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We present the co-fabrication of planar Gunn diodes and high electron mobility transistors (HEMTs) on an Indium Phosphide (InP) substrate for the first time. Electron beam lithography (EBL) has been used extensively for the complete fabrication procedure and a 70 nm T-gate technology was incorporated for the enhancement of the small-signal characteristics of the HEMT. Diodes with anode-to-cathode separation (Lac) down to 1 μm and 120 μm width where shown to oscillate up to 204 GHz. The transistor presents a cut-off frequency (fT) of 220 GHz, with power gain up to 330 GHz (fmax). The integration of the two devices creates the potential for the realisation of high-power, high-frequency MMIC Gunn oscillators, circuits and systems.

In this article, the resonant frequency and quality factor of a novel coplanar waveguide (cpw) diamond-shaped resonator were analyzed using advanced design system-2009 momentum model software. The diamond resonator was compared with the cpw radial stub resonator on gallium arsenide (GaAs); the work indicated that the diamond resonator had a smaller physical size and higher quality factor (Q) at millimetric wave frequencies. Experimentally measured diamond cpw resonators fabricated on GaAs were in good agreement with the simulated results.

In this paper, a very wide-band Yagi antenna suitable for high-data rate communication in the millimetre-wave frequency range is presented. The coplanar waveguide (CPW) fed antenna is realised on InP substrate using the CPW ground planes as the reflector elements. The measured S11 return loss under -10 dB shows a 100% bandwidth for the 140-220 GHz frequency band antenna and 50% for the 220-325 GHz frequency band antenna. The maximum measured gain of the antenna is 7.35 dB at 202 GHz and 4.75 dB at 260 GHz.

A series of resonant tunneling diode oscillators with frequencies up to W-band and output power around one milliwatt are presented. To our knowledge, the 75.2 GHz RTD oscillator with -0.2 dBm output power is the highest power reported. The technique demonstrated here shows the great potential to scale up the design to terahertz frequencies.\ud \ud Jue Wang, Khalid Alharbi, Afesomeh Ofiare, Ata Khalid, Liquan Wang, David Cumming and Edward Wasige

The demand for higher frequency applications is growing and a solid-state source for THz frequencies is needed. We compare experimentally demonstarted results of resonant tunneling diode and planar Gunn diodes for terahertz technology. The\ud highest power demonstrated for W-band RTD oscillators at 75.2 GHz with -0.2 dBm (0.96 mW) and at 300GHz for submicron planar Gunn with -16dBm (28μW) are compared as the potential solid-state source for Terahertz applications.

A new technique is demonstrated for the realisation of air bridges using one lithographic step. Gray scale lithography is used for the formation of 3D profiles on polymethyl methacrylate (PMMA) where a variable dose exposure is applied to create a trapezoid profile for the air bridge. In previous 3D electron beam lithography (EBL) methods the span area was exposed to a low dose or a low acceleration voltage [1,2,3]. Thus, the required discontinuity with the surrounding area for the lift-off process was created. In this technique, no exposure of the span area is needed. Another exposure of a gradient dose is applied to the sides of the highest part of the air bridge. The created profile, after developing the resist, is depicted in Figure 1. The surfaces with red and blue colour represent the metal to form the air bridge and the metal to lift-off, respectively. Using this configuration, the deposited metal at the sides of the top part of the air bridge is connected to the surrounding metal to lift-off and disconnect from the air bridge. The electron dose used in this area has to be smaller than the minimum dose that penetrates the total resist layer, so that the deposited metal does not reach the substrate. This method takes maximum advantage of the resist thickness for the fabrication of high structures, as no part of the resist is sacrificed

Stern flaps are appendages attached to the transom of a vessel which can decrease resistance at some speeds. This can translate to significant fuel savings when applied to a fleet of similar ships. A recent study investigating a stern flap design for the Canadian Navy's HALIFAX Class frigates showed a significant sensitivity to trim angle at high speeds. Further exploration on the role of trim angle was conducted using CFD simulations for three naval combatants: the Canadian HALIFAX Class, the U.S. CG-47/DD-963, and the U.S. DDG-51. The CFD simulations were validated against model test data for each hull type, and then used to determine the role of trim angle in resistance reduction from stern flaps., 27th Symposium on Naval Hydrodynamics, 5-10 October 2008, Seoul, Korea