symmetrically with respect to axis, second feeding point disposed in a position along axis, third conductor connecting second feeding point and second conductor, and fourth conductor connecting second feeding point and second conductor and disposed in a linearly symmetrical manner to third conductor with respect to axis.

Abstract: An amplifying circuit with a bypassing function includes an input terminal to which a signal is input from an antenna, an amplifier connected to the input terminal, a first inductor connected between the input port and a ground, and a bypass circuit connected between the input terminal and the output port of the amplifier. The bypass circuit includes a first port connected to the input terminal, a second port connected to the output port of the amplifier, a switch, a capacitor, and a second inductor. The switch is connected in series between the first and second ports. The capacitor is connected in series to the switch between the first and second ports. The second inductor is connected in series to the switch and the capacitor between the first and second ports.

Abstract: The antenna device comprises a ground substrate serving as ground, a feeder portion formed on the ground substrate, a first conductor connected to the feeder portion, and a second conductor being substantially equal to the first conductor in conductor length, which is connected to the ground substrate and disposed substantially parallel to the first conductor with a space therebetween. And, the first conductor and the second conductor are electrically connected to each other between each tip and a portion substantially at least ? in conductor length of each conductor from each tip.

Abstract: Provided is a composite antenna adapted for reduction in size while ensuring sufficient electrical isolation between antenna elements. The composite antenna comprises ground plane, first feeding point connected to ground plane, first conductor connected to first feeding point and disposed linearly symmetrically with respect to axis, second conductor connected to first conductor and disposed linearly symmetrically with respect to axis, second feeding point disposed in a position along axis, third conductor connecting second feeding point and second conductor, and fourth conductor connecting second feeding point and second conductor and disposed in a linearly symmetrical manner to third conductor with respect to axis.

Abstract: A composite antenna device includes a ground board, an unbalanced antenna, a balanced antenna. The unbalanced antenna includes a first feeding point coupled with the ground board, a first radiator having a second end and a first end connected with the first feeding point, and a load conductor connected with the second end. The balanced antenna includes a second feeding point, a second radiator connected with the second feeding point, and a third radiator connected with the second feeding point. The load conductor has a shape symmetrical about a straight line which passes through the first feeding point and which is perpendicular to the ground board. The second radiator and the third radiator are placed at positions symmetrical to each other about the straight line, respectively, and have shapes symmetrical to each other about the straight line. The composite antenna has a large isolation between the unbalanced antenna and the balanced antenna, accordingly having a small size.

Abstract: The antenna device has an antenna element, a transistor circuit connected to the antenna element, and an inductance circuit earthed to a shunt between the antenna element and the transistor circuit. The electronic device has the antenna device and a radio circuit connected to the transistor circuit.

Abstract: A composite antenna device includes a ground board, an unbalanced antenna, a balanced antenna. The unbalanced antenna includes a first feeding point coupled with the ground board, a first radiator having a second end and a first end connected with the first feeding point, and a load conductor connected with the second end. The balanced antenna includes a second feeding point, a second radiator connected with the second feeding point, and a third radiator connected with the second feeding point. The load conductor has a shape symmetrical about a straight line which passes through the first feeding point and which is perpendicular to the ground board. The second radiator and the third radiator are placed at positions symmetrical to each other about the straight line, respectively, and have shapes symmetrical to each other about the straight line. The composite antenna has a large isolation between the unbalanced antenna and the balanced antenna, accordingly having a small size.