Microwave circulator

• US 4,195,296 A
• Filed: 03/13/1978
• Issued: 03/25/1980
• Est. Priority Date: 03/14/1977
• Status: Expired due to Term

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Williams, John C.
• Primary Examiner(s): Gensler, Paul L.
• Application Number:
  US05/886,133
• Time in Patent Office: 743 Days
• Field of Search: 333/1.1, 331/9, 329/204, 343/5 PD, 343/8
• US Class Current: 342/114
• CPC Class Codes: G01S 13/62 Sense-of-movement determination G01S13/589 takes precedence
• CPC Class Codes: H01P 1/387 Strip line circulators

Abstract

A signal detection device for a Doppler radar system comprising a circulator having an input, an antenna and a detector port. The signal at the detector port comprises the echo signal received at the antenna port and a small portion of the signal to be transmitted applied at the input port, the latter having a phase which varies transversely across the detector port. The detection device further includes a pair of detectors each connected to one of two points transversely spaced across the detector port for producing output signal of a frequency corresponding to the Doppler frequency and different phase. The phase difference between the two output signals is indicative of the approach or recession of a target with respect to the radar system.

Claims

1. A signal detection device for a Doppler radar system or the like comprising a circulator having an input port for receiving a signal to be transmitted toward a target, an antenna port for supplying to an antenna of the radar the signal to be transmitted and for receiving an echo signal reflected from the target, a detector port for supplying a signal comprising the echo signal and a small portion of the signal to be transmitted transferred thereto from said input port, said portion of said signal to be transmitted at said detector port having a phase which varies transversely of said detector port, said detection device further including a first and second detector means each connected to a respective one of two points spaced transversely across said detector port for producing, from said echo signal and said portion of said signal to be transmitted, two output signals of different phase and a frequency indicative of the velocity of the target relative to the radar system, the phase difference between said output signals being indicative of approach or recession of the target with respect to the radar system.

2. The detection device according to claim 1 wherein said circulator is in the form of a microstrip pattern on a substrate of gyromagnetic material.

3. The detection device according to claim 1 or 2 wherein each of said first and second detector means includes a capacitor and a diode connected in series between the respective one of said two points and a point of common potential.

4. The detection device according to claim 1 or 2 wherein each of said detector means includes a quarter-wavelength long, open circuited microstrip section and a diode connected between one end of said microstrip section and a respective one of said two points.

5. The detection device according to claim 1 including a transmission line connected to said detector port, said two points being spaced at different distances along said transmission line.