Samuel Ver Hoeye

Design and analysis of a microwave large-range variable phase-shifter based on an injection-locked harmonic self-oscillating mixer

In this letter, a new microwave variable phase-shifter based on an injection-locked harmonic self-oscillating mixer, is presented for its application in an active microstrip phased antenna array. The circuit provides the double functionality of variable phase-shifter and down-converter. Maximum conversion gain is obtained, through the optimization of a new multi-harmonic load at the input-port of the circuit. The ranges of synchronized operation are analyzed versus the circuit parameters and the corresponding phase-shifts are calculated. The stability of the synchronized solutions is analyzed using the envelope transient simulation method. An 11.25-1.5-GHz down-converter with a 3.25-GHz free-running frequency has been designed, providing a phase-shift variation at intermediate frequency up to 540/spl deg/, with a 4.5-dB conversion gain. A good agreement between the simulated and experimental results has been found.

Defected Ground Structure for Coupling Reduction between Probe Fed Microstrip Antenna Elements

The mutual coupling between elements of a microstrip antenna design based on stacked patches has been studied in an array conflguration. In order to mitigate the mutual coupling, a defected ground structure based on narrow, closely spaced rectangular slots has been proposed. Two arrangements with three and flve slots have been studied and optimised in an array conflguration with 0:7‚0 element separation. For the experimental validation of the simulated results, prototypes of two element antenna arrays with both DGS designs, as well as without DGS, have been manufactured and measured.

Receiving Phased Antenna Array Based on Injection-Locked Harmonic Self-Oscillating Mixers

A 4 times 1 element receiving phased antenna array is presented with phase-shifter elements based on injection-locked harmonic self-oscillating mixers. Each phase-shifter element provides the double functionality of variable phase-shifter and down-converter. The phase-shifts applied to the input signals coming from the different antenna patch elements can be selected by dc control signals in a continuous range of 450deg. The required dc control voltages are calculated for the different incident angles by means of harmonic balance simulations. The influences of phase-shift and conversion gain errors on the beam-steering frequency performance of the antenna are studied. Also illustrated is how the phase-shifter parameters can be optimized in order to minimize the frequency scanning. A 4 times 1 element receiving phased antenna array, with an input frequency band centered at 11.25 GHz and the output frequency band centered at 1.5 GHz, has been manufactured for the experimental validation of the simulated results. A beam scanning range from -23deg to 23deg has been experimentally obtained.

High-Order Subharmonic Millimeter-Wave Mixer Based on Few-Layer Graphene

A millimeter-wave subharmonic-mixer topology based on a few-layer graphene component has been designed, manufactured, and experimentally characterized. The circuit has been conceived to perform the up/downconversion of a signal in the WR-3 band, between 220-330 GHz, using a high-order harmonic component of the input signal in the WR-28 band, between 26.5-40 GHz, as a local oscillator. The manufactured prototype has been characterized in both upconversion and downconversion, for the subharmonic orders between 5-14, obtaining a peak conversion gain value over -65 dB. The theoretically predicted capability of graphene to produce high-order intermodulation products at millimeter-wave frequencies, with a slowly decaying amplitude pattern, has been experimentally verified.

Analysis of the Locking Range of Rationally Synchronized Oscillators With High Reference Signal Power

In this paper an in-depth study of the behavior of rationally synchronized oscillators (RSO) is presented. The circuit is optimized in order to achieve a broad synchronization bandwidth with low reference signal power through the selection of the adequate harmonic content. The nonlinear dynamics of the RSO is analyzed, focusing on the different bifurcation points which delimit the locking range when high reference signal power is considered. An RSO prototype with rational synchronization ratio r=3/5, autonomous frequency fo=3 GHz and reference signal frequency fr=5 GHz has been manufactured and experimentally characterized, demonstrating a good agreement with simulation results.

Millimetre wave imaging system for the detection of hidden elements in artwork

In this work, a millimetre/sub-millimetre wave imaging system for the analysis, characterisation and detection of hidden elements in artwork is presented. The practical implementation of the system relies on a novel generation of purpose developed frequency multiplier and mixer topologies, based on graphene non-linear devices. The proposed set-up will be experimentally validated by scanning a model painting, in order to practically illustrate the imaging capabilities of the system.

Submillimeter Wavelength 2-D Frequency Scanning Antenna Based on Slotted Waveguides Fed Through a Phase Shifting Network

This paper describes a 2-D frequency scanning array, operating in the 240–310-GHz frequency range, which is intended to be used in electromagnetic imaging applications. The proposed antenna combines eight slotted waveguides that are parallel fed through a frequency-dependent phase shifting network. As the working frequency is swept in the considered range, the inherent frequency-dependent behavior of the slotted waveguide causes beam scanning in one plane, while the progressive phase shift introduced by the feeding network provides beam steering in the perpendicular direction. The influence of the particular negative effects that suffer the employed structures on the array performance is carefully analyzed to determine the viability of this approach. A prototype has been implemented and experimentally characterized. The manufactured antenna presents a measured 20-dBi minimum gain and it is able to scan a

3D printed millimeter wave receiver integrating a graphene subharmonic mixer and a diagonal horn antenna

60 {^{\circ }}\times 20 {^{\circ }}

Millimetre wave receiver based on a few-layer graphene WR-5 band subharmonic mixer

space region, which would be large enough for a great number of imaging applications.

7 th order sub-millimeter wave frequency multiplier based on graphene implemented using a microstrip transition between two rectangular waveguides

This work presents a millimeter/submillimeter wave frequency receiver integrating a graphene subharmonic mixer and a diagonal horn antenna. The device receives the RF signal through the diagonal horn antenna directly connected to the WR-3 input of the mixer. The desired frequency mixing performance is obtained using the non-linear behavior of a few-layer graphene film placed on a microstrip line gap. Using the internally generated 6th, 8th and 10th harmonic components of the input signal provided by the WR-28 standard waveguide in the 26-40 GHz the downconversion operation of the RF signal to a 300 MHz intermediate frequency is performed. A prototype of the receiver has been manufactured using high precision 3D printing technology. The performance of this device is characterized taking into account the behavior of the IF power in the 220-330 GHz band. Measured radiation patterns are also included.