Miniaturized microstrip lowpass filter using cylindrical-shaped resonators for integrated applications

A novel compact microstrip lowpass filter is presented in this paper. The structure uses stepped impedance and radial patches and it has the ??3 dB cut-off frequency at 4.39 GHz. The proposed lowpass filter has a wide rejection band from 6 to 30 GHz with rejection level more than ??20 dB. It has also other advantages such as: low insertion-loss <?0.1 dB and high return-loss more than 22 dB in 80% of the passband. The circuit size of the presented filter is about 90 mm². Such important advantages make the proposed lowpass filter applicable to be integrated in many high frequency circuits such as power amplifiers, oscillators, couplers and power dividers. It also can block the unwanted video transmitter interference nearby 4 GHz such as implementing between transmitter and antenna. The lowpass filter has simulated and fabricated and a good agreement was seen between the simulation and fabrication results.     

Ka Band Broadband Fourth Harmonic Image Rejection Mixer

This paper presents the design and implementation of Ka band broadband hybrid integrated image rejection mixer with a fourth harmonic mixer as unit mixer. Detailed design and analysis have been carried out. The mixer was fabricated by hybrid microwave integrated circuit (HMIC) process based on the thin film ceramic substrate which can reduce the cost compared to monolithic microwave integrated circuit (MMIC). The measured results showed conversion loss less than 11.2 dB and image rejection ratio (IRR) more than 20 dB in 4 GHz RF bandwidth. It can also play the role of up-converter from the test data.     

Antennas for Short Distance Communications in Cryogenic Environment

Sets of bow-tie antennas, used in a single emitter-receiver near-field configuration and in array configuration, have been studied to be used as wireless means to transmit 8–12 GHz microwave signals from the cold stage of a cryogenic system to a room-temperature processing unit. Indeed, the absence of heat conduction allows increasing the performance of cryogenic systems and open the way to multichannel microwave systems that are necessary for imagers. Transmission loss has been found to be lower than 3 dB over a 1.5 GHz bandwidth while crosstalk in the array configuration is kept below ?20 dB when antennas are located at around 90 mm transversally from each other.     

225–255-GHz InP DHBT Frequency Tripler MMIC Using Complementary Split-Ring Resonator

In this paper, a novel design of frequency tripler monolithic microwave integrated circuit (MMIC) using complementary split-ring resonator (CSRR) is proposed based on 0.5-μm InP DHBT process. The CSRR-loaded microstrip structure is integrated in the tripler as a part of impedance matching network to suppress the fundamental harmonic, and another frequency tripler based on conventional band-pass filter is presented for comparison. The frequency tripler based on CSRR-loaded microstrip generates an output power between ?8 and ?4 dBm from 228 to 255 GHz when the input power is 6 dBm. The suppression of fundamental harmonic is better than 20 dBc at 77–82 GHz input frequency within only 0.15?×?0.15 mm² chip area of the CSRR structure on the ground layer. Compared with the frequency tripler based on band-pass filter, the tripler using CSRR-loaded microstrip obtains a similar suppression level of unwanted harmonics and higher conversion gain within a much smaller chip area. To our best knowledge, it is the first time that CSRR is used for harmonic suppression of frequency multiplier at such high frequency band.     

Structural, Magnetic, and Microwave Properties of SrFe12−x (Ni0.5Co0.5Sn) x/2O19 Particles Synthesized by Sol–Gel Combustion Method

This study is intended to evaluate the structural, magnetic, and microwave properties of Ni-Co-Sn-doped strontium hexaferrite SrFe_12?x (Ni_0.5Co_0.5Sn) _x/2 O₁₉ particles with x = 0 to 2.5 synthesized by a sol–gel combustion method. These particles were evaluated to characterize the structural, magnetic, and reflection loss properties of prepared samples by use of x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FTIR) spectroscopy, vibrating-sample magnetometer (VSM), and vector network analyzer. The XRD results confirmed the presence of strontium ferrite phase with magnetoplumbite structure in all synthesized samples. The results of FTIR analysis indicated the formation of functional groups such as metal-oxygen (Sr-O and Fe-O) and carboxylic groups during the sol–gel process. In addition, FE-SEM micrographs indicated that submicron particles with different morphologies such as spherical, pyramidal, irregular, and hexagonal platelet shapes appeared in the structure. According to hysteresis loops, magnetization and coercivity decreased due to occupation of Ni-Co-Sn cations at low levels of substitutions. The microwave absorption characteristics of this ferrite were investigated in the 8 GHz to 12 GHz frequency range. The sample with 80 wt.% ferrite content showed a maximum reflection loss of ?29 dB at 9.6 GHz with 4 GHz bandwidth through the entire frequency range of 8 GHz to 12 GHz for absorber thickness of 1.5 mm. Based on microwave measurements of reflectivity, this material with the expressed chemical composition could be proposed as a good choice for electromagnetic compatibility and other practical applications such as microwave absorption at high frequencies.     

