Tunable bandstop MEMS filter for millimetre-wave applications

The design and realisation of original millimetre-wave tunable bandstop filters using MEMS (micro-electro-mechanical-systems) technology for millimetre-wave applications is presented. The tunable behaviour is achieved by using MEMS switches. The overall structures, including the MEMS switches, have been manufactured using dielectric membrane in order to minimise the dielectric losses. Experimental validations are reported and validate the proposed topology: the bandstop frequency is shifted by approximately 3.5 GHz in V-band when the switches are actuated     

Matching of active millimetre-wave slot-line antennas

The matching of a radiating, resonant structure to an active millimetre-wave device is investigated. As an active device, an IMPATT diode is considered to be matched to a planar slot-line structure. An analytical IMPATT diode model and an equivalent circuit of the slot line are used to calculate possible oscillation frequencies and large-signal modulation parameters of the diode. In the case of matching the output power is predicted. The results are in satisfactory agreement with experimental data and suggest a diode design with shorted drift regions and reduced diode area for optimum impedance matching.<>     

Selectivity-improved E-plane filter for millimetre-wave applications

Measurements on a Ka-band selectivity-improved E-plane filter prototype are compared with computed predictions and are found to be in excellent agreement. The measured insertion loss is 1.5 dB, and the bandwidth is 180 MHz centred at 32.8 GHz. These prototype measurements confirm that this design has the potential for significantly improving the performance of filter components in the millimetre-wave frequency range.<>     

Compact membrane-supported bandpass filter for millimetre-wave applications

The design and testing of a new configuration of micromachined bandpass filter for millimetre-wave applications is presented. The design is based on image parameter representation of identical symmetrical cells connected in cascade. The measurements demonstrate transmission losses lower than 1 dB and very good agreement with the electromagnetic simulations.     

Bow-tie antennas on high dielectric substrates for MMIC and OEICapplications at millimetre-wave frequencies

A two-element bow-tie dipole antenna and a single-element bow-tie slot antenna fabricated on a high dielectric constant (ε_r=10.2) substrate are introduced for applications at millimetre-wave frequencies. The former antenna provides 2 GHz bandwidth at 35 GHz and the latter 1.3 GHz at 32.7 GHz. With a broadband match, these antennas would yield significantly higher bandwidths     

Integrated circuit transmission-line transformer power combiner for millimetre-wave applications

A new approach for power combining several low-voltage CMOS amplifiers using a new on-chip transmission line transformer structure is presented. The power combiner utilises the interconnection of short sections of integrated differential lines and has an efficiency independent of the transformation ratio. Full-wave electromagnetic simulation confirms the operation and low insertion loss of the transformer     

CMOS IMPATT impedance and design parameters for millimetre-wave applications

This article describes lateral CMOS IMPATT diodes designed, monolithically integrated and fabricated in 0.18?µm CMOS technology. IMPATT diode impedance and avalanche frequency were confirmed in a measurement from 40?MHz to 110?GHz. Avalanche tuning range measured from 24?GHz to 44?GHz with maximum IMPATT negative resistance of 120?Ω at 38?GHz with 28?mA bias current. Furthermore, selection of the process technology and the impact of n-well impurity concentration are discussed. This device showed wide tuning range in the millimetre wave range and with the low cost of the CMOS technology used, these devices appear well suited for use in millimetre-wave applications.     

Microstrip antennas for SAR applications

This paper discusses various methods of implementing a shared-aperture dual-frequency dual-polarized array antenna for spaced-based synthetic aperture radar (SAR) applications. After evaluating the use of several potential array architecture concepts and radiating elements, a design using interlaced C-band microstrip patches and X-band printed slot elements was chosen as the best choice for the present system requirements. Layout considerations for the two arrays and their associated feed networks are addressed in terms of a practical design. A dual-frequency (C- and X-band), dual-linear polarized SAR array antenna prototype was designed, fabricated, and tested. The principal goal of this effort was to demonstrate the viability of the dual-band dual-polarized array concept, and this has been accomplished. Test results are shown with good correlation between measured and predicted results, validating the design approach used. This work demonstrates that a dual-frequency dual-polarization SAR antenna within a single aperture is a feasible approach to meeting user requirements in future SAR spacecraft     

Pulsed silicon double-drift IMPATTs for microwave and millimetre-wave applications

The letter describes silicon double-drift IMPATT diodes designed for operation at microwave and millimetre-wave frequencies. These devices have delivered pulsed-power outputs of 16 W with 12.3% efficiency in the X band, 11 W with 14% efficiency in the KU band, and 6.4 W with 5.3% efficiency in the Ka band. These results, when combined with the demonstrated high reliability of silicon IMPATTS, should lead to the wide application of double-drift devices in pulsed-radar systems.     

