Abstract: An outphasing antenna structure is provided that includes a first antenna feeder and a second antenna feeder. A high-PAPR signal is decomposed into a first constant-envelope signal that drives the first antenna feeder and into a second constant-envelope signal that drives the second antenna feeder. The pair of antenna feeders parasitically couple to an antenna that radiates the first and second constant-envelope signals that spatially combine in free space into the high-PAPR signal.

Abstract: Disclosed is a method of encrypting a data signal for providing to an input of a radio frequency transmitter, such as modulated baseband signals in the physical layer for wireless transmission. The method comprises receiving the data signal comprising one or more first frequency components with a first phase profile in a frequency band of interest; applying a dispersive encrypting signal filter to the data signal to generate an encrypted data signal comprising the one or more frequency components with a second phase profile, wherein the second phase profile is different to the first phase profile. Decryption is achieved by applying a decrypting filter to the encrypted data signal to substantially reverse the effect of the encrypting filter and recover the first phase profile.

Abstract: A method for determining amplitude and phase correction coefficients for one or more signal processing paths across a frequency band of interest is provided. The method comprises transforming an input test signal from the time domain to the frequency domain to obtain an input magnitude spectrum and an input phase spectrum for the/each signal processing path. It further comprises transforming an/each respective output test signal from the time domain to the frequency domain to obtain an output magnitude spectrum and an output phase spectrum for the/each signal processing path. It also comprises comparing the/each input magnitude spectrum with its respective output magnitude spectrum to determine an amplitude correction coefficient for the/each signal processing path and/or comparing the/each input phase spectrum with its respective output phase spectrum, to determine a phase correction coefficient for the or each signal processing path.

Abstract: Disclosed is a method of encrypting a data signal for providing to an input of a radio frequency transmitter, such as modulated baseband signals in the physical layer for wireless transmission. The method comprises receiving the data signal comprising one or more first frequency components with a first phase profile in a frequency band of interest; applying a dispersive encrypting signal filter to the data signal to generate an encrypted data signal comprising the one or more frequency components with a second phase profile, wherein the second phase profile is different to the first phase profile. Decryption is achieved by applying a decrypting filter to the encrypted data signal to substantially reverse the effect of the encrypting filter and recover the first phase profile.

Abstract: Disclosed is a method of encrypting a data signal for providing to an input of a radio frequency transmitter, such as modulated baseband signals in the physical layer for wireless transmission. The method comprises receiving the data signal comprising one or more first frequency components with a first phase profile in a frequency band of interest; applying a dispersive encrypting signal filter to the data signal to generate an encrypted data signal comprising the one or more frequency components with a second phase profile, wherein the second phase profile is different to the first phase profile. Decryption is achieved by applying a decrypting filter to the encrypted data signal to substantially reverse the effect of the encrypting filter and recover the first phase profile.

Abstract: A method for determining amplitude and phase correction coefficients for one or more signal processing paths across a frequency band of interest is provided. The method comprises transforming an input test signal from the time domain to the frequency domain to obtain an input magnitude spectrum and an input phase spectrum for the/each signal processing path. It further comprises transforming an/each respective output test signal from the time domain to the frequency domain to obtain an output magnitude spectrum and an output phase spectrum for the/each signal processing path. It also comprises comparing the/each input magnitude spectrum with its respective output magnitude spectrum to determine an amplitude correction coefficient for the/each signal processing path and/or comparing the/each input phase spectrum with its respective output phase spectrum, to determine a phase correction coefficient for the or each signal processing path.

Abstract: In one embodiment, an apparatus for automatically testing and tuning a RF coil is provided. The apparatus comprises a digital frequency generator for generating a stimulus, the stimulus comprising a range of radio frequency signals having different frequencies, a radio frequency coupler configured for applying the stimulus to the RF coil so as to enable the RF coil to generate a reflected signal in response to the stimulus applied, a radio frequency detector for detecting the reflected signal and a signal processing unit for processing the reflected signal, so as to identify the tuned resonant frequency of the RF coil and further configured for calculating return loss at the RF coil based on the reflected signal.

Abstract: In one embodiment, an apparatus for automatically testing and tuning a RF coil is provided. The apparatus comprises a digital frequency generator for generating a stimulus, the stimulus comprising a range of radio frequency signals having different frequencies, a radio frequency coupler configured for applying the stimulus to the RF coil so as to enable the RF coil to generate a reflected signal in response to the stimulus applied, a radio frequency detector for detecting the reflected signal and a signal processing unit for processing the reflected signal, so as to identify the tuned resonant frequency of the RF coil and further configured for calculating return loss at the RF coil based on the reflected signal.

Abstract: In one embodiment a radio frequency receiver for a magnetic resonance imaging system is provided. The radio frequency receiver comprises a RF coil for receiving one or more radio frequency signals transmitted through an object to be imaged so as to enable a reconstruction processor to generate an image representation of the object based on the received radio frequency signals, a local oscillator configured for generating a stimulus, the stimulus comprising a range of radio frequency signals having different frequencies and a flux probe coupled to the local oscillator, the flux probe configured for applying the stimulus to the RF coil. Further, the RF coil is configured for returning a reflected signal in response to the stimulus applied and comprises at least one digitally tunable capacitor.