Advanced Electromagnetics

Thermal changes in Human Abdomen Exposed to Microwaves: A Model Study

J. Kaur, S. A. Khan, Dr. — Tue, 11 Jun 2019 18:09:02 -0400

The electromagnetic energy associated with microwave radiation interacts with the biological tissues and consequently, may produce thermo-physiological effects in living beings. Traditionally, Pennes’ bioheat equation (BTE) is employed to analyze the heat transfer in biological medium. Being based on Fourier Law, Pennes’ BTE assumes infinite speed of propagation of heat transfer. However, heat propagates with finite speed within biological tissues, and thermal wave model of bioheat transfer (TWBHT) demonstrates this non-Fourier behavior of heat transfer in biological medium. In present study, we employed Pennes’ BTE and TWMBT to numerically analyze temperature variations in human abdomen model exposed to plane microwaves at 2450 MHz. The numerical scheme comprises coupling of solution of Maxwell's equation of wave propagation within tissue to Pennes’ BTE and TWMBT. Temperatures predicted by both the bioheat models are compared and effect of relaxation time on temperature variations is investigated. Additionally, electric field distribution and specific absorption rate (SAR) distribution is also studied. Transient temperatures predicted by TWMBT are lower than that by traditional Pennes’ BTE, while temperatures are identical in steady state. The results provide comprehensive understanding of temperature changes in irradiated human body, if microwave exposure duration is short.

T-Shaped Compact Dielectric Resonator Antenna for UWB Application

A. Zitouni, N. Boukli-Hacene — Tue, 11 Jun 2019 04:03:10 -0400

In this article, a novel T-shaped compact dielectric resonator antenna for ultra-wideband (UWB) application is presented and studied. The proposed DRA structure consists of T-shaped dielectric resonator fed by stepped microstrip monopole printed antenna, partial ground plane and an inverted L-shaped stub. The inverted L-shaped stub and parasitic strip are utilized to improve impedance bandwidth. A comprehensive parametric study is carried out using HFSS software to achieve the optimum antenna performance and optimize the bandwidth of the proposed antenna. From the simulation results, it is found that the proposed antenna structure operates over a frequency range of 3.45 to more than 28 GHz with a fractional bandwidth over 156.12%, which covers UWB application, and having better gain and radiation characteristics.

Dielectric Behavior of Medical PMMA Polymer Filled With Copper Nanobud Particles

I. I. Marhoon, A. H. Majeed, M. A. Abdulrehman — Mon, 10 Jun 2019 13:51:01 -0400

In this paper, the effect of weight fraction and frequency on dielectric properties of polymethylmethacrylate filled with copper nanobud particles is studied. copper nano particles were synthesized by chemical reduction method. The resultant copper nano particles were characterized by UV-Vis spectroscopy and X-ray diffraction (XRD). Results show that the Cu Nps have bud shapes, and their average particle size obtained from the XRD study is 53.78 nm. For the resultant composite materials, such as the dielectric behavior of composite materials reinforced with 5%, 10%, 15%, and 20% weight fractions of copper nanobud particles and frequency ranges of 50, 250, 10³, 10⁴, 10⁵, and 10⁶ Hz at 25 °C were investigated. Results reveal that the dielectric constant, dielectric loss factor, and dissipation factor increased with the increase in weight fraction of copper nanobud particles due to their high conductivity. The dielectric constant, dielectric loss, and dissipation factor decreased with the increase in frequency.

Triple Band Fractal Antenna for Radio Navigation and Fixed Satellite Services using Dragonfly Optimization

A. Kumar, A. P. S. Pharwaha — Mon, 10 Jun 2019 13:37:29 -0400

This study reports the design of a coplanar waveguide (CPW)-fed triple band fractal antenna for radio navigation and fixed satellite services. Reported antenna has low profile, multiband and wideband performance which make it suitable for the radio navigation and fixed satellite services in S band, C band
and X band. Proposed antenna resonates at 2.6GHz, 4.4GHz, and 8.7 GHz having bandwidth of 0.2457GHz, 0.700GHz, and 4.1980 GHz respectively. Maximum
gain for the resonating bands is 3.6 dB, 5.5 dB, and 7.3 dB respectively. Simulated performance parameter of proposed antenna is verified experimentally by testing the fabricated antenna. Measured and simulated results are in good agreement

