Fault isolation in a Butler matrix fed circular phased array antenna

• US 5,086,302 A
• Filed: 04/10/1991
• Issued: 02/04/1992
• Est. Priority Date: 04/10/1991
• Status: Expired due to Term

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: Alliedsignal Inc.
• Inventors: Miller, George M.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US07/683,469
• Time in Patent Office: 300 Days
• Field of Search: 342/373, 342/173, 342/371
• US Class Current: 342/373
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices

Abstract

A method for monitoring a phased array antenna system to determine the existence of faulty components in the system and the location of such components in the system. More particularly, the invention relates to a Butler matrix-fed circular phased array antenna system wherein an individual one of the plurality of columns of the array which is faulty can be identified by comparison of a measured amplitude value to a predetermined level.

Claims

1. The method of fault isolation in a Butler matrix fed phased array antenna, said antenna including:

a plurality of radiating elements arranged in an array;

a Butler beam forming matrix connected to said radiating elements;

a plurality of variable phase shifters connected to said Butler matrix, and a distribution network for distributing energy to said radiating elements of said array, said network having an input port and a plurality of output ports, each said network output port being connected to a separate one of said phase shifters;

said method comprising;

adjusting said phase shifters to values so that only a selected first one of said radiating elements of said array is effective in delivering energy to said input port of said distribution network;

transmitting a test signal toward said array;

measuring the amplitude of the signal at said input port of said distribution network to provide a measured amplitude;

identifying said selected first radiating element as being defective whenever said measured amplitude is below a predetermined level.

2. A method as claimed in claim 1 with the additional steps of:

adjusting said phase shifters to values so that only a selected second one of said radiating elements of said array is effective in delivering energy to said input port of said distribution network;

repeating said steps of;

transmitting;

measuring; and

identifying for said second one of said radiating elements.

3. The method of fault isolation in a Butler matrix fed phased array antenna, said antenna including:

a plurality of radiating elements arranged in an array;

a Butler beam forming matrix connected to said radiating elements;

a plurality of variable phase shifters connected to said Butler matrix; and

a distribution network for distributing energy to said radiating elements of said array, said network having an input port and a plurality of output ports each said network output port being connected to a separate one of said phase shifters;

said method comprising a routine including the steps of;

adjusting said phase shifters to values so that only a selected one of said radiating elements of said array is effective in delivering energy to said input port of said distribution network;

transmitting a test signal toward said array;

detecting said test signal received by said array and delivered to said input port of said distribution network;

measuring the amplitude of said detected signal to provide a measured amplitude;

identifying said selected radiating element as being defective whenever said measured amplitude is below a predetermined level;

repeating said routine for successively different selected ones of said radiating elements of said array until all said radiating elements of said array have been tested.

4. The method of fault isolation in a Butler matrix fed phased array antenna, said antenna including:

a plurality of radiating elements arranged in an array;

a Butler beam forming matrix connected to said radiating elements;

a plurality of variable phase shifters connected to said Butler matrix; and

a distribution network for distributing energy to said radiating elements of said array, said network having an input port and a plurality of output ports, each said network output port being connected to a separate one of said phase shifters;

said method comprising;

performing a first routine when all said radiating elements of said array are known to be fully functional, said first routine including the steps of;

adjusting said phase shifters to values so that only a selected one of said radiating elements of said array is effective in delivering energy to said input port of said distribution network;

transmitting a test signal toward said array;

detecting said test signal received by said array and delivered to said input port of said distribution network;

measuring the amplitude of said detected signal to provide a reference measured amplitude;

storing said reference measured amplitude correlated with said selected radiating element;

repeating said first routine for successively different ones of said radiating elements until said reference measured amplitudes for all said radiating elements of said array have been stored;

performing a second routine when the functionality of said radiating elements of said array is to be tested, said second routine including the steps of;

adjusting said phase shifters to values so that only a selected one of said radiating elements of said array is effective in delivering energy to said input port of said distribution network;

transmitting a test signal toward said array;

detecting said test signal received by said array and delivered to said input port of said distribution network;

measuring the amplitude of said detected signal to provide a test measured amplitude;

comparing said test measured amplitude with said stored reference measured amplitude; and

identifying said selected radiating element as being faulty whenever said test measured amplitude is less than a tolerable amount below said stored reference measured amplitude for said selected radiating element;

repeating said second routine for successively different ones of said radiating elements until all said radiating elements of said array have been tested by said second routine.

5. The method of fault isolation in a Butler matrix fed phased array antenna system, said antenna system including:

a Butler matrix having a plurality of input modes and a plurality of output ports;

a plurality of radiating elements, one each of said radiating elements being connected to one each of said matrix output ports;

a plurality of variable phase shifters, one each of said phase shifters being connected to one each of said matrix input modes;

a power divider having an input port and a plurality of output ports, one each of said power divider output ports being connected to one each of said phase shifters;

a transmitter;

a receiver;

means for connecting said transmitter and said receiver to said power divider input port;

means for adjusting said phase shifters to apply calibration phases to said Butler matrix for shaping the beam formed by said antenna; and

means for ad3usting said phase shifters to apply steering phases to said Butler matrix for steering the beam formed by said antenna;

said method comprising;

adjusting said phase shifters to remove all calibration phases from said Butler matrix;

adjusting said phase shifters to apply phases to said Butler matrix corresponding to the phases applied to said Butler matrix when steering the beam of said antenna in a direction aligned with a first one of said radiating elements of said array;

transmitting a test signal toward said antenna;

recording and storing the amplitude of the output of said receiver when said first one of said radiating elements is known to be fully functional to provide a reference amplitude for said first radiating element;

repeating said steps adjusting said phase shifters to phases corresponding to steering phases, transmitting a test signal, and recording and storing the amplitude for each successive one of said radiating elements when said successive ones of radiating elements are known to be fully functional, until said reference amplitudes are stored for each said radiating element of said array;

thereafter, testing said radiating elements of said array to determine the functionality of each of said radiating elements by performing for each of said radiating elements said steps of;

adjusting said phase shifters to remove all calibration phases,

adjusting said phase shifters to phases corresponding to steering phase, and

transmitting a test signal;

comparing the amplitude of the output of said receiver obtained during a current test for each said radiating element with said stored reference amplitude for each said radiating element; and

identifying a radiating element as being faulty whenever said comparison shows the current amplitude to be less than a tolerable amount below said reference amplitude.