Compact microstrip lowpass filter with wide stopband and sharp roll-off using tapered resonator

In this article, a novel microstrip lowpass filter (LPF) with specifications such as sharp cut-off, wide stopband, low insertion loss and high return loss using tapered resonator is presented. The LPF has cut-off frequency of 1.11 GHz, where unwanted harmonics are suppressed by novel tapered cells. The bandwidth is enhanced, and the size is reduced as compared to the conventional tapered filter. The transition band is approximately 0.29 GHz from 1.11 to 1.4 GHz with corresponding attenuation levels of –3 and –20 dB, respectively. The stopband with greater than –20 dB rejection is from 1.4 to 8.9 GHz, insertion loss in the passband is less than 0.1 dB, return loss is less than –18 dB and the overall size of the filter is 0.12 × 0.073 λ_g. The proposed filter is fabricated and measured. The simulation and measurement results are in good agreement. This LPF is designed for microwave communication applications, especially wireless video transmitters.     

Analysis and Design of a Novel W-band SPST Switch by Employing Full-Wave EM Simulator

In this paper, a W-band single pole single throw (SPST) switch based on a novel PIN diode model is presented. The PIN diode is modeled using a full-wave electromagnetic (EM) simulator and its parasitic parameters under both forward and reverse bias states are described by a T-network. By this approach, the measurement-based model, which is usually a must for high performance switch design, is no longer necessary. A compensation structure is optimized to obtain a high isolation of the switch. Accordingly, a W-band SPST switch is designed using a full wave EM simulator. Measurement results agree very well with simulated ones. Our measurements show that the developed switch has less than 1.5 dB insertion loss under the ??on?? state from 88 GHz to 98 GHz. Isolation greater than 30 dB over 2 GHz bandwidth and greater than 20 dB over 5 GHz bandwidth can be achieved at the center frequency of 94 GHz under the ??off?? state.     

An ultra low power consumption millimeter-wave voltage controlled oscillator in a 65 nm CMOS-SOI technology

This paper presents an ultra low power consumption 65 GHz LC-VCO dedicated to wireless high data rate applications. It is designed in a 65 nm CMOS SOI process, which improves passive devices behavior. The proposed VCO achieves a frequency tuning range (FTR) of 9.7 % and a phase noise of ?110.86 dBc/Hz at 10 MHz of the carrier. All integrated passive components (including transmission lines and a transformer-based balun) are modeled using advanced electromagnetic (EM) field solvers. The power consumption of the proposed VCO is as low as 1.1 mW when biased by a 0.8-V supply voltage. The FoM of this millimeter wave circuit, whose core occupies a silicon footprint of only 0.047 mm², is ?184.07 dBc/Hz.     

Integrated amateur band and ultra-wide band monopole antenna with multiple band-notched

This paper presents the integrated amateur band and ultra-wide band (UWB) monopole antenna with integrated multiple band–notched characteristics. It is designed for avoiding the potential interference of frequencies 3.99 GHz (3.83 GHz–4.34 GHz), 4.86 GHz (4.48 GHz–5.63 GHz), 7.20 GHz (6.10 GHz–7.55 GHz) and 8.0 GHz (7.62 GHz–8.47 GHz) with VSWR 4.9, 11.5, 6.4 and 5.3, respectively. Equivalent parallel resonant circuits have been presented for each band-notched frequencies of the antenna. Antenna operates in amateur band 1.2 GHz (1.05 GHz–1.3 GHz) and UWB band from 3.2 GHz–13.9 GHz. Different substrates are used to verify the working of the proposed antenna. Integrated GSM band from 0.6 GHz to 1.8 GHz can also be achieved by changing the radius of the radiating patch. Antenna gain varied from 1.4 dBi to 9.8 dBi. Measured results are presented to validate the antenna performances.     

Dielectric Property Measurement of Gold Nanoparticle Dispersions in the Millimeter Wave Range

A quasi-optical transmission-meter is employed to measure the performance of gold nanoparticle dispersions at the W-band (75-110 GHz). A specifically designed liquid sample holder was integrated into the transmission-meter to secure reliable measurement repeatability and an iterative method was utilized to retrieve the dielectric properties from the measured transmission coefficients. Different to some previous results in MHz and GHz range, it was found that the dielectric properties of purified gold nanoparticle (GNP) dispersions did not exhibit marked difference to that of DI-water, which suggests a weak interaction of GNP with EM radiation in the W-band, consistent to the predictions from the effective medium theory and microscopic views. Further work is proposed to explore the dielectric properties of GNP dispersions in the shorter wavelength, such as sub-terahertz, terahertz and infrared range.     

