Reflection coefficient measurements

• US 4,427,936 A
• Filed: 06/22/1981
• Issued: 01/24/1984
• Est. Priority Date: 06/22/1981
• Status: Expired due to Fees

• Current Assignee: Microwave Development Labs Incorporated
• Original Assignee: Microwave Development Labs Incorporated
• Inventors: Riblet, Gordon P., Hansson, Bertil E. R.
• Primary Examiner(s): Gensler, Paul L.
• Application Number:
  US06/275,927
• Time in Patent Office: 946 Days
• Field of Search: 324/58 B, 324/58.5 B, 333/120, 333/123, 333/125, 333/127, 333/128, 333/136, 333/137, 333/1.1
• US Class Current: 324/638
• CPC Class Codes: G01R 27/04 in circuits having distributed constants , e.g. having very long conductors or involving high frequencies

Abstract

A compact apparatus for the accurate measurement of complex reflection coefficients and VSWR of a device over a bandwidth of an octave or greater by preferably measuring three power levels at detectors associated with the device. The device is formed by the junction of 5 transmission lines two of which are used for receiving a test signal and for transmitting the signal to the device being measured. The other three transmission lines are connected to detector arms each having a detector associated therewith. The techniques of the invention are embodied herein in a waveguide embodiment, a stripline embodiment and a microstrip embodiment of the invention.

Claims

1. A matched lossless reciprocal power divider used for the measurement of reflection coefficient and comprising;

means defining a common central resonator junction having only five ports,

a transmission line associated with each port,

only five matching means associated respectively with the five transmission lines intercoupling each transmission line to a port of the resonator junction,

first, second and third power level detectors,

a first of said ports receiving a test signal,

a second of said ports coupling to a device being measured,

third, fourth and fifth of said ports coupling, respectively, to said first, second and third power level detectors,

and a directional coupler associated with the transmission line coupling to the first port and including means coupled from the coupler for monitoring the incident power coupled to the resonator junction.

2. A matched reciprocal power divider as set forth in claim 1 wherein each matching network comprises a matching transformer.

3. A matched reciprocal power divider as set forth in claim 1 having five fold rotational symmetry.

4. A matched reciprocal power divider as set forth in claim 1 made in stripline construction.

5. A matched reciprocal power divider as set forth in claim 1 made in waveguide construction.

6. A matched reciprocal power divider as set forth in claim 1 made in microstrip construction.

7. A matched reciprocal power divider as set forth in claim 1 wherein said means coupled from the coupler for monitoring the incident power comprises a reference detector.

8. A matched reciprocal power divider as set forth in claim 1 wherein all ports are disposed radially of the central resonator junction and are substantially planar.

9. A matched reciprocal power divider as set forth in claim 1 wherein the central resonator junction has the transmission lines coupled therewith in a spaced relationship from one to the next transmission line.

10. A matched reciprocal power divider as set forth in claim 9 wherein said central resonator junction has separate peripheral wall segments interconneting the ports one to the next adjacent.

11. A matched reciprocal power divider as set forth in claim 1 wherein reflection coefficient is established in accordance with the following equations:

##EQU5## wherein P₁, P₂ and P₃ are normalized powers corresponding respectively to said first, second and third power level detectors and θ

is the angle associated with the quantity |Γ

|.

12. A matched lossless reciprocal power divider used for the measurement of reflection coefficient and comprising;

five transmission lines defining five ports of the divider, one of said ports forming an input port and at least another of said ports forming an output port,

a central resonator region,

means intercoupling the transmission lines to the central resonator region to enable power division between the input and output ports,

said central resonator having the transmission lines coupled therewith in a spaced relation from one to the next transmission line,

first, second and third power level detectors,

means coupling the the first, second and third power level detectors to the remaining three ports, respectively,

and a directional coupler associated with the transmission line coupling to the one port and including means coupled from the coupler for monitoring the incident power coupled to the resonator region.

13. A matched reciprocal power divider as set forth in claim 12 wherein the divider is characterized by five fold rotational symmetry.

14. A matched reciprocal power divider as set forth in claim 13 wherein said means coupled from the coupler for monitoring the incident power comprises a reference detector.

15. A matched reciprocal power divider as set forth in claim 12 wherein each matching network comprises a matching transformer.

16. A matched reciprocal power divider as set forth in claim 12 made in stripline construction.

17. A matched reciprocal power divider as set forth in claim 12 made in waveguide construction.

18. A matched reciprocal power divider as set forth in claim 12 made in microstrip construction.

19. A matched reciprocal power divider as set forth in claim 12 wherein the divider has only five ports.

20. A matched reciprocal power divider as set forth in claim 12 wherein all ports are disposed radially of the central resonator junction and are disposed in a substantially planar interrelationship.

21. A matched reciprocal power divider as set forth in claim 12 wherein the central resonator junction has separate peripheral wall segments interconnecting the ports one to the next adjacent port.

22. A matched reciprocal power divider as set forth in claim 12 wherein reflection coefficient is established in accordance with the following equations:

##EQU6## wherein P₁, P₂ and P₃ are normalized powers corresponding respectively to said first, second and third power level detectors and θ

is the angle associated with the quantity |Γ

|.