Wideband dual directional coupler

A dual directional coupler comprising:

• first, second, third, and fourth ports;
• a main transmission line connecting the first and second ports;
• a first coupling circuit unit coupled to the main transmission line and outputting a first coupled signal for a signal input to the first port to the third port;
• and
• a second coupling circuit unit coupled to the main transmission line and outputting a second coupled signal for a signal input to the second port to the fourth port,
• wherein the first coupling circuit unit comprises:
• a first coupled line coupled horizontally from the main transmission line and acquiring a portion of a signal traveling from the first port to the second port;
• a first equalizer;
• a transmission line 1-1 connecting one end of the first coupled line to one end of the first equalizer;
• a transmission line 1-2 connecting the other end of the first equalizer to the third port;
• and
• a first matching resistor connected to the other end of the first coupled line, and
• wherein the second coupling circuit unit comprises:
• a second coupled line coupled horizontally from the main transmission line and acquiring a portion of a signal traveling from the second port to the first port;
• a second equalizer;
• a transmission line 2-1 connecting one end of the second coupled line to one end of the second equalizer;
• a transmission line 2-2 connecting the other end of the second equalizer to the fourth port;
• and
• a second matching resistor connected to the other end of the second coupled line.