Oscillator
An oscillator configured to oscillate an electromagnetic wave, including: a negative resistance device; a microstrip resonator configured to determine an oscillation frequency of an electromagnetic wave excited by the negative resistance device; a resistance device and a capacitance device, which form a low-impedance circuit configured to suppress parasitic oscillation; and a strip conductor configured to connect the capacitance device of the low-impedance circuit and the microstrip resonator to each other, in which an inductance L of the strip conductor and a capacitance C of the microstrip resonator produce a resonance frequency of ½π√LC, and ¼ of an equivalent wavelength of the resonance frequency is larger than a distance between the negative resistance device and the resistance device of the low-impedance circuit via the strip conductor, is provided.
1. An oscillator configured to oscillate an electromagnetic wave, comprising:
a negative resistance device;
a microstrip resonator configured to determine an oscillation frequency of an electromagnetic wave excited by the negative resistance device;
a resistance device and a capacitance device, which form a low-impedance circuit configured to suppress parasitic oscillation; and
a strip conductor configured to connect the capacitance device of the low-impedance circuit and the microstrip resonator to each other,
wherein an inductance L of the strip conductor and a capacitance C of the microstrip resonator produce a resonance frequency of ½π√LC, and ¼ of an equivalent wavelength of the resonance frequency is larger than a distance between the negative resistance device and the resistance device of the low-impedance circuit via the strip conductor.
2. The oscillator according to claim 1 , further comprising a bias circuit that comprises a power source and a wiring, the power source being configured to adjust an operating point voltage of the negative resistance device.
3. The oscillator according to claim 1 , wherein the strip conductor includes a part having a meander shape.
4. The oscillator according to claim 1 , wherein the strip conductor is short-circuited in part.
5. The oscillator according to claim 1 , wherein the microstrip resonator comprises a patch antenna.
6. A measuring apparatus configured to measure information on an object, comprising:
the oscillator according to claim 1 configured to emit an electromagnetic wave; and
a receiver configured to detect the electromagnetic wave from the object.
7. The oscillator according to claim 4 , further comprising a short-circuit portion which connects the middle of the strip conductor and the capacitor.
8. The oscillator according to claim 7 , wherein the short-circuit portion is made so that oscillation at a distributed-constant resonance frequency different from the resonance frequency is disabled or suppressed.
9. The oscillator according to claim 1 , wherein the capacitance device has a MIM structure, and
the resistance device is embedded at an internal position of the MIM structure.
10. The oscillator according to claim 1 , wherein the resistance device is connected at the middle of the strip conductor.
11. The oscillator according to claim 10 , wherein the resistance device is disposed between the capacitance device and the microstrip resonator.
12. The oscillator according to claim 1 , wherein the low-impedance circuit is made so that the whole parasitic oscillation is suppressed in a frequency region of DC or higher and lower than a desired oscillation frequency of the microstrip resonator.