Calibration system for wide band array using true-time-delay beamsteering

A method for testing a wide band microwave array antenna system operating over a frequency band, the array system comprising a plurality of true-time-delay (TTD) time shifters in a plurality of time shift channels, comprising:

• transmitting a large number of test excitation signals at frequencies covering said frequency band through said time shift channels to thereby synthesize the generation of a very short pulse;
• offsetting the arrival times of the signals through the time shift channels to maintain separation of the transmitted signals through the channel;
• measuring the system response to each of said test excitation signals and storing the system response data for each test excitation signal;
• transforming said stored system response data for each test excitation signal into the time domain, said transformed data indicating the relative time shift introduced by said time shift channels.

A wide band microwave array antenna system operating over a wide frequency band, comprising:

• a plurality of true-time-delay (TTD) time shifters in a plurality of time shift channels, each channel having a channel output port;
• a transmit feed network comprising an input port and a plurality of output ports for dividing a transmit excitation signal among said plurality of network output ports to distribute said signal among said time shift channels;
• and
• a signal collection network for collecting a portion of said excitation signals which have passed through said time shift channels, said collection network comprising a plurality of signal coupling devices for coupling off a portion of said excitation signals at each said channel output port, and a plurality of transmission lines connected in series with said respective coupling devices to provide said portion of said excitation signals at a collection port.

A wide band microwave array antenna system operating over a wide frequency band, comprising:

• a plurality of true-time-delay (TTD) time shifters in a plurality of time shift channels, each channel having a channel input port and a channel output port;
• a receive network comprising a plurality of input ports and an output port for combining signals received at said channel outputs into a combined signal at said device output port;
• and
• a test signal distribution network for distributing a portion of test excitation signals injected at a distribution input port among said plurality of input ports for said time shift channels, said distribution network comprising a plurality of signal coupling devices for coupling off a portion of said excitation signals at each said channel output port, and a plurality of transmission lines connected in series with said respective coupling devices.

A method for testing a wide band microwave array antenna system operating over a frequency band, the array system comprising a true-time-delay (TTD) beamforming network, comprising:

• transmitting a large number of test excitation signals at frequencies covering said frequency band within a short period of time through said array antenna system, to thereby synthesize a very short test excitation pulse;
• receiving said test excitation signals at a far field location of said system and retransmitting a time delayed version of said received signals back to said antenna system;
• using said antenna system in a receive configuration to receive said delayed version of said received signals;
• measuring the antenna system response to said delayed version of said transmitted test excitation signals and storing the system response data for each such signal;
• transforming said stored system response data into the time domain for analysis of a round trip performance characteristic of said antenna system.