My Research Projects

Project:  Design of a Transceiver System based on Multi-Technology

mtm

 Design and Signal Integrity (SI) analysis of high-speed interconnects that includes SATA and USB-3 connectors integrated with RF board differential line traces by applying interoperability feature. SATA to USB data transfer module is characterized to reduce crosstalk, reflection, and power-distribution noise problems that can cause false signal switching. SATA to USB data transfer module is characterized to reduce crosstalk, reflection, and power-distribution noise problems that can cause false signal switching. The design process reduces design cycle time significantly for SI analysis.

Project:  Chaff RCS Modeling using Python Scripting

chaffThis project features an RCS analysis that includes a chaff cloud, generated using Python Scripting.Scattering characteristics of chaff using a cloud of strip dipoles has been studied in presence or large target. The influence of mutual coupling between the dipoles is taken into account. Randomly oriented and distributed chaff cloud is generated using automated script. Both monostatic and bistatic RCS of chaff cloud in presence of 41 meter large aircraft is calculated using Finite Difference Time domain (FDTD) solver. It has been shown that complicated chaff cloud can be modeled and analyzed without any approximations or simplifications, in a relatively reasonable time, using the electromagnetic Finite Difference Time Domain (FDTD) solver.

Project:  Design of Electromagnetic Band Gap (EBG) Metamaterial Structures

ebg5

Designed a Triple-bandgap Uni-planar EBG Structure for Antenna Applications. This is design in EMPro. Metal pattern is formed by etching several properly shapes in the metal surface of the Uni-planar compact (EBG) cell to introduce three bandgap. Structure is printed on FR4 dielectrics slab with dielectric constant of 4.4 and thickness of 1.6 mm. Electromagnetic band-gap structure has periodic arrangement of dielectric or magnetic materials that result in the formation of stop bands in the microwave frequency region are called Microwave band gap structures or Electromagnetic band-gap structure. These structures are typically realized by periodic dielectric substrates and various metallization patterns.

Project:  Multimode Extractor and Converter with Dual Monopulse Tracking System along with two Communication Channel

tr1A Multimode Monopulse Tracking Feed chain for satellite antenna is designed using 3D Finite Element Method (FEM) electromagnetic solver that very accurately calculated higher orders modes propagating in a feed structure. A multi-mode extractor couples first five circular waveguide propagation modes TE21, TE21*, TM01, TE11 and TE11* that includes the three tracking signals (i.e. sum signal, elevation signal, and azimuth signal) used in a high-frequency monopulse tracking system and two communication channels for transmitting and receiving signal at different band. Complete integrated feed chain simulation has been performed with FEM solver.

Project:  SIW Cavity-Backed Antenna and Filter

 siw3In high frequency applications, microstrip devices may not be efficient, and because wavelengths at high frequencies are small, microstrip device manufacturing requires very tight tolerances. At high frequencies, waveguide devices are preferred, however the manufacturing process is more expensive. Therefore a new concept has emerged: substrate integrated waveguide (SIW).A dielectric filled waveguide is implemented as a substrate integrated waveguide using vias for the side walls of the waveguide. A cavity backed path antenna and Filter has been designed using these technolgies . These kinds of antennas have better performance because they suppressthe propagation of surface waves, increase the bandwidth, decrease end-fire radiation, decrease cross-polarization radiation and increase the applicable frequency range.

Project:  High Speed SATA (Serial ATA) Connector EM Simulation

sata3Serial ATA (SATA) interconnect is replacing Parallel ATA(PATA) interface for faster data rate, smaller form factor, and probably lower cost design. Due to the faster data transfer rate, a successful interconnect design such as SATA to PCB interface is crucial to the successful design wins. Designers must include electromagnetic effect of SATA connector together with board traces in 3D EM simulations for accurate signal integrity analysis.Full-wave analysis (S-parameter Calculation) of SATA connector is necessary to get correct behavior of connector at higher frequency.

Project:  Design of Planar Antennas for Wireless Applications

wire6Design of Planar Antennas for Wireless Application  has been done. Design concepts have been taken from IEEE latest papers and simulated results of our tool have been compared with published/measured/other tool results. These planar antennas cover various wireless applications like Mobile antennas, Bluetooth, WLAN, LAN, GSM band, Antenna Diversity, PCS, DCS, IMT, GPS, RFID, WiMax etc. Planar antennas, including microstrip and printed antennas, metal-plate antennas, ceramic chip and dielectric resonator antennas have a low profile hence, these antennas have extensive applications in mobile systems (such as 900/1800 MHz bands), wireless local area networks (WLANs, such as 2.4/5.2/5.8 GHz bands), ultra-wideband (UWB, such as 3.1 ~ 10.6 GHz band) communications

Project:   Four channel concentric Coaxial-line Rotary Joints (C/Ku Band) 

rj3 4-channel C/Ku-band coaxial rotary joint has been designed axially to achieve the desired four-channel operation. To achieve proper field symmetry, the design is based on a coaxial microwave line where the TEM mode of the electromagnetic field is propagated.  Multiple rotary channels have been incorporated the concentric stacking of simple coaxial forms. The joint to be described operates in the TEM mode and has low SWR and insertion loss over a wide band of frequencies. It also has no dead spots, showing only negligible variations in impedance and transmission characteristics with rotation. Multisection doorknob type transition is used to obtain broadband performance.

