Method of facilitating construction of a microwave system by appropriate measurements or determination of parameters of selected individual microwave components to obtain overall system power response

• US 5,436,846 A
• Filed: 06/03/1994
• Issued: 07/25/1995
• Est. Priority Date: 05/29/1990
• Status: Expired due to Term

• Current Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Original Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Inventors: Fleming-Dahl, Arthur
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): CHOI, KYLE JAEHUN
• Application Number:
  US08/253,597
• Time in Patent Office: 417 Days
• Field of Search: 364/578, 364/580, 364/481, 364/483, 324/637, 324/638, 324/76.19
• US Class Current: 716/136
• CPC Class Codes: G01R 31/2822 of microwave or radiofrequency circuits of attenuation, gain, e.g. using network analyzers G01R27/28
• CPC Class Codes: G06F 2119/06 Power analysis or power optimisation
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods

Abstract

A method of facilitating construction of a microwave system which permits the evaluation of a variety of hardware construction options and subsequent evaluation of their effectiveness by measuring or otherwise determining appropriate physical parameters of selected components arranged in a selected order to predict the power response uses an iterative ladder network constructed according to a point discontinuity model for individual components of the system in which input and output reflection coefficients and an attenuation coefficient are calculated for each component based on measured or specified insertion loss and VSWR or return loss values, and the ladder is analyzed by processing the coefficients forward in the direction of power flow.

Claims

1. A method of providing data and analyzing the data in order to determine the overall Dower response of a microwave system, comprising the steps of gathering the data and analyzing the data, wherein the step of gathering data comprises the steps of:

(A) providing first, second, and third individual microwave components each possessing an insertion loss, a return loss, and a voltage standing wave ratio (VSWR);

(B) establishing an order of said first, second, and third individual microwave components;

(C) measuring said insertion loss and also measuring one of said VSWR and return loss of said first, second, and third individual microwave components;

(D) modifying said order of said first, second, and third individual microwave components depending on results Obtained by said step of measuring the insertion loss and one of said VSWR and return loss of said first, second, and third individual microwave components; and

measuring at least two third individual microwave component physical characteristics representative of the amount by which power to the third individual microwave component is lost, reflected, and transmitted;

(f) deriving, using a computer, from said third individual microwave component factors T², R², and L², reflection point coefficients r² and attention point coefficient Av² for said third individual microwave component;

(g) constructing an iterative ladder network which represents the first, second, and third individual microwave components, in the selected order, as made up of a sequence of segments, each segment being represented by an nth one of said reflection point coefficients r(n²) and an nth one of said attenuation point coefficients A(n)², where n designates the number of the segment in the sequence;

(h) processing, using a computer, the reflected coefficients r(n)² for each segment and the attenuation coefficients A(n)² for each segment in order in the direction of power flow, to obtain a system power transmission factor T(n)² and a system power reflection factor R(n)² which accounts for the first n segments of the system;

(i) comparing the system power transmission factor and power reflection factor with a predetermined power transmission factor and a predetermined power reflection factor; and

(j) if the difference between respective system and predetermined factors is not acceptable, repeating at least steps (a)-(i) for a different first individual microwave component.

2. A method as claimed in claim 1, wherein step (d) further comprises the step of obtaining a system power loss factor L(n)² which accounts for the first n components of the system.

3. A method as claimed in claim 2, wherein said step of obtaining a loss factor is accomplished by using the conservation of power formula L(n)² =1-T(n)² -R(n)².

4. A method as claimed in claim 1, wherein step (d) comprises the steps of:

(i) calculating a first iterative system level transmission coefficient T(1) and a first iterative system level reflection coefficient R(1) as a function of r(1) and A(1), wherein r(1) is the input reflection point coefficient for the first component and A(1) is an artificial attenuation point coefficient placed at the input of the first component, the value of A(1) being set equal to 1;

(ii) calculating a second iterative system level transmission coefficient T(2) and a second iterative system level reflection coefficient R(2) as a function of r(2) and A(2), wherein r(2) is the output reflection coefficient of the first component, assumed to be equal to r(1), and A(2) is the attenuation coefficient for the first component;

(iii) repeating steps (i) and (ii) for each component in the system by calculating the nth iterative system power transmission factor T(n)² and the nth iterative system power reflection factor R(n)².

5. A method as claimed in claim 4, wherein A(n)=1 for n=an odd number.

6. A method as claimed in claim 4, wherein the nth iterative reflection contribution to the system reflection factor R(n) is multiplied by the second previous power transmission factor T(n-2)² prior to its inclusion in R(n).

7. A method as claimed in claim 4, wherein an iterative system loss factor L(n) is calculated each time step (d) is performed, which contains as part of the contribution from the nth iterative segment the nth iterative reflection contribution to the system reflection factor R(n), multiplied by (1-T(n-2)²).

