Christopher S

Data fusion technique combines data from two similar sensors placed in different location in order to reduce the error in filtered state estimate. In this paper, state vector fusion (SVF) and measurement fusion (MF) are used to fuse the bearing measurement and also to fuse the derived heading measurement. The derived heading from bearing measurement increases the accuracy of target state estimate. Here, the Lagrange three point difference (LTPD) method has been proposed to derive heading from the set of bearing measurements. Two sensors with single target scenario are considered and the heading parameters are derived for each sensor. The bearing and derived heading measurements from two different sensors are fused using SVF or MF and then nonlinear Extended Kalman filter (EKF) is used to obtain the optimized state estimate. Simulations have been carried out in order to compare the SVF and MF fusion techniques for the bearing measurements as well as the derived heading parameters using existing centered difference (CD) and proposed LTPD.

In this paper, a 2 inverted U-slot integrated rectangular patch antenna array is proposed that can be used for S band applications i.e., radar applications, communication and wireless networks. In the proposed antenna design 2 inverted U slots are introduced in the patch to improve bandwidth providing a bandwidth of 150 MHz and gain of 4.08 dBi resonating at 3.3 GHz. Furthermore, 4 X 4 antenna array is fabricated on 1.6 mm thick FR4 substrate with dielectric constant 4.4 providing a gain of 14.2 dBi. Ansys HFSS is used for antenna simulation and a prototype is fabricated and tested.

A CMOS down-converter with the combination of Gilbert Cell mixer and modified low voltage design technique using LC-balun is demonstrated in this paper. This forms a down-converter duo of mixer and balun. The RF, LO, and IF port frequencies are 3 GHz, 2.4GHz, and 600MHz, respectively. The measurement results of the proposed mixer-balun duo exhibit 13dB of conversion gain, -7.9 dBm of Input 1-dB compression point (P1dB), 2.51 dBm of Input 3rd order intercept point (IIP3), 3.8 dBm of Output 3rd order intercept point (OIP3) -43dB RF-IF, -42dB LO_IF Isolation and 1.2V supply voltage. This mixer-balun duo was fabricated at 65nm. CMOS technology. It can provide a 4 dB conversion gain even without connecting the LC-balun and 1.2V supply voltage is utilized.

The design details of K band 6 bit digital phase shifter circuit in 65nm CMOS technology (MMIC) for phased array antennae in general and active phased array antennae in particular, are presented in this paper. The circuit is composed of Si CMOS switches and filter based phase shifting network. The 6 bits are designed individually using the lumped equivalents and then connected together. The switches form an integral part of the design. The parasitic impedances associated with the switches are compensated in the design. With 6 bits, a total of 64 states are derived with different switching combination, and coverage of 360 is achieved. The insertion loss is observed to be -13± 6.5 dB and the input and output matching was greater than 5 dB over the band of 19-20 GHz. The RMS phase error achieved is 3° at the centre frequency of 20 GHz. The area of the design is 1.255 mm × 0.424 mm, the circuit operates at 1.2V and the power consumed is almost low.

In this paper, a miniaturised wide-band circular slot cut patch antenna with broad beam width is proposed that can be used for X band applications i.e., radar, satellite and wireless computer networks. In this proposed antenna design, initially a circular patch is taken and then 2 circular slots are removed from the patch to get wide band and broad beam-width providing 1.67 GHz (17%) of bandwidth, beam-width (HPBW) 100° in E-plane (i.e., φ=0o) and 96° in H-plane (i.e., φ=90o) and more than 100° beam-width for higher frequency within the operating bandwidth. The proposed design provides 5.5 dBi-4.43 dBi of gain over the band. For miniaturising and furthermore improvement of bandwidth and beam-width capacitive via fence is introduced around the patch antenna providing 2.03 GHz (22%) of bandwidth and more than 125° of beam-width. Ansys HFSS is used for antenna simulation and a prototype has been fabricated.

A novel analysis to compute the admittance characteristics of the slots cut in the narrow wall of a rectangular waveguide (also called edge slot) is presented. The slot aperture field is expanded in terms of entire domain sinusoidal basis functions and is solved using Galerkin's method. The computed results have been compared with the measured data published in the previous literature to validate the present analysis. The validity of representing the edge slot as a shunt element is examined and an alternate way of representing the edge slot is suggested as being more accurate. © 1998 John Wiley & Sons, Inc.

A novel photonic sub-Nyquist based wideband frequency measurement system based on a pulsed laser, a set of interleavers and a binary deduction algorithm is proposed and verified with simulations.

In general, bearing measurements combined with the derived heading increases the accuracy of target state estimate in bearing only tracking (BOT). Here, Lagrange five point difference (LFPD) method is proposed for deriving the heading measurements. This method is compared with Lagrange three point difference (LTPD) and centered difference (CD) method by considering the scenario of two sensors tracking a single target. The bearing and derived heading measurements from two sensors are fused using measurement fusion (MF) technique. The nonlinear Extended Kalman filter (EKF) is implemented using fused measurement to obtain the optimized target state estimate. Performance analyses are made between LFPD compared with LTPD and CD by considering without and with fusion technique. Simulation results indicate MF-LFPD performs comparatively better.

As the communication industry is currently undergoing a major overhaul to accommodate greater bandwidth and higher data-rate to meet the rapidly growing data demand; terahertz range of frequencies from 100 GHz to 3 THz are being investigated as a possible replacement of the conventional mm-wave technology. In this paper, the technological readiness of Indian research community in this specific direction have been examined. The research development strategies that are required to gain momentum towards achieving a viable technology standard in THz communication in India are discussed. Technology recommendations towards product development required for initiation and advancement in THz communication are presented. We have also introduced a design of a short-range THz communication configuration in conclusion, based on recent reports of successful realisation of THz communication which could be utilised for immediate realisation using commercially available resources.

Multidynamic radar (MDR) configuration is emerging as state of the art in the field of airborne radar, where several airborne radars work in a coordinated manner. MDR systems provide better spatial diversity and resistance to other vulnerability in combat scenario. This provides high performance for operational requirement compared to multistatic, bistatic, or monostatic radar. For last few decades, stealth technology has been one of the most widely used approaches for target hideout from radar systems. This technology uses the concept of low-observable principle to reduce the radar cross section in the direction of radar. Earlier, ground-based radars, like bistatic radar or multistatic radar, were used to counter such target hideout. Airborne radar has its own advantages for better visibility and coverage for airborne surveillance. In the proposed MDR, the transmitters (Tx) and receivers (Rx) are placed on airborne platform, such as aircraft or on unmanned air vehicles. The operational challenges for MDR configuration is how to exploit the Tx-Rx sensor dynamics for benchmarking performance. In this letter, the MDR system-geometry is considered as a set of bistatic radar at a given time and simulated with all possible airborne Tx-Rx pair combinations for evaluating MDR performance. The simulation is also done for a proposed orthogonal frequency-division-multiplexing linear-frequency-modulated-based waveform design using a derived ambiguity function for the proposed MDR scenario. A design methodology is shown for an MDR to achieve phase synchronization across the airborne Tx and Rx platform.