US 5,051,754 A · Optoelectronic wide bandwidth photonic beamsteering phased array

Abstract

A transmit/receive circuit for each of the antenna elements of a radar phased array including an optical fiber true time delay circuit responsive to an electrical RF signal for providing an optical signal having a controlled time delay, an optical fiber for propagating the time delay controlled optical signal, an optical detector circuit responsive to the propagated time delay controlled optical signal for providing a time delay controlled electrical signal, transmit circuitry responsive to the time delay controlled electrical signal for providing to the associated antenna element a transmit signal based on the time delay controlled electrical signal, and receive circuitry responsive to the time delay controlled electrical signal and the signal received by the associated antenna element. A first RF switch selectively couples the time delay controlled electrical signal to the transmit circuit during transmit times, and to the receive circuit during receive times; and a second RF switch couples the associated antenna element to the transmit circuit during transmit times, and to the receive circuit during receive times. The receive circuit further includes analog-to-digital conversion circuitry whose sample timing is controlled so as to provide for the time alignment of the received signal relative to the received signals of the other transmit/receive circuits of the phased array. Alternatively, such time alignment is provided pursuant to processing of the sampled receive signals from the transmit/receive circuits of the phased array.

Claims10

Dependent claims

In a phased array radar system having a radar processor and a plurality of antenna elements, a transmit/receive circuit for each of the antenna elements comprising:

an optical fiber true time delay circuit responsive to an electrical RF signal for providing an optical signal having a controlled time delay relative to the outputs of the optical fiber true time delay circuits of the other transmit/receive circuits in the array;
optical means for propagating said true time delay controlled optical signal;
optical detection means responsive to the propagated true time delay controlled optical signal for providing a true time delay controlled electrical signal;
transmit means responsive to said true time delay controlled electrical signal for providing a transmit signal based on said true time delay controlled electrical signal to the associated antenna element;
receive means responsive to said true time delay controlled electrical signal and the signal received by the associated antenna element for providing a baseband received signal, said true time delay controlled electrical signal being utilized as the local oscillator signal to provide the correct phase for steering the array;
true time delay processing means responsive to said baseband received signal for providing a digital received signal that is properly aligned relative to the digital received signals provided by the receive means of the other transmit/receive circuits of the array;
first switching means for coupling said true time delay controlled electrical signal to said transmit means during transmit times, and to said receive means during receive times;
and
second switching means for coupling the associated antenna element to said transmit means during transmit times, and to said receive means during receive times.

6 more elements

In a phased array radar system having a radar processor and a plurality of antenna elements, a transmit/receive circuit for each of the antenna elements comprising:

an optical fiber true time delay circuit responsive to an electrical RF signal for providing an optical signal having a controlled time delay relative to the outputs of the optical fiber true time delay circuits of the other transmit/receive circuits in the array;
optical means for propagating said true time delay controlled optical signal;
optical detection means responsive to the propagated true time delay controlled optical signal for providing a true time delay controlled electrical signal;
transmit means responsive to said true time delay controlled electrical signal for providing a transmit signal based on said true time delay controlled electrical signal to the associated antenna element;
receive means responsive to said true time delay controlled electrical signal and the signal received by the associated antenna element for providing a baseband received signal, said true time delay controlled electrical signal being utilized as the local oscillator signal to provide the correct phase for steering the array;
analog to digital conversion means responsive to said baseband received signal for providing a digital received signal;
optical means responsive to digital received signal for providing an optical received signal to the radar processor;
first switching means for coupling said true time delay controlled electrical signal to said transmit means during transmit times, and to said receive means during receive times;
and
second switching means for coupling the associated antenna element to said transmit means during transmit times, and to said receive means during receive times.

7 more elements

Dependencies are inferred from the claim text.

Optoelectronic wide bandwidth photonic beamsteering phased array

Life of this patent

Optoelectronic wide bandwidth photonic beamsteering phased array

Life of this patent

Abstract

Claims10