Project:  Corrugated Horn at 21, 37 and 60 GHz

corrugatedWide-band compact corrugated horn is widely used for satellite communications due to the virtue of  low cross-polarization, high efficient in power, the point of phase is independent of frequency, equal power level of e plane and h plane ,low reflection in crookneck of horn, compact configuration and light weight. Corrugated horn antenna has been designed for -12 dB taper with half cone angle of 20 deg for 60 GHz. Total length of antenna was 6 lambda. A parabolic profile has been chosen in the design. Other corrugated feed horn has been designed in 21 and 37 GHz band for multi-feed reflector antenna.

Project:  Multi Feed Reflector Antenna Design for Polarimetric Radiometer Antenna

An offset fed reflector antenna of 1.8m has been realized. There were 11 feeds to cover different frequency bands (6.8 GHz, 10.7 GHz, 18.6 GHz, 22.8 GHz and 37 GHz). F/D was selected 1 with different feed tapers in different frequency bands. Polarimetric radiometer system is used for ocean wind vector sensing. Ocean wind speed and direction can be assessed with a Polarimetric radiometer system measuring the full set of Stokes parameters. Polarimetric antenna requires very high beam efficiency hence realization of feed arrangement is critical job to get very high beam efficiency.

Project:  Polarizer design at 37 GHz

A dielectric loaded polarizer has been designed at 37.Polarizer converts incident orthogonal linear polarized fields into orthogonal circular polarized fields with low insertion loss and low axial ratio. This waveguide polarizer is for GHz for multi-feed radiometer antenna consisting of a waveguide section, with circular cross-section, being equipped with two terminal flanges for connection to other circular guides. A certain number of elliptical irises are arranged inside at regular intervals, resting on parallel planes and all oriented in the same way, i.e. with their longer axes all belonging to the same axial plane to change to phase of TE10 mode.

Project:   60 GHz TM01 mode circular polarized Tracking Feed

mmtrack2 For circularly polarized beacon only one higher order mode for difference pattern is required for tracking information. Higher order mode may be TM01, TE21 or TE01.In this configuration TM01 mode is used for difference pattern while dominant TE11 mode gives sum pattern information. Coupler consist a two-arm turnstile junction.         E-plane folded hybrid junction is tuned for optimum performance at 60 GHz. The dual ports of hybrid respond to TM01 mode by exciting only the H-port. Similarly, the hybrid responds to the TE11H mode by exciting only the E-port. Thus the two modes are separated. The TM01 mode signal is available at H-port of the E-plane folded hybrid junction while the TE11 mode is available at the E-port of E-plane folded hybrid junction, responding only the sum signal.

Project:  Dual Channel Waveguide Rotary Joint in Ku-Band

The design relates to the development of a compact dual channel rotary joint at Ku-band. In this a circular waveguide act as primary waveguide and rectangular waveguide act as the secondary waveguide. Dual channel rotary joint is developed at Ku-band using dual channel mode transducers exciting TM01 and TE01 modes in the circular waveguide.  Circular waveguide transitions employing probe for coupling. Multi-section ridged waveguide transformers to excite TM01 in the circular waveguide and slots coupling at the periphery of circular waveguide to excite TE01 mode in the circular waveguide.

Project:  Multi-Mode (TE21) Monopulse Antenna Tracking Feed at Ka-Band

This invention relates to the development of a unique compact multimode couplers supporting using rectangular and circular waveguide. The mode coupler including three waveguide propagation modes TE21, TE21*, TE11 the three tracking signals (i.e. sum signal, elevation signal, and azimuth signal) used in a high-frequency monopulse tracking system and for transmitting a signal at a different This invention is based on amplitude and phase characteristics of the higher-order TE21 mode excited in circular waveguide by two longitudinal slots milled in the circular waveguide. Multimode tracking system is used to track satellites transmitting linear beacon signal, for inter-satellite links and for ground earth station antennas to track target.

Project:   Ortho Mode Transducer (OMT) Design at 13, 37, 60 and 94 GHz

omt2An orthomode transducer is commonly referred to as an OMT, and commonly referred as a polarization duplexer. Such device may be part of a reflector and VSAT Antenna Feed. Ortho mode transducers serve either to combine or to separate two microwave signal paths.  I designed various kind of OMTs for in different frequency bands ( 13 GHz, 37 GHz, 60 GHz and 94 GHz). I have selected almost all design models for OMT that include stepped transition, Smooth transition, branchline coupled and septum type OMT to desires frequency band either narrow band or broad band OMT.

