A hybrid coupler is disclosed. The hybrid coupler includes a printed circuit board. The printed circuit board includes at least two input ports, at least two output ports, and a plurality of couplers, each coupler of the plurality of couplers comprising first and second transmission traces and a coupling junction connecting the first and second transmission traces. The plurality of couplers are electrically coupled in series between the input ports and the output ports. The hybrid coupler further includes a defective ground structure below the coupling junction of at least one of the plurality of couplers.

The present disclosure relates generally to radio engineering, and for example, to high-rate wireless data transfer between different printed circuit boards or between parts of the same printed circuit board. The technical result is easier fabrication, smaller dimensions, lower losses at high frequencies and improved performance. According to the disclosure, a wireless data transfer system comprises: two printed circuit boards separated by an air gap, between which a transverse electromagnetic (TEM) mode waveguide is formed, wherein each printed circuit board includes a converter structure configured to: perform conversion between the signal transmission line mode and TEM mode in the waveguide, connected to an RF component; wherein the converter structure includes: an antenna, a signal transmission line between the antenna and the RF component, and at least one reflector configured to provide directive propagation of the TEM mode in the waveguide; wherein the width of the air gap between the printed circuit boards does not exceed /4, where is the wavelength of the transmitted signal.

An electronic filter includes a ground plane and a top conductor overlying the ground plane. The top conductor includes an input and an output for receiving and outputting signals, respectively. The filter further includes a plurality of unit cells arranged in series along the top conductor. Each of the plurality of unit cells includes a planar structure disposed between the top conductor and the ground plane. Each of the plurality of unit cells further includes a pair of vias connecting the planar structure to the ground plane.

A hybrid coupler is disclosed. The hybrid coupler includes a printed circuit board. The printed circuit board includes at least two input ports, at least two output ports, and a plurality of couplers, each coupler of the plurality of couplers comprising first and second transmission traces and a coupling junction connecting the first and second transmission traces. The plurality of couplers are electrically coupled in series between the input ports and the output ports. The hybrid coupler further includes a defective ground structure below the coupling junction of at least one of the plurality of couplers.

An antenna device includes a board including a conductor layer, a first conductor pattern arranged on a surface of the board, a connecting section that connects the first conductor pattern to the conductor layer, a second conductor pattern that has one end side connected to one end side of the first conductor pattern and has a length which is equal to or longer than approximately of an operating wavelength, multiple first electromagnetic bandgap elements arranged on both sides of the first conductor pattern in a longitudinal direction on the board, multiple second electromagnetic bandgap elements arranged on both sides of the second conductor pattern in a longitudinal direction on the board, a conductor plate that faces the first conductor pattern, and a third conductor pattern that has one end side connected to another end side of the second conductor pattern and is arranged on the surface of the board.