A 65 nm CMOS LNA for Bolometer Application

Modern bolometers generally consist of large-scale arrays of detectors. Implemented in conventional technologies, such bolometer arrays suffer from integrability and productivity issues. Recently, the development of CMOS technologies has presented an opportunity for the massive production of high-performance and highly integrated bolometers. This paper presents a 65-nm CMOS LNA designed for a millimeter-wave bolometer’s pre-amplification stage. By properly applying some positive feedback, the noise figure of the proposed LNA is minimized at under 6 dB and the bandwidth is extended to 30 GHz.     

Millimeter Wave MMIC Low Noise Amplifiers Using a 0.15 µm Commercial pHEMT Process

This paper presents millimeter wave monolithic microwave integrated circuit (MMIC) low noise amplifiers using a 0.15 µm commercial pHEMT process. After carefully investigating design considerations for millimeter-wave applications, with emphasis on the active device model and electomagnetic (EM) simulation, we designed two singleended low noise amplifiers, one for Q-band and one for V-band. The Q-band two stage amplifier showed an average noise figure of 2.2 dB with an 18.3 dB average gain at 44 GHz. The V-band two stage amplifier showed an average noise figure of 2.9 dB with a 14.7 dB average gain at 65 GHz. Our design technique and model demonstrates good agreement between measured and predicted results. Compared with the published data, this work also presents state-of-the-art performance in terms of the gain and noise figure.     

Magnetodielectric Microwave Radiation Absorbent Materials and Their Polymer Composites

Functional radiation absorbent materials (RAMs) can transform incident microwave energy into heat energy, hence being essential to impede reflections of microwaves generated by modern radars in military, aerospace, and commercial applications. For such applications, use of composites is imperative to maintain an optimum bandwidth, enhance the magnetoelectric functional activity, ensure a flexible design, and reduce weight, which can be achieved by tuning the volume fractions of such materials. Use of ferrites is widely recommended for microwave (MW) suppression due to their appropriate magnetodielectric characteristics. This review first describes the requirements for an ideal MW absorber and accurate measurements for quantification of MW absorption. Then, the significance, applications, approaches, and experimental developments of magnetodielectric polymer composite RAMs are presented. Moreover, such composites facilitate exploration of nanoscale functional properties to achieve efficient RAMs. The permeability and permittivity at microwave frequencies, magnetic properties induced by unique elemental doping mechanisms, as well as physical and chemical properties of these composites are also presented. The resonance-dependent absorption condition for different families of magnetic ferrites, as well as the dependence of their magnetic properties on the resonant frequency and their absorption bandwidth (spinels up to 30 GHz, hexaferrites 1 GHz to 100 GHz), are presented for applications. Furthermore, magnetodielectric composites decorated with carbon fillers (carbon nanotubes/multiwall carbon nanotubes, graphene, reduced graphene oxide, etc.) with enhanced microwave absorption properties are discussed. Additionally, core–shell magnetodielectric materials are also discussed in detail. Finally, this review highlights the importance of magnetodielectric polymer composites decorated with conducting materials and core–shell magnetodielectric materials as effective broadband RAMs achieving the primary application requirement of broadband absorption of at least ?10 dB with reduced thickness.     

A wide-locking range ÷3 injection-locked frequency divider using concurrent injection mechanisms

A new wide locking range divide-by-3 injection-locked frequency divider (ILFD) using a standard 0.18 μm CMOS process is presented. The ILFD uses two concurrent injection mechanisms with two independent push–push circuits to extend the locking range. It is realized with a cross-coupled n-core MOS LC-tank oscillator. The core power consumption of the ILFD core is 11.496 mW. The divider’s free-running oscillation frequency is tunable from 4.32 to 3.78 GHz by tuning the varactor’s control bias, and at the incident power of 0 dBm the maximum locking range is 3 GHz (25 %), from the incident frequency 10.5 to 13.5 GHz. The operation range is 3.6 GHz (30.76 %), from 9.9 to 13.5 GHz.     

Wide-locking range ÷3 series-tuned injection-locked frequency divider

A new wide locking range series-tuned (ST) divide-by-3 injection-locked frequency divider (ILFD) using a standard 0.18 μm CMOS process is presented. The ÷3 ILFD circuit is realized with a ST cross-coupled n-core MOS LC-tank oscillator. Two direct-injection MOSFETs in series are used as a frequency doubler and a dynamic linear mixer to widen the locking range. The power consumption of the ILFD core is 10.56 mW. The divider’s free-running frequency is tunable from 3.529 to 3.828 GHz by tuning the varactor’s control bias, and at the incident power of 0 dBm the maximum locking range is 2.3 GHz (21.6 %), from the incident frequency 9.5 to 11.8 GHz. The operation range is 2.5 GHz (23.7 %), from 9.3 to 11.8 GHz.     

