The current issue of the IETE Journal of Research (Vol.62, No.1, January–February 2016) contains 15 articles. These articles present on-going research and developments taking place in the broad areas of electrical engineering. Specifically in this issue, the papers have been grouped in the area of electromagnetics and microwave engineering.
The paper titled ‘Design and simulation of a zinc oxide thin film bulk acoustic resonator filter for 2.6 GHz band applications’ presents the design and performance analysis of zinc oxide based thin film bulk acoustic resonator band pass filters for 2.6 GHz band. Two band pass filters of third-order and fifth-order have been studied in detail. The authors explain a method to reduce the high insertion loss of the filter. The utility of the design is for use in mobile broadband services in the 2.5-2.69 GHz band.
The next paper, ‘Dual band circularly polarized monopole antenna design for RF energy harvesting’, explores the potential of harvesting environmental RF energy from cell towers. It gives the antenna geometry design of a multiband microstrip monopole antenna with circular polarization for RF energy harvesting in the CDMA and GSM bands. The simulated structure performance is shown to match closely with a prototype realization of the antenna performance.
In the paper ‘Equivalent circuit model of resonant-EBG band stop filter’, the authors give an equivalent circuit model of a uni-planar electromagnetic band gap (EBG) structure. The results of the equivalent circuit are compared with those of full-wave simulator. It is observed that the resonant frequency of the structure depends on dimensions of the meander line and inter-digital capacitor. The equivalent structure provides an understanding of the structure and a simplified method for determining these values for the required resonant frequency compared to EM simulations.
In the paper ‘Co-array based synthetic aperture active imaging at millimeter wave frequencies’, the authors present the theoretical and experimental study of imaging technique based on synthetic aperture using linear and circular arrays and beam forming at millimeter wave frequencies. The study includes multiple target scenarios in the 2-D image plane. The experimental validation of active imaging performance is based on bistatic setup with horn antennas that have been used for transmission and reception.
The next paper, entitled ‘Performance of a double uniform circular array in a three-dimensional environment’, investigates double uniform circular arrays (DUCA) for 3-D scenarios and small communication terminals. The DUCA is studied for spatial fading correlation (SFC) between antennas. It is observed that DUCA can reduce SFC between antennas and thereby increase capacity compared to uniform circular arrays.
The paper ‘Performance analysis of MIMO systems with antenna selection over generalized κ-μ fading channels’ gives the outage probability expression and symbol error rate for MIMO systems having transmit antenna selectivity over generalized IID κ-μ fading channels. These are useful for analyzing receivers based on maximal ratio combining or selection combining. The exact BER for BPSK, BFSK and M-ary PAM modulation schemes are derived. Also, approximate BER is derived for M-QAM and QPSK schemes. The study brings out for such channels, the variation of channel capacity with increased strength of line of sight component and decreased severity of fading.
The following paper, ‘Higher order mode analysis of dual-post discontinuity in a circular waveguide’, analyses the scattering characteristics of two radially directed posts in an oversized circular waveguide for application such as conjugate matched feed for suppression of cross-polar component in offset reflector antenna system. The dual-post discontinuity oriented in arbitrary angular spacing in a circular waveguide is analyzed using Galerkin's method. The simulation results have been compared with an experimental hardware setup.
The paper ‘Ultra-wideband bandpass filter with cascaded low pass filter on multilayer liquid-crystal polymer substrate’ presents the design of an ultra-wideband band pass filter with extended upper stop band with frequency band selection in the 1.0 to 20 GHz band on multilayer liquid-crystal-polymer substrate. The composite low pass filter has wide rejection band. The results of the fabricated filter are presented in the paper and compared with the simulated results.
In ‘A novel SPDT rotary RF MEMS switch for low loss and power efficient signal routing’, the authors present the design of a low loss port-to-port high isolation electro-thermally actuated single-pole double-through (SPDT) RF MEMS switch. The study is relevant for wireless communication applications. A latching mechanism is investigated wherein the switch consumes power during transition between states. FEM simulation based performance is reported in terms of insertion loss, port-to-port isolation, operating voltages and power consumption. A proposed fabrication process is also outlined in the paper.
The following paper, ‘Determination of polarization of microwave signals by lock-in infrared thermography’, describes a method for the detection of polarization of microwave signals using infrared thermography. It permits the visualization of EM field intensity on a plane using an absorption screen of carbon-loaded polymers whose temperature increases due to the EM waves falling on the screen. The method of frequency modulation of the microwave source is used for lock-in thermography with increased thermal resolution. The method is simulated in software and compared experimentally with linearly, circularly, and elliptically polarized patch antennas at 8 GHz.
In the paper ‘A 3.0-10.0 GHz UWB low-noise amplifier with forward body bias technique’, a low noise amplifier for ultra-wideband is given. The design is based on cascaded common source stage shunt-shunt resistive feedback architecture. The resistance shunt-shunt feedback acts as two parallel RLC loads from the input with one branch set to achieve input matching at lower frequency and the other branch tuned to obtain the desired input matching at higher frequency. The paper proposes resistor-capacitor extracted method that is compared with other state-of-the-art methods in terms of noise figure and voltage consumption.
The following paper on ‘Embedded digital MIMO radar using SDR for target detection and RCS measurement’, gives the design of spread-spectrum based digital MIMO SDR radar of small size and low cost with the aim of removing the complexity associated with hardware instrumentation. The radar helps achieve a good RCS pattern that is not achieved with SISO radar. The paper describes the experimental setup and the performance results obtained from the setup.
In the paper, ‘A novel metamaterial MIMO antenna with improved isolation and compact size based on LSRR resonator’, the authors have given the design of a two-element MIMO meander-line antenna using a metamaterial Labyrinth split-ring resonator (LSRR) with emphasis on improving the isolation performance and compactness of size. The MIMO antenna is designed for 2.4 GHz with 150 MHz bandwidth and targets wireless LAN communications applications.
The paper, ‘Low-power CMOS power amplifier for 3.1-10.6 GHz ultra-wideband transmitter’, provides the design and implementation aspects of a low-power UWB power amplifier in 0.18 μm CMOS technology. It uses forward body biasing to reduce power consumption. The performance analysis using post-layout simulations is given in terms of input and output return loss, average power gain and power consumption.
The paper, ‘Compact electromagnetic band gap structure with defected ground’, gives the design of a compact defected ground mushroom electromagnetic band gap structure. The emphasis of the design is on the compactness of the device. The paper gives the simulation study results of low pass filter with wide stop band and compares it with the measurement results.