Microwave Sensor Integrating Oscillator and Mixer
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Solution Overview
Problem
Conventional microwave/millimeter wave sensor apparatuses face limitations in high-density circuit integration due to losses in connecting portions and transmission lines, leading to degraded performance, particularly in millimeter wave bands, and struggle with achieving high sensitivity, power efficiency, and a simple, cost-effective structure.
Innovation Solution
A microwave/millimeter wave sensor apparatus with a radiation type oscillator integrating a three-electrode high-frequency amplifying device, utilizing an RF choke circuit and IF-band loading unit for direct-current bias and signal processing, and incorporating resonating cavities for oscillation stabilization and improved radiation directivity, along with a frequency selective filtering unit to enhance detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If individual functional circuits are connected with transmission lines to form conventional microwave/millimeter wave sensor apparatus, then circuit functionality is achieved, but loss due to connecting portions and transmission lines degrades circuit performance
Solution Approach 1:
The patent merges the oscillating circuit and mixer circuit into a single integrated structure, eliminating the need for transmission lines and connecting portions between these functional blocks. This integration directly reduces energy loss and improves circuit performance by removing the intermediate lossy connections.
2Loss of energy
If GUNN diode is mounted directly inside round conductor patch to eliminate transmission line loss, then transmission line loss is reduced, but DC-RF conversion efficiency becomes much lower and power consumption increases
Solution Approach 1:
The patent replaces the GUNN diode with a transistor, which offers superior DC-RF conversion efficiency and lower power consumption. The transistor achieves both low transmission line loss (through direct integration) and high power efficiency, effectively substituting a less efficient component with a more efficient one.
3Measurement precision
If GUNN diode or Schottky barrier diode is used for mixing, then mixing function is achieved, but RF-IF conversion gain is limited and detection sensitivity cannot be improved
Solution Approach 1:
The patent changes the fundamental parameter of the mixing device from a diode-based mixer to a transistor-based mixer. This parameter change enables higher RF-IF conversion gain and improved detection sensitivity, as the transistor provides better amplification characteristics compared to diode mixers.
4Power
If conventional rectangular conductor patch antenna is connected to microstrip line transistor oscillating circuit, then oscillation and radiation functions are achieved, but coupling between antenna and oscillating circuit affects radiation output and radiation pattern
Solution Approach 1:
The patent merges the antenna and oscillating circuit into a single integrated structure where the transistor is directly mounted on the conductor patch. This eliminates the coupling effects between separate antenna and oscillating circuit components, stabilizing the radiation pattern and output by removing the interaction between distinct electromagnetic structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves high RF-IF conversion efficiency, enabling highly-sensitive sensing information acquisition while maintaining a simple structure, low costs, and high power efficiency, with integrated functions of RF transmission, reception, oscillation, mixing, and amplification.
Implementation Method 1
a radiation type oscillator that integrates a three-electrode high-frequency amplifying device to generate negative resistance
Implementation Method 2
causes the amplifying device to share the antenna function to emit electromagnetic wave to space
Implementation Method 3
The radiation type oscillator receives the receive RF signal, and obtains an IF signal through homodyne mixing performed by the radiation type oscillator
Implementation Method 4
resonating cavities for oscillation stabilization
Implementation Method 5
an RF choke circuit that allows direct-current bias voltage and IF signals to pass, and blocks RF signals
Implementation Method 6
a frequency selective filtering unit to enhance detection sensitivity
Data Source
Figure 1A~1C
Figure 2
Figure 3~4
AI summary
The present invention relates to a microwave/millimeter wave sensor apparatus that can obtain highly-sensitive sensing information, while being a simple structure, being inexpensive, and having high power efficiency. In the microwave/millimeter wave sensor apparatus according to this invention, 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) in an axis-symmetric manner on the side of the 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) through 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) and a transmit RF signal in an RF zone as a planar radiation type oscillator is transmitted and a receive RF signal as reflected waves is received from a measured object, thus obtaining an IF signal as the sensing information through homodyne mixing.