8. A method as claimed in claim 4, wherein the nth iterative transmission factor is calculated according to the formula:

##EQU17##

9. A method as claimed in claim 4, wherein the nth iterative reflection factor is calculated according to the formula:

##EQU18##

10. A method as claimed in claim 4, wherein an iterative loss factor is calculated each time step (d) is performed, according to the formula:

##EQU19##

11. A method as claimed in claim 1, wherein step (d) comprises the steps of:

(i) calculating a first iterative system level transmission coefficient T(1) and a first iterative system level reflection coefficient R(1) as a function of r(1) and A(1), wherein r(1) is the input reflection point coefficient for the first component and A(1) is the attenuation point coefficient for the first component;

(ii) calculating a second iterative system level transmission coefficient T(2) and a second iterative system level reflection coefficient R(2) as a function of r(2) and A(2), wherein r(2) is the output reflection coefficient of the first component assumed to be equal to r(1) and A(2) is an artificial attenuation coefficient placed at the output of the first component, the value of A(2) being set equal to 1; and

(iii) repeating steps (i) and (ii) for each component in the system by calculating the nth iterative transmission factor T(n)² and the nth iterative reflection factor R(n)².

12. A method as claimed in claim 11, wherein A(n)=1 for n=an even number.

13. A method as claimed in claim 11, wherein the nth iterative reflection contribution to the system reflection factor R(n) is multiplied by the second previous power transmission factor T(n-2)² prior to its inclusion in R(n).

14. A method as claimed in claim 11, wherein an iterative system loss factor L(n) is calculated each time step (d) is performed, which contains as part of [the]a contribution to L(n) from the nth iterative segment the nth iterative reflection contribution to the system reflection factor R(n), multiplied by (1-T(n-2)²).

15. A method as claimed in claim 11, wherein the nth iterative transmission factor is calculated according to the formula:

##EQU20##

16. A method as claimed in claim 11, wherein the nth iterative reflection factor is calculated according to the formula:

##EQU21##

17. A method as claimed in claim 11, wherein an iterative loss factor is calculated each time step (d) is performed, according to the formula:

##EQU22##

18. A method as claimed in claim 4, or claim 11, wherein the input and output reflection coefficients for each component are assumed to be equal.

19. A method as claimed in claim 1, wherein step (a) further comprises the steps of calculating T, R, and L for each component according to the following relationships:

##EQU23##

20. A method as claimed in claim 1, wherein step (a) further comprises the steps of calculating R, T, and L according to the following relationships:

space="preserve" listing-type="equation">T=10.sup.IL/20

space="preserve" listing-type="equation">R=10.sup.RL/20

space="preserve" listing-type="equation">L=SQRT(1-(T.sup.2 +R.sup.2)).

21. A method as claimed in claim 1, wherein step (b) comprises the steps of deriving r according to the following formula:

##EQU24##

22. A method as claimed in claim 21, wherein Av is determined according to the following formula:

##EQU25##

23. A method as claimed in claim 1, wherein step (b) comprises the step-s of deriving r according to the following formula:

##EQU26##

24. A method as claimed in claim 21 or claim 23, wherein Av is determined according to the following formula:

##EQU27##

25. A method as claimed in claim 21 or claim 23, wherein step (b) further comprises the steps of determining r² for a lowest loss attenuator or a shortest cable, and using those values of r² to determine Av² according to the following formula:

##EQU28##

26. A method as claimed in claim 21 or claim 23, wherein step (b) further comprises the steps of determining r² for the lowest loss attenuator and shortest cable and using those values of r.sup. to determine Av according to the following formula:

##EQU29## when T is less than 0.1.

27. A method as claimed in claim 1, wherein step (c) further comprises the step of constructing the first segment from an artificial attenuation coefficient having a value of 1 and from an input reflection coefficient of the first component in the sequence.

28. A method as claimed in claim 27, wherein step (c) further comprises the step of constructing the second segment from an attenuation coefficient and an output reflection coefficient of the first component.

29. A method as claimed in claim 1, wherein step (c) further comprises the step of constructing the last segment of the ladder network from an output reflection coefficient of the last component in the sequence and from an artificial attenuation coefficient having a value of 1.

30. A method as claimed in claim 1, wherein step (c) further comprises the step of constructing the last segment of the ladder network from an output reflection coefficient of the last component in the sequence and from an artificial attenuation coefficient having a value of zero.

31. A method of providing data for an algorithm which determines the overall power response of a microwave system, comprising the steps of:

a) providing first, second, and third individual microwave components each possessing an insertion loss and a voltage standing wave ratio (VWR);

b) establishing an order of said first, second, and third individual microwave components;

c) measuring said insertion loss and VSWR of said first, second, and third individual microwave components;

d) modifying said order of said first, second, and third individual microwave components depending on results obtained in said step of measuring the insertion loss and VSWR of said first, second, and third individual microwave components; and

(e) determining a direction of power flow for the first, second, and third individual microwave components in aid order.