Colin Viegas

A 40 to 160 GHz high power multiplier chain using planar Schottky diodes

This paper presents the design and performance of a x2x2 frequency multiplier chain from 40 to 160 GHz. The input power at 40 GHz is 500 mW with a final output power of 35 mW at 158 GHz. The 3 dB bandwidth at the output frequency is over 10%. The results demonstrate good agreement between the modeled and measured data. The work described in this paper involved extensive thermal modelling of the structure including the diode and filter circuits; this analysis allows good power handling performance for high power applications.

Millimeter wave radiometers for applications in imaging and nondestructive testing

This paper describes the development and characterisation of broadband radiometers centered at 94 and 183 GHz for passive millimeter wave imaging and NDT applications. The W-band radiometer has been built and tested using both fundamental and sub-harmonic mixer configurations. The 183 GHz radiometer uses a sub-harmonic mixer at the front-end and has an LO that is common with the fundamentally pumped W-band receiver. In this case the LO is supplied via a ~30 GHz source which is frequency tripled to 90 GHz with a conversion efficiency of around 10 %. The IF bandwidth for both fundamental and sub-harmonic W-band mixers is about 18 GHz while the 183 GHz mixer is 12 GHz. The room temperature DSB mixer noise temperature was measured to be around 500 K with a conversion loss of approximately 5 dB for 94 GHz and 183 GHz channels. NETD results for these radiometers are also presented.

Active Millimeter-Wave Radiometry for Nondestructive Testing/Evaluation of Composites—Glass Fiber Reinforced Polymer

Manufacture and in-service assessment of composite materials can be challenging since there is, yet, no standard method for testing them. Nevertheless, regular inspection is necessary to maintain the structural integrity. This paper describes a nondestructive, broadband noise mapping method that uses a millimeter-wave radiometer to detect defects in composite materials. The

Broadband THz imaging of composite materials

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Thermal analysis of high-power millimeter-wave Schottky diode frequency multipliers

-band system is configured for transmission mode measurement in which an amplified photonic source illuminates a glass fiber reinforced polymer containing machined defects. A high sensitivity radiometer is used for imaging the sample. The radiometer consists of a Schottky diode-based frequency tripler and a fundamental mixer.

High sensitivity broadband 360GHz passive receiver for TeraSCREEN

Imaging composite materials is a challenging task due to the continual improvement in material quality and inspection demands. This paper describes a novel broadband THz noise mapping technique that performs active imaging of composite materials. The transmission measurement consists of an amplified photonic noise source to illuminate the sample and a W-band Schottky diode based radiometer to obtain the intensity profile as a function of scan position. The experimental set-up and preliminary results are presented.

High sensitivity broadband 360 GHz front-end receiver for TeraSCREEN

This work presents the thermal analysis of a Schottky diode frequency doubler capable of providing over 30 mW at 160 GHz at room temperature. This analysis includes thermal modeling of its structure and characterization at different temperature conditions. The modeling of different Schottky diode multiplier chip layouts indicates that the analyzed circuit uses the optimum configuration from the thermal point of view. Finally, the performance predicted by a physics-based numerical electro-thermal model for Schottky diodes integrated into a circuit simulator based on the harmonic balance technique is also presented and compared with measured data on the 160 GHz frequency doubler.

A 332GHz frequency doubler using flip-chip mounted planar schottky diodes

TeraSCREEN is an EU FP7 Security project aimed at developing a combined active, with frequency channel centered at 360 GHz, and passive, with frequency channels centered at 94, 220 and 360 GHz, imaging system for border controls in airport and commercial ferry ports. The system will include automatic threat detection and classification and has been designed with a strong focus on the ethical, legal and practical aspects of operating in these environments and with the potential threats in mind. Furthermore, both the passive and active systems are based on array receivers with the active system consisting of a 16 element MIMO FMCW radar centered at 360 GHz with a bandwidth of 30 GHz utilizing a custom made direct digital synthesizer. The 16 element passive receiver system at 360 GHz uses commercial Gunn diode oscillators at 90 GHz followed by custom made 90 to 180 GHz frequency doublers supplying the local oscillator for 360 GHz sub-harmonic mixers. This paper describes the development of the passive antenna module, local oscillator chain, frequency mixers and detectors used in the passive receiver array of this system. The complete passive receiver chain is characterized in this paper.

Characterization of 94 GHz and 183 GHz planar schottky diode based radiometer modules

The development is described of a 360 GHz sub-harmonic mixer for the active and passive sub-systems of the TeraSCREEN security scanner by STFC RAL Space. The mixers operate as predicted with state-of-the-art performance. A radiometer sensitivity measurement also shows the devices have outstanding performance.

A 180-GHz Schottky Diode Frequency Doubler With Counter-Rotated

A 166/332GHz frequency doubler based on a Schottky diode has been designed and measured. It uses a diode chip with two Schottky varactor diodes in a balanced configuration, flip-chip mounted to a 50um thick quartz filter substrate. The doubler uses a fixed tune split waveguide block designed for ease of assembly. Measurements show a peak efficiency around 4.7% at 332.8GHz, with 1.2 mW output power at room temperature.