Microwave/millimeter wave sensor apparatus

Abstract

A microwave / millimeter wave sensor apparatus can obtain sensitive detected information while attaining a simple constitution, low costs and high efficiency of power. In the sensor apparatus, a planar radiation type oscillator substrate (S1) having an inner layer GND (12) interposed between a front surface side dielectric substrate (10) and a rear surface side dielectric substrate (11) has a pair of conductor patches (4, 4) axisymmetrically on the side of a front surface layer (16). A gate (2) and a drain (3) of a microwave transistor (1) are respectively connected to the conductor patches (4,4) to supply power to the gate (2) and the drain (3) of the microwave transistor (1) by a gate-side RF choke circuit (5a) and a drain-side RF choke circuit (5b). An impedance line (9) satisfying an oscillation condition is connected to a source (8) to transmit a transmission RF signal in an RF zone as a planar radiation type oscillator and to receive a reception RF signal as reflected waves from a matter to be measured, thus obtaining an IF signal as detected information by homodyne mixing.

Description

technical field [0001] The present invention relates to transmitting signals in the microwave / millimeter wave band to an object to be measured, and detecting (such as motion detection, speed detection, presence detection, and position detection, etc.) information related to the object to be measured by receiving reflected waves from the object to be measured Microwave / millimeter wave sensor device. Background technique [0002] Conventional microwave / millimeter wave sensor devices are configured by connecting a transistor oscillator circuit or a GUNN diode oscillator circuit, a diode mixer circuit, an antenna, a coupler, a splitter, and a transmitter / receiver separation device through a transmission line such as a microstrip line. Independent functional circuits such as circulators. In such a conventional microwave / millimeter wave sensor device, the oscillation signal of the oscillation circuit is generally used as a transmission RF signal, and a part of the oscillation sig...

AI Technical Summary

Problems solved by technology

[0007] However, as in the invention described in Non-Patent Document 1, in the structure in which the GUNN diode is directly mounted in the circular conductor patch, although there is no power loss due to the transmission line, the DC / RF conversion efficiency of the GUNN diode itself is different from that of the GUNN diode. Transistors are very poor in comparison, so power consumption increases, and stable operation cannot be expected unless a high heat dissipation structure is adopted

In addition, GUNN diodes cannot expect higher RF / IF conversion gain than transistors, so they are disadvantageous in terms of detection sensitivity.

Furthermore, in the invention described in Non-Patent Document 1, although a planar conductor patch type radiation structure is adopted, a sensor device expected to have a simple structure, low cost, and high power efficiency cannot be realized.

[0008] In addition, as in the invention described in Non-Patent Document 1, an oscillation FET is arranged in the center of two semicircular conductor patches capacitively coupled by a chip capacitor, and a mixing FET is directly mounted in the drain side conductor patch. In the structure of the Schottky barrier diode, since a plurality of RF band parts are arranged in the conductor patch, it has to become a complicated structure

In addition, capacitive coupling using chip capacitors is difficult to achieve in the millimeter wave band, and Schottky barrier diodes are used for frequency mixing, so higher RF / IF conversion gains than transistors cannot be expected. This point of sensitivity is disadvantageous in

[0009] Also, as in the invention described in Non-Patent Document 3, only a microstrip line transistor oscillation circuit designed for a 50Ω load is connected to the feeding point of a square conductor patch antenna designed for a 50Ω load on the same plane. In this case, unavoidable coupling occurs between the square patch antenna and the microstrip conductor of the oscillation circuit, so the conductor pattern of the oscillation circuit affects the radiation output, radiation pattern, and oscillation frequency characteristics

The invention described in Non-Patent Document 3 has such disadvantages that it is difficult to deal with it practically.

Furthermore, the invention described in Non-Patent Document 3 is configured to connect a general microstrip square patch antenna with an input impedance of 50 ohms to a general microstrip line oscillation circuit with an output impedance of 50 ohms, so that the antenna and the oscillation circuit are not separated. Integral, especially in the millimeter wave band, it is disadvantageous in terms of efficiency because the power loss caused by the microwave band part constituting the feedback circuit for oscillation etc. increases

Images