In one example, a signal processing circuit including a directional coupler and a termination part is disclosed. The directional coupler includes a main line as a transmission path of an RF signal and a sub-line constituting a coupled line together with the main line. The termination part includes devices connectable between ground and a first port at an end of the sub-line. The signal processing circuit switches, depending on a frequency of the RF signal, the devices of the termination part to be connected to the first port. The phase of a return signal of a signal input as a coupling signal to the termination part via the first port is opposite to the phase of an isolation signal supplied to a second port at the other end of the sub-line and connected to an output port of the coupling signal.

As a layout requirement imposed on an in-phase corporate-feed circuit, there is provided only a layout requirement to equalize the electric length of a transmission line (4) between one of N T-branch units (6) which is m-th when counted from a start point of a path A, and another one of the T-branch units (6) which is (m+1)-th when counted from the start point of the path A, to that of a transmission line (8) between one of N T-branch units (10) which is m-th when counted from an end point of a path B, and another one of the T-branch units (10) which is (m+1)-th when counted from the end point of the path B. Therefore, the in-phase corporate-feed circuit can be formed in a space smaller than that in which its circuit configuration of tournament type is formed, and downsizing of the circuit size can be achieved.

As a layout requirement imposed on an in-phase corporate-feed circuit, there is provided only a layout requirement to equalize the electric length of a transmission line (4) between one of N T-branch units (6) which is m-th when counted from a start point of a path A, and another one of the T-branch units (6) which is (m+1)-th when counted from the start point of the path A, to that of a transmission line (8) between one of N T-branch units (10) which is m-th when counted from an end point of a path B, and another one of the T-branch units (10) which is (m+1)-th when counted from the end point of the path B. Therefore, the in-phase corporate-feed circuit can be formed in a space smaller than that in which its circuit configuration of tournament type is formed, and downsizing of the circuit size can be achieved.

A bi-directional coupler includes a first individual directional coupler and a second individual directional coupler, which are individual electronic components having mutually equivalent circuit configurations. Each of the first and second individual directional couplers includes: a first terminal; a second terminal; a third terminal; a fourth terminal; a main line connecting the first terminal and the second terminal; and a subline connecting the third terminal and the fourth terminal. The subline includes first and second coupling line sections configured to be electromagnetically coupled to the main line, and a matching section provided between the first and second coupling line sections. The second terminal of the second individual directional coupler is electrically connected to the second terminal of the first individual directional coupler.

A bi-directional coupler includes a first individual directional coupler and a second individual directional coupler, which are individual electronic components having mutually equivalent circuit configurations. Each of the first and second individual directional couplers includes: a first terminal; a second terminal; a third terminal; a fourth terminal; a main line connecting the first terminal and the second terminal; and a subline connecting the third terminal and the fourth terminal. The subline includes first and second coupling line sections configured to be electromagnetically coupled to the main line, and a matching section provided between the first and second coupling line sections. The second terminal of the second individual directional coupler is electrically connected to the second terminal of the first individual directional coupler.

The present disclosure discloses a dielectric resonant antenna based NMOSFET terahertz detector, comprising an on-chip dielectric resonant terahertz antenna, wherein the on-chip dielectric resonant terahertz antenna is connected to a matching network, the matching network is connected to a source of an NMOSFET, and a gate of the NMOSFET is sequentially connected to a first bias resistor and a first bias voltage, a third transmission line is connected between the first bias resistor and the gate, a drain of the NMOSFET is connected to a first DC blocking capacitor, the other end of the first DC blocking capacitor is connected to a low noise preamplifier, a second bias resistor and a second bias voltage are connected in parallel between the first DC blocking capacitor and the low noise preamplifier, and the low noise preamplifier is further provided with a voltage feedback loop. The present disclosure also discloses a design method for the same.

A waveguide circuit (1) includes a first waveguide tube (10), a second waveguide tube (20), and a third waveguide tube (30). The first waveguide tube (10), the second waveguide tube (20), and the third waveguide tube (30) have cross-sectional shapes to allow propagation of TE modes. The tube axis of the second waveguide tube (20) is parallel to the tube axis of the first waveguide tube (10). One of the narrow sidewalls of the second waveguide tube (20) faces a narrow sidewall (10s) of the first waveguide tube (10). The third waveguide tube (30) includes a coupler that connects a hollow guide of the third waveguide tube (30) to a hollow guide of the first waveguide tube (10) and a hollow guide of the second waveguide tube (20).

A waveguide circuit (1) includes a first waveguide tube (10), a second waveguide tube (20), and a third waveguide tube (30). The first waveguide tube (10), the second waveguide tube (20), and the third waveguide tube (30) have cross-sectional shapes to allow propagation of TE modes. The tube axis of the second waveguide tube (20) is parallel to the tube axis of the first waveguide tube (10). One of the narrow sidewalls of the second waveguide tube (20) faces a narrow sidewall (10s) of the first waveguide tube (10). The third waveguide tube (30) includes a coupler that connects a hollow guide of the third waveguide tube (30) to a hollow guide of the first waveguide tube (10) and a hollow guide of the second waveguide tube (20).

A rectangular waveguide device is provided. The rectangular waveguide device comprising: a first broad wall; a second broad wall parallel to the first broad wall; a first narrow wall perpendicular to and connected to the first broad wall and the second broad wall; a second narrow wall parallel to the first narrow wall and connected to the first broad wall and the second broad wall; and at least one slot in the first broad wall.

A rectangular waveguide device is provided. The rectangular waveguide device comprising: a first broad wall; a second broad wall parallel to the first broad wall; a first narrow wall perpendicular to and connected to the first broad wall and the second broad wall; a second narrow wall parallel to the first narrow wall and connected to the first broad wall and the second broad wall; and at least one slot in the first broad wall.