In an embodiment, a method for determining the phase shift between a first signal and a second signal includes: delivering the first signal to a first input of a 90° hybrid coupler; delivering the second signal to a second input of the 90° hybrid coupler; determining a first piece of information relating to a power of a first output signal delivered to a first output of the 90° hybrid coupler; determining a second piece of information relating to a power of a second output signal delivered to a second output of the coupler; and adjusting the phase of the second signal until obtaining a calibrated phase for which the first piece of information is substantially equal to the second piece of information, wherein the first and second signals have identical frequencies, and wherein the phase shift between the first signal and the second signal is equal to the calibrated phase.

A system for passive microwave remote sensing using at least one microwave radiometer includes a fixed body portion and a mobile body portion. The mobile body portion is configured for rotatably coupling with the fixed body portion for rotation about a rotation axis. The mobile body portion is configured for supporting the microwave radiometer therein such that the microwave radiometer rotates about the rotation axis when the mobile body portion is rotated about the rotation axis such that a polarization axis of the radiometer is aligned with an earth axis. The fixed body portion includes a motor mechanism for effecting rotation of the mobile body portion. In an embodiment, the mobile body portion includes a plurality of body section, each body section being configured for supporting a microwave radiometer therein. In another embodiment, each one of the plurality of body sections is configured to be interchangeably coupled with each other.

The method for detecting the phase (Φ1) of an analog signal (SA1) via a hybrid coupler (CH1) operating in a power-combiner mode, the hybrid coupler (CH1) comprising a first input (BE1) intended to receive the analog signal (SA1), a second input (BE2) intended to receive a reference signal (SREF) having a reference phase (Φ2) and the same frequency (FREF) as the analog signal (SA1), and two outputs (BS1, BS2), and configured to generate, at these two outputs (BS1, BS2), a first output signal (SS1) and a second output signal (SS2), respectively, comprises measuring peak values (A1, A2, A3, A4) of the analog signal (SA1), of the reference signal (SREF), and of at least one of the first and second output signals (SS1, SS2), calculating the phase shift (Φ1-Φ2) between the phase (Φ1) of the analog signal and the reference phase (Φ2) depending on said measured peak values (A1, A2, A3, A4), and determining the phase (Φ1) of the analog signal (SA1) depending on said calculated phase shift (Φ1-Φ2) and the reference phase (Φ2).

The method for detecting the phase (Φ1) of an analog signal (SA1) via a hybrid coupler (CH1) operating in a power-combiner mode, the hybrid coupler (CH1) comprising a first input (BE1) intended to receive the analog signal (SA1), a second input (BE2) intended to receive a reference signal (SREF) having a reference phase (Φ2) and the same frequency (FREF) as the analog signal (SA1), and two outputs (BS1, BS2), and configured to generate, at these two outputs (BS1, BS2), a first output signal (SS1) and a second output signal (SS2), respectively, comprises measuring peak values (A1, A2, A3, A4) of the analog signal (SA1), of the reference signal (SREF), and of at least one of the first and second output signals (SS1, SS2), calculating the phase shift (Φ1-Φ2) between the phase (Φ1) of the analog signal and the reference phase (Φ2) depending on said measured peak values (A1, A2, A3, A4), and determining the phase (Φ1) of the analog signal (SA1) depending on said calculated phase shift (Φ1-Φ2) and the reference phase (Φ2).

In an embodiment, a method for determining the phase shift between a first signal and a second signal includes: delivering the first signal to a first input of a 90° hybrid coupler; delivering the second signal to a second input of the 90° hybrid coupler; determining a first piece of information relating to a power of a first output signal delivered to a first output of the 90° hybrid coupler; determining a second piece of information relating to a power of a second output signal delivered to a second output of the coupler; and adjusting the phase of the second signal until obtaining a calibrated phase for which the first piece of information is substantially equal to the second piece of information, wherein the first and second signals have identical frequencies, and wherein the phase shift between the first signal and the second signal is equal to the calibrated phase.

In certain aspects, an apparatus includes a power detector coupled between a power amplifier and an antenna, and a voltage detector coupled between the power amplifier and the antenna. The apparatus also includes a phase shifter coupled to the power detector, and a load measurement circuit coupled to the power detector, the voltage detector, and the phase shifter.

In certain aspects, an apparatus includes a power detector coupled between a power amplifier and an antenna, and a voltage detector coupled between the power amplifier and the antenna. The apparatus also includes a phase shifter coupled to the power detector, and a load measurement circuit coupled to the power detector, the voltage detector, and the phase shifter.

A circuit includes a radio frequency (RF) channel including an input node and an output node and being configured to receive an RF oscillator signal at the input node and to provide an RF output signal at the output node; a mixer configured to mix an RF reference signal and an RF test signal representative of the RF output signal to generate a mixer output signal; an analog-to-digital converter configured to sample the mixer output signal in order to provide a sequence of sampled values; and a control circuit configured to provide a sequence of phase offsets by phase-shifting at least one of the RF test signal and the RF reference signal using one or more phase shifters, calculate a spectral value from the sequence of sampled values; and calculate estimated phase information indicating a phase of the RF output signal based on the spectral value.

A circuit includes a radio frequency (RF) channel including an input node and an output node and being configured to receive an RF oscillator signal at the input node and to provide an RF output signal at the output node; a mixer configured to mix an RF reference signal and an RF test signal representative of the RF output signal to generate a mixer output signal; an analog-to-digital converter configured to sample the mixer output signal in order to provide a sequence of sampled values; and a control circuit configured to provide a sequence of phase offsets by phase-shifting at least one of the RF test signal and the RF reference signal using one or more phase shifters, calculate a spectral value from the sequence of sampled values; and calculate estimated phase information indicating a phase of the RF output signal based on the spectral value.

A circuit is described herein. In accordance with one embodiment the circuit includes two or more RF channels, wherein each channel includes an input node, a phase shifter and an output node. Each channel is configured to receive an RF oscillator signal at the input node and to provide an RF output signal at the output node. The circuit further includes an RF combiner circuit that is coupled with the outputs of the RF channels and configured to generate a combined signal representing a combination of the RF output signals, and a monitor circuit that includes a mixer and is configured to receive and down-convert the combined signal using an RF reference signal. Thus a mixer output signal is generated that depends on the phases of the RF output signals.