GaAs planar doped barrier diodes for millimetre-wave detector applications

Epitaxially grown GaAs planar doped barrier diodes have been designed and fabricated into coplanar structures specifically for millimetre-wave zero-bias detector applications. Results at 35 GHz and 94 GHz show that the tangential sensitivity, voltage sensitivity and dynamic range of these devices can significantly exceed those of any comparable Schottky diode detector. This is the first report of such a result.<>     

Multifunctional reconfigurable MEMS integrated antennas for adaptive MIMO systems

Multi-input multi-output systems with associated technologies such as smart antennas and adaptive coding and modulation techniques enhance channel capacity, diversity, and robustness of wireless communications as has been proven by many recent research results both in theory and experiments. This article focuses on the antenna aspect of MIMO systems. In particular, we emphasize the important role of the reconfigurable antenna and its links with space-time coding techniques that can be employed for further exploitation of the theoretical performance of MIMO wireless systems. The advantages of the reconfigurable antenna compared to the traditional smart antenna are discussed. Establishment of reconfigurable antennas requires novel radio frequency microelectromechanical systems technology, which has recently been developed in the authors' group. We briefly introduce this technology with emphasis on its distinct advantages over existing silicon-based MEMS technologies for reconfigurable antennas. A reconfigurable antenna design that can change its operating frequency and radiation/polarization characteristics is described. Finally, we present the experimental and theoretical results from impedance and radiation performance characterization for different antenna configurations.     

Broadband printed circularly-polarised aperture antenna array for millimetre-wave gigabit applications

A simple and successful design of a printed aperture antenna array is presented in view of high-speed millimetre-wave wireless access applications. The antenna element design is based on a broadband travelling- wave aperture antenna for circularly-polarised radiation. For the antenna array design, the sequential rotation scheme is employed for improving the co-polarised gain and axial ratio. The presented antenna array is designed in the 40?48 GHz band and implemented with a 5mil-thick RT/Duroid-5880 PCB. Promising performances are achieved, including a return loss (,10 dB) bandwidth of 32%, an axial ratio (,3 dB) bandwidth of 25%, and a co-polarised gain (flatness , 3 dB) bandwidth of 32% with a maximum gain of 11dBic.     

Integrated horn antennas for millimeter-wave applications

The development of integrated horn antennas since their introduction in 1987 is reviewed. The integrated horn is fabricated by suspending a dipole antenna, on a thin dielectric membrane, in a pyramidal cavity etched in silicon. Recent progress has resulted in optimized low- and high-gain designs, with single and double polarization for remote-sensing and communication applications. A full-wave analysis technique has resulted in an integrated antenna with performance comparable to that of waveguide-fed corrugated-horn antennas. The integrated horn design can be extended to large arrays, for imaging and phased-array applications, while leaving plenty of room for the RF and IF processing circuitry. Theoretical and experimental results at microwave frequencies and at 90 GHz, 240 GHz, and 802 GHz are presented     

MSW applications for phased array antennas

A potential application of MSW technology lies in the area of time delay for future low-sidelobe wide-bandwidth phased array antennas. High-precision MSW electronically tunable analog time-delay units in transmit/receive modules in phased arrays have the potential of greatly enhancing antenna system capabilities, by increasing instantaneous operating bandwidth and decreasing sidelobe levels, over phased array systems using only phase shifters or switched lines for beam steering and control. This paper provides a status report of MSW time delays for such arrays.     

Thin MBE GaAs millimetre-wave mixer diode using Ge substrate

Thin substrateless MBE GaAs diodes have been processed for mixer applications. MBE growth of an inverted n/n+ GaAs structure on Ge was achieved. The Ge substrate was removed by preferential etching. A noise figure of less than 6.0 dB at 94 GHz was obtained.     

Small H-shaped antennas for MMIC applications

A small short-circuited H-shaped GaAs monolithic microwave integrated circuits (MMICs) patch antenna is presented. Resonant at 5.98 GHz, it is the lowest frequency MMIC patch antenna reported that we are aware of and is intended for short-range communications (e.g., vehicular). Initial experimental and theoretical characterization of the proposed structure has been carried out on soft microstrip substrates. It has been shown that the size of an H-shaped patch antenna can be reduced to as low as one tenth of that of a half wavelength patch antenna resonant at the same frequency, saving valuable substrate space. The resonance frequency, radiation patterns and gain have been investigated. Ground plane truncation effects, which are important for MMIC applications, have been examined using the finite-difference time-domain (FDTD) method     

为低功耗无线应用选择天线

天线是RF系统中的一个重要组件，并且对性能有着重大的影响。高性能、小尺寸以及低成本是许多RF应用最常见的要求。为了满足这些要求，实施一个适当的天线并概括描述其性能特点是非常重要的。本文描述了典型的天线类型并阐述了选择天线时应该考试的重要参数。     

Integrated horn antennas for millimeter-wave applications

This paper reviews the development of integrated horn antennas since their introduction in 1987. The integrated horn is fabricated by suspending a dipole antenna on a thin dielectric membrane in a pyramidal cavity etched in silicon. Recent progress resulted in optimized low and high-gain designs with single and double-polarizations for remote-sensing and communication applications. A fullwave analysis technique have resulted in an integrated antenna with performance comparable to that of waveguide-fed corrugated horn antennas. The integrated horn design can be easily extended to large arrays for imaging and phased array applications while still leaving plenty of room for the rf and w processing circuitry. Theoretical and experimental results at microwave frequencies and at 90, 240 and 802 GHz will be presented.     

Influence of residual air gaps on characteristics of circularly polarised aperture-coupled millimetre-wave microstrip antennas

The influence of residual air gaps located between the two substrates of aperture-coupled printed antennas is investigated theoretically and experimentally in the 60 GHz band. It is shown that the input impedance and the axial ratio of thin-film circular polarisation patches and arrays are strongly altered by small gaps a few micrometres thick. An alternative configuration, comprising two ground planes and compatible with photolithographic processes, is then proposed to overcome this drawback.