In brief

Abstract

PAGE 423 Advances in miniaturised multiband directional dipole antennas (DDA) for mobile communication applications are put forward by a team from Korea. They added a flat reflector to improve directivity and inverted L-shape stubs to enhance front-directivity as well as reduce the antenna size. These developments meet the multiband demands of mobile communication and could lead to reduced antenna size. PAGE 468 A simple-to-implement, capacitive type TiN/plasma-enhanced chemical vapour deposition (PECVD)-Si3N4/TiN diaphragm-based MEMS acoustic sensor is proposed that could be used in communication technology such as mobile phones. Korean researchers found that, through planarisation, the proposed transducer was greatly improved. They also carried out capacitance and equivalent circuit modelling. Increasing use of mobile devices has been driving antenna development PAGE 432 A group from France have proposed a half-digital feedback system that can cancel unwanted signals at the input of a continuous-time analogue-to-digital converter (CT-ADC). The resulting activity-dependent power consumption and an easily tunable transfer function make it ideal for use in low-power radio back-ends. The sensor features a 56% lower air-gap resistance compared with non-planarised models PAGE 418 A team from China have proposed a new approach to designing an absorptive frequency selective surface (AFSS). It allows high frequency waves (∼10 GHz) to transmit with very low insertion loss (less than 0.15 dB) by using the resonance between a parallel microstrip LC structure. It has wideband absorptive properties over low band frequencies (3–9 GHz) and good transmissive properties at high frequency. This advance can be used in radome antenna systems as it will allow the absorption of out-of-band waves from radar. CT-ADCs do not create any aliases thus do not require an anti-aliasing filter PAGE 479 Researchers in Japan have produced a resonant tunnelling diode terahertz voltage-controlled oscillator (RTD VCO) with a wide tuning range of 320 GHz (580–900 GHz), the largest range for all modern semiconductor devices. There is the possibility of increasing this by upping the number of VCOs, which could extend the range of frequency tuning up to 1 THz. The advances presented can be used in terahertz spectroscopy. The parallel LC structure is optimised to resonate at 10 GHz The tuning range can be controlled by the length of the slot antenna and the areas of the RTD and varactor diode