Project:   High Power dual Polarized Shaped Beam Array Antenna

sar2Designed and developed a dual polarized shaped beam antenna for airborne SAR. Multilayer stacked printed antenna with electromagnetic coupling is chosen as radiating element for wide bandwidth and low cross polarization. Shaping in elevation plane is achieved by obtaining the complex excitation distribution employing null perturbation technique. Many sets of coefficients giving same power patterns were obtained and the one, which gave minimum current taper ratio, is selected for the realization of antenna. A planar array of 8 X 16 elements is designed and developed at C band.

Project:    Square-X Beamforming Network for High Power Application

Square-X beamforming network has been used in place of normal waveguide power divider due to compactness in size and high power chandelling capability. Design of square coaxial line begins with choice of impedance with which patch is to be fed and it is taken as 50W line and with outer dimension a-9mm and inner dimension b-3.5mm. Initial design of T junction was carried out using the formulation available in literature. Final optimization was carried out using Finite element based software. Waveguide to square-x transition has been realized using probe coupling. The depth of the probe and its distance from the short is critical for the performance. The optimization is carried out for center frequency 5.35 GHz.

Project:    E-Plane and H-Plane Waveguide Power Design in Ka-Band

p6_eplane

As a part a TDP of “Beam Forming Network” in C and k-band I realized E-plane and H-plane waveguide Tee using WR42 to minimize feeder loss of microstrip antenna in comparison to microstrip line. Then with the combination of E and H-plane Tee, created a 4-way feed network to feed an array of 2×2 microstrip patch radiator achieving low feeder loss. Also for this work, develop an impedance transition model between waveguide and 50 ohm microstrip line to feed antenna array

Project:   Waveguide Feeder Network using Inline Waveguide (WR28, WR42 & WR157) to Co-axial Line transition

p5_trans

Normally Waveguide has large output impedance, (greater than impedance of free space) so it is required to reduce the Waveguide impedance to match the impedance of coaxial cable (50 ohms). The standing wave that results from a mismatch causes a power loss, a reduction in power handling capability and an increase in frequency sensitivity. Impedance changing structure is therefore employed for matching. Waveguide irises can be used for this purpose, which introduce inductance or capacitance into a Waveguide. At resonance frequency iris acts as a high shunt resistance, above or below resonance, the iris acts as a capacitive or inductive reactance. In line transition techniques has been used to match waveguide impedance to co-axial line impedance.

Project:  Dual Band Shared Aperture Array Antennas

p4_dual

This Multi band antenna operates in C and X bands. For X band slots are used as radiators and in array they are fed by combination of Series and corporate feeding networks (hybrid feeding technique). For C band Patches are used as radiators and are fed by combination of series and corporate feed network. Both the antennas are sharing the same aperture . C and X band radiating elements are arrange in a fashion so that it does not block radiation pattern of each other. One C-band patch radiator is placed between four X-band slot radiators.

Project:   Multilayer Microstrip Active Phased Array Antenna for Satellite

p3_risat

In  this antenna, physical aperture size of 6 meter x 2 meter was obtained to yield the required beam width in principle planes. It consists of three deployable panels of size 2 meter X 2 meter. Each panel contains four tiles each with the size of 1meter x 1 meter. In order to scan the beam in elevation plane, a distributed antenna concept is planned with 24 linear arrays each having 24 elements. All the 24 linear arrays are fed at the center by T/R modules for digital amplitude and phase control. The most critical aspect of design is the realization of dual polarized feed networks for very large size linear array, which requires innovative design approach.

Project:   Multi-career signal source generator (Test Lab Equipment)

p2_lab

Communication satellites like INSAT and GSAT carry number of transponders in various bands like S, C and Ku. These transponders are subjected to rigorous testing both at sub-system stage as well as at integrated payload stage. Some of the tests like Output power test, Input-output transfer characteristics, group delay response, inter-modulation etc., are carried out for individual channels in isolated mode and hence give the performance of various channels in stand-alone mode only but it is very important to estimate the performance of various channels when all the channels are energized and are active simultaneously, especially in power and gain stability related tests.

Project:  Design of Wilkinson power divider

p-wilcon

 A 3-dB Wilkinson power divider with a surface mount chip resistor is designed for a center frequency of 5.35 GHz. This divider has a 50 V-microstrip line with .983 mm width for easy fabrication. The two quarter-wavelength long sections of the divider have an impedance of 71.7V , which yields approximately w-0.545 mm andeeff-2.94. Based on the latter value of the effective dielectric constant, the length of the lambda/4 sections is found to be8.18 mm at 5.35 GHz. A large complex feeder network of 1:32 element fabricated using this -3 dB Wilkinson power divider.

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