Low cost millimeter wave imager

A millimeter-wave imaging sensor comprising:

• a focal plane array detector at a focus of an objective lens and on a printed circuit board,
• wherein the focal plane array detector comprises horn antennas for focusing incident waves onto backward tunneling diodes without an intervening active component between each horn antenna and a corresponding one of the backward tunneling diodes, each of the backward tunneling diodes corresponding to one of the horn antennas, and
• wherein the printed circuit board comprises:
• a quartz substrate having a thickness of one quarter wavelength of a millimeter wave;
• a metal pattern on a side of the quartz substrate corresponding to an input side of the printed circuit board, the metal pattern comprising bonding pads for coupling the focal plane array detector to the printed circuit board;
• and
• a plurality of vias through the quartz substrate for routing a signal from the input side to electrical connections for readout circuitry located on an output side of the printed circuit board,
• wherein the output side is opposite to the input side.

A wave detector module comprising:

• a flip chip;
• a backward tunneling diode wave detector on the flip chip, the flip chip being on a surface of a printed circuit board;
• electrical connections for readout electronics coupled to the flip chip;
• and
• a horn antenna coupled to the flip chip, the horn antenna having an inlet rectangular cross-section substantially parallel with said surface of the printed circuit board,
• wherein the flip chip, the electrical connections, and the backward tunneling diode are configured to function together as an imaging sensor,
• wherein the flip chip is at a focal plane of a focusing lens, and
• wherein the printed circuit board comprises:
• a quartz substrate having a thickness of one quarter wavelength of a millimeter wave;
• a metal pattern on a side of the quartz substrate corresponding to said surface of the printed circuit board, the metal pattern comprising bonding pads for coupling the flip chip to the printed circuit board;
• and
• a plurality of vias formed through the quartz substrate for routing a signal from said surface to the electrical connections located on an output side of the printed circuit board,
• wherein the output side is opposite to said surface.

A method of detecting low power waves for use by readout circuitry, the method comprising:

• receiving wave energy by a horn antenna, the horn antenna having an inlet and a throat, the inlet having a rectangular cross-section;
• directing the wave energy toward a backward tunneling diode detector on a printed circuit board within the throat without an intervening active component between the horn antenna and the backward tunneling diode detector, the printed circuit board being substantially parallel with the inlet rectangular cross-section;
• detecting the wave energy by the backward tunneling diode detector, the backward tunneling diode detector operating near zero bias voltage;
• and
• providing detected wave energy signals to the readout circuitry,
• wherein the printed circuit board comprises:
• a quartz substrate having a thickness of one quarter wavelength of a millimeter wave;
• a metal pattern on a side of the quartz substrate corresponding to an input side of the printed circuit board, the metal pattern comprising bonding pads for coupling the backward tunneling diode detector to the printed circuit board;
• and
• a plurality of vias through the quartz substrate for routing a signal from the input side to electrical connections located on an output side of the printed circuit board,
• wherein the output side is opposite to the input side.