Abstract: Systems and methods for calibrating and optimizing frequency modulated continuous wave radar altimeters using adjustable self-interference cancellation are disclosed. In at least one embodiment, a radar altimeter system comprises: a local oscillator delay line including a variable delay circuit configured to output a delayed signal, a transmitter coupled to the local oscillator delay line and configured to output a transmitter signal, a transceiver circulator coupled to an antenna and coupled to the transmitter, and a frequency mixer coupled to the delay line and coupled to the transceiver circulator. The transceiver circulator directs the transmitter signal to the antenna and the antenna is configured to transmit the transmitter signal and receive a reflected signal from a target. Further, the frequency mixer is configured to receive the delayed signal and the target reflected signal from the transceiver circulator.

Abstract: Systems and methods for a variable delay line using variable capacitors in a time delay filter are provided. In at least one embodiment, a delay line is configured to apply an adjustable time delay to an electromagnetic signal travelling through the delay line. The delay line comprises a filter that includes a first variable capacitor. Further, a capacitance of the first variable capacitor is configured to adjust the delay applied to the electromagnetic signal travelling through the delay line when varied.

Abstract: An altimeter system is provided. The altimeter system includes a receiver mixer including an antenna-input and a local-oscillator-input; a transceiver circulator communicatively coupled to an antenna via a transmission line having a selected length and communicatively coupled to the antenna-input of the receiver mixer; and a transmitter configured to output a transmitter signal to the antenna via the transceiver circulator. The transmitter signal is frequency modulated with a linear ramp. The transmitter is communicatively coupled to the receiver mixer to input a local oscillator signal at the local-oscillator-input of the receiver mixer. The receiver mixer is communicatively coupled to input a target-reflected signal from the antenna at the antenna-input of the receiver mixer. The selected length of the transmission line is set so that a composite-leakage signal at the antenna-input of the receiver mixer has a linear phase across a sweep bandwidth.

Abstract: An altimeter system is provided. The altimeter system includes a receiver mixer including an antenna-input and a local-oscillator-input; a transceiver circulator communicatively coupled to an antenna via a transmission line having a selected length and communicatively coupled to the antenna-input of the receiver mixer; and a transmitter configured to output a transmitter signal to the antenna via the transceiver circulator. The transmitter signal is frequency modulated with a linear ramp. The transmitter is communicatively coupled to the receiver mixer to input a local oscillator signal at the local-oscillator-input of the receiver mixer. The receiver mixer is communicatively coupled to input a target-reflected signal from the antenna at the antenna-input of the receiver mixer. The selected length of the transmission line is set so that a composite-leakage signal at the antenna-input of the receiver mixer has a linear phase across a sweep bandwidth.

Abstract: An altimeter system is provided. The altimeter system includes a receiver mixer including an antenna-input and a local-oscillator-input; a transceiver circulator communicatively coupled to an antenna via a transmission line having a selected length and communicatively coupled to the antenna-input of the receiver mixer; and a transmitter configured to output a transmitter signal to the antenna via the transceiver circulator. The transmitter signal is frequency modulated with a linear ramp. The transmitter is communicatively coupled to the receiver mixer to input a local oscillator signal at the local-oscillator-input of the receiver mixer. The receiver mixer is communicatively coupled to input a target-reflected signal from the antenna at the antenna-input of the receiver mixer. The selected length of the transmission line is set so that a composite-leakage signal at the antenna-input of the receiver mixer has a linear phase across a sweep bandwidth.

Abstract: An altimeter system is provided. The altimeter system includes a receiver mixer including an antenna-input and a local-oscillator-input; a transceiver circulator communicatively coupled to an antenna via a transmission line having a selected length and communicatively coupled to the antenna-input of the receiver mixer; and a transmitter configured to output a transmitter signal to the antenna via the transceiver circulator. The transmitter signal is frequency modulated with a linear ramp. The transmitter is communicatively coupled to the receiver mixer to input a local oscillator signal at the local-oscillator-input of the receiver mixer. The receiver mixer is communicatively coupled to input a target-reflected signal from the antenna at the antenna-input of the receiver mixer. The selected length of the transmission line is set so that a composite-leakage signal at the antenna-input of the receiver mixer has a linear phase across a sweep bandwidth.

Abstract: Systems and methods for calibrating and optimizing frequency modulated continuous wave radar altimeters using adjustable self-interference cancellation are disclosed. In at least one embodiment, a radar altimeter system comprises: a local oscillator delay line including a variable delay circuit configured to output a delayed signal, a transmitter coupled to the local oscillator delay line and configured to output a transmitter signal, a transceiver circulator coupled to an antenna and coupled to the transmitter, and a frequency mixer coupled to the delay line and coupled to the transceiver circulator. The transceiver circulator directs the transmitter signal to the antenna and the antenna is configured to transmit the transmitter signal and receive a reflected signal from a target. Further, the frequency mixer is configured to receive the delayed signal and the target reflected signal from the transceiver circulator.

Abstract: Systems and methods for a variable delay line using variable capacitors in a time delay filter are provided. In at least one embodiment, a delay line is configured to apply an adjustable time delay to an electromagnetic signal travelling through the delay line. The delay line comprises a filter that includes a first variable capacitor. Further, a capacitance of the first variable capacitor is configured to adjust the delay applied to the electromagnetic signal travelling through the delay line when varied.

Abstract: An altimeter system is provided. The altimeter system includes a receiver mixer including an antenna-input and a local-oscillator-input; a transceiver circulator communicatively coupled to an antenna via a transmission line having a selected length and communicatively coupled to the antenna-input of the receiver mixer; and a transmitter configured to output a transmitter signal to the antenna via the transceiver circulator. The transmitter signal is frequency modulated with a linear ramp. The transmitter is communicatively coupled to the receiver mixer to input a local oscillator signal at the local-oscillator-input of the receiver mixer. The receiver mixer is communicatively coupled to input a target-reflected signal from the antenna at the antenna-input of the receiver mixer. The selected length of the transmission line is set so that a composite-leakage signal at the antenna-input of the receiver mixer has a linear phase across a sweep bandwidth.