Monostatic homodyne radar system

• US 5,872,537 A
• Filed: 03/19/1997
• Issued: 02/16/1999
• Est. Priority Date: 03/19/1996
• Status: Expired due to Term

• Current Assignee: Infineon Technologies AG
• Original Assignee: Siemens AG
• Inventors: Siweris, Heinz-Juergen
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/822,569
• Time in Patent Office: 699 Days
• Field of Search: 342/28, 342/89, 342/124, 342/128, 342/175, 342/200, 342/82
• US Class Current: 342/128
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/034 Duplexers switching devices for waveguides H01P1/10; transmit-receive switching in transceivers H04B1/44
• CPC Class Codes: G01S 7/036 involving a transfer mixer
• CPC Class Codes: H04B 1/408 the transmitter oscillator frequency being identical to the receiver local oscillator frequency

Abstract

Monostatic homodyne radar system, in particular for continuous wave operation, in which one input port of a balanced mixer (2) is connected to an oscillator (1) and another input port of the mixer is connected to an antenna (3). The mixer has a directional coupler with a 90° phase difference between the coupling arms. The load impedances of the coupling arms have a reflection factor greater than 0.3, so that coupling of the power supplied from the oscillator to the antenna ensues, which coupling is sufficient for the radiation.

Claims

1. A monostatic homodyne radar system, comprising:

an oscillator for producing a radio-frequency signal;

a balanced mixer having first and second input ports and one output port;

an antenna;

the first input port of the mixer connected to the oscillator and the second input port of the mixer connected to the antenna;

the mixer having a directional coupler with a 90°

phase difference between coupling arms thereof;

the directional coupler having first and second inputs that form the first and second ports, respectively, of the mixer, and having first and second outputs;

the first and second outputs of the directional coupler being terminated with impedances such that a reflection factor results that is at least large enough that coupling of power emitted by the oscillator occurs between the first and second input ports of the mixer, which coupling provides for a provided transmission power.

2. The radar system according to claim 1, wherein the reflection factor is at least 0.3.

3. The radar system according to claim 1, wherein the mixer has first and second transformation networks, each of the transformation networks having an input and an output, wherein an input of each of the transformation networks is respectively connected to the first and second output, respectively, of the directional coupler, and wherein an output of each of the transformation networks is respectively connected to a non-linear circuit element, and wherein the transformation networks effect the reflection factor at the first and second outputs of the directional coupler.

4. The radar system according to claim 1, wherein the mixer has non-linear circuit elements that are directly connected to the first and second outputs of the directional coupler, and that are structured so that the reflection factor is produced.

5. The radar system according to claim 1, wherein the radar system further comprises a modulated radio-frequency signal.

6. A monostatic homodyne radar system, comprising:

an oscillator for producing a radio-frequency signal;

a balanced mixer having first and second input ports and one output port;

an antenna;

the first input port of the mixer connected to the oscillator and the second input port of the mixer connected to the antenna;

the mixer having a directional coupler with a 90°

phase difference between coupling arms thereof;

the directional coupler having first and second inputs that form the first and second ports, respectively, of the mixer, and having first and second outputs;

the first and second outputs of the directional coupler being terminated with first and second impedances, respectively, such that a reflection factor results that effects coupling of power emitted by the oscillator between the first and second input ports of the mixer, which coupling provides a predetermined transmission power;

the mixer having first and second transformation networks, each of the transformation networks having an input and an output, a respective input of each of the transformation networks is respectively connected to the first output and second output, respectively, of the directional coupler, and a respective output of each of the transformation networks respectively connected to first and second non-linear circuit elements, respectively, and wherein the transformation networks effect the reflection factor at the first and second outputs of the directional coupler.

7. The radar system according to claim 6, wherein the reflection factor is at least 0.3.

8. The radar system according to claim 6, wherein the non-linear circuit elements are directly connected to the first and second outputs of the directional coupler, and are structured such that the reflection factor is produced.

9. The radar system according to claim 6, wherein the radar system further comprises a modulated radio-frequency signal.

10. A monostatic homodyne radar system, comprising:

an oscillator for producing a radio-frequency signal;

a balanced mixer having first and second input gates and one output port;

an antenna;

the first input port of the mixer connected to the oscillator and the second input port of the mixer connected to the antenna;

the mixer having a directional coupler with a 90°

phase difference between coupling arms thereof;

the directional coupler having first and second inputs that form the first and second ports, respectively, of the mixer, and having first and second outputs;

the first and second outputs of the directional coupler being terminated with first and second impedances, respectively, such that a reflection factor results that effects coupling of power emitted by the oscillator between the first and second input ports of the mixer, which coupling provides for a predetermined transmission power;

the mixer having first and second transformation networks, each of the transformation networks having an input and an output, a respective input of each of the transformation networks respectively connected to the first output and second output, respectively, of the directional coupler, and a respective output of each of the transformation networks respectively connected to first and second non-linear circuit elements, respectively, whereby the transformation networks effect the reflection factor at the first and second outputs of the directional coupler;

the first and second non-linear circuit elements directly connected to the first and second outputs, respectively, of the directional coupler, and structured such that the reflection factor is produced.

11. The radar system according to claim 10, wherein the reflection factor is at least 0.3.

12. The radar system according to claim 10, wherein the radar system further comprises a modulated radio-frequency signal.