基于平面肖特基二极管的平衡式亚毫米波倍频器芯片

基于标准的平面肖特基二极管单片工艺设计了一款平衡式亚毫米波倍频单片集成电路。依据二极管实际结构进行电磁建模,提取了器件寄生参数,并与实测的器件本征参数相结合获得了二极管非线性模型;依据该模型,采用平衡式拓扑结构以实现良好的基波抑制,设计了三线耦合巴伦电桥,并与肖特基二极管集成在同一芯片上,实现了单片集成,提高了设计准确度。芯片在片测试结果表明,在输入功率17 dBm 下,输入频率75~105 GHz范围内,倍频器芯片峰值输出功率达到2.67 dBm。芯片整体尺寸为0.80 mm×0.50 mm。     

A reconfigurable frequency-selective surface for dual-mode multi-band filtering applications

A reconfigurable single-layer frequency-selective surface (FSS) with dual-mode multi-band modes of operation is presented. The proposed structure is printed on a compact 10 × 10 mm² FR4 substrate with the thickness of 1.6 mm. A simple square loop is printed on the front side while another one along with two defected vertical arms is deployed on the backside. To realise the reconfiguration, two pin diodes are embedded on the backside square loop. Suitable insertion of conductive elements along with pin diodes yields in dual-mode multi-band rejection of applicable in service frequency ranges. The first operating mode due to diodes’ ‘ON’ state provides rejection of 2.4 GHz WLAN in 2–3 GHz, 5.2/5.8 GHz WLAN and X band in 5–12 GHz, and a part of Ku band in 13.9–16 GHz. In diodes ‘OFF’ state, the FSS blocks WLAN in 4–7.3 GHz, X band in 8–12.7 GHz as well as part of Ku band in 13.7–16.7 GHz. As well, high attenuation of incident waves is observed by a high shielding effectiveness (SE) in the blocked frequency bands. Also, a stable behaviour against different polarisations and angles of incidence is obtained. Comprehensive studies are conducted on a fabricated prototype to assess its performance from which encouraging results are obtained.     

GaAs active structures with applications to microwave wideband 90° phase shifters and bandstop filters

Lumped-element second-order active filters are presented which can either be tuned to an all-pass response and then especially used in 90° phase shifters, or tuned to a bandstop response. Their structures have been chosen so that they can be easily implemented in the microwave domain. Preliminary simulations have shown that the filter having the highest-frequency capabilities results in a 90^° phase shifter operating up to the (6 GHz, 1O GHz) band, and that its centre frequency can be tuned up to 15 GHz when it is used as a bandstop filter.     

Towards THz Communications - Status in Research,Standardization and Regulation

In the most recent years, wireless communication networks have been facing a rapidly increasing demand for mobile traffic along with the evolvement of applications that require data rates of several 10s of Gbit/s. In order to enable the transmission of such high data rates, two approaches are possible in principle. The first one is aiming at systems operating with moderate bandwidths at 60 GHz, for example, where 7 GHz spectrum is dedicated to mobile services worldwide. However, in order to reach the targeted date rates, systems with high spectral efficiencies beyond 10 bit/s/Hz have to be developed, which will be very challenging. A second approach adopts moderate spectral efficiencies and requires ultra high bandwidths beyond 20 GHz. Such an amount of unregulated spectrum can be identified only in the THz frequency range, i.e. beyond 300 GHz. Systems operated at those frequencies are referred to as THz communication systems. The technology enabling small integrated transceivers with highly directive, steerable antennas becomes the key challenges at THz frequencies in face of the very high path losses. This paper gives an overview over THz communications, summarizing current research projects, spectrum regulations and ongoing standardization activities.     

Microwave and Millimeter Wave Characteristics and Attenuation of Clouds over some Malaysian Equatorial Stations

Based on radar range height indicator (RHI) measurements, cloud characteristics in relation to radiowave propagation over three locations in different geographical region in western Malaysia have been presented. It is seen that low cloud occurrence over these locations are quite significant. Cloud attenuation and noise temperature can result in serious degradation of telecommunication link performances. This paper presents cloud coverage in different months, 0°C isotherm height and cloud attenuation results at 12 GHz, 20 GHz, 36 GHz, 50 GHz, 70 GHz and 100 GHz over measurement site. The low level cloud over the measurement sites has been found to occur for many days and nights and particularly in the months of April to May and October to December. Such results are useful for satellite communication and remote sensing application in Malaysia.