Design and Development of a Compact Rat-Race Coupler

S. Ahirwar, D. Ramakrishna, V. M. Pandharipande — Mon, 10 Jun 2019 13:16:27 -0400

In this paper, design and development of compact Rat- Race coupler is presented. The device is designed with commercially available semi rigid coaxial cable. The semi rigid coaxial is modified for desired impedance to suit the requirement of Rat- race hybrid coupler. The physical structure of the coupler is in rectangular form instead of the conventional ring form. With this structure, all the ports are available in line on the same side. This eases the integration of the device with other modules or devices in the system. The total area occupied the coupler is reduced drastically by meandering the transmission line. The shielded transmission line provides better port isolation and less radiation loss. Design, implementation and measured results are presented.

An Inherent Limitative Parameter in Spoofing GNSS-Based Navigation Clients

A. Esmaeilkhah — Mon, 10 Jun 2019 12:50:59 -0400

Deception of navigational subsystems of a client, ranging from a hunting GPS receiver to the military-class GNSS receiver onboard of a Cruise Missile, is one of the probable electronic attacks. One of the simplest and practical way too deceive these receivers is to re-broadcast the delayed navigational signals. The authors were studied the feasibility of this method in the “Best” attainable conditions while the generality of study retained. The results from introduced geometrical and mathematical models were used to define the minimum and maximum operational range of Repeater Deception System parametrically. Then the parameters were substituted by information of various GNSS constellations. Investigation of reliability of selected EW scenario concluded the article.

Compact and Low Loss Microwave Idlers for Low Frequency Integrated Circuits

S. Singh, S. C. Bera, D. Pujara — Mon, 10 Jun 2019 11:27:03 -0400

Two design methodologies for realization of low frequency (less than 20 GHz) compact and low loss microwave idlers have been proposed in this paper. Such idlers can be used for realizing low frequency higher order (6X or more) harmonic mixers or multipliers on monolithic integrated technology. Low frequency higher order harmonic mixers or multipliers are generally avoided due to higher losses and board space consumed by multiple idlers. The present proposed methods of idler design are based on realization of idlers by combining distributed microstrip transmission line and lumped components. The approach helps in transmitting the desired frequency with lower insertion loss and providing more rejection to the undesired frequencies. The design proposal has been demonstrated by designing an idler for 3 GHz LO side of a 6X harmonic MMIC mixer. This mixer utilizes 6th harmonic of the 3 GHz LO for generating 18 GHz output RF signal by frequency mixing. The idler for 3 GHz LO rejects dc, IF and selective even harmonics of LO; 6 GHz, 12 GHz and 18 GHz. On wafer test results of the developed 6X harmonic MMIC mixer has substantiated the idler design.

A Novel Design of Slotted Waveguide Phased Array Antenna

M. Elhefnawy, A. A. Al-Hadi — Mon, 10 Jun 2019 11:18:50 -0400

A novel design of phased array antenna based on a Slotted Waveguide Antenna Array (SWAA) is introduced in this paper. The CST Microwave Studio simulation results show that the S‒parameters, the gain, the axial ratio, and the beamwidth of the proposed phased array antenna are affected by the value of the progressive phase shift. The simulated results of the proposed phased array antenna at different values of progressive phase demonstrate that the S‒parameters for almost all ports are less than ‒10 dB over at least 2% bandwidth, the simulated phased array antenna gain is above 17 dB in the frequency range from 9.5 GHz to 9.7 GHz, the range of frequencies over which the simulated Axial Ratio (AR) is below 3 dB is not fixed and varied according to the selected progressive phase, the simulated beamwidth can be 6.5˚ or narrower based on the value of the progressive phase shift.

The Effect of Error Propagation on the Performance of Polar Codes Utilizing Successive Cancellation Decoding Algorithm

O. Gazi, A. A. Andi — Mon, 10 Jun 2019 11:09:32 -0400

In this paper, we discuss and analyze the effect of error propagation on the performance polar codes decoded using the successive cancellation algorithm. We show that error propagation due to erroneous bit decision is a catastrophic issue for the successive cancellation decoding of polar codes. Even a wrong decision on a single bit may cause an abundance of successor bits to be wrongly decoded. Furthermore, we observe that the performance of polar codes is significantly improved if even single bit errors are detected and corrected before the decoding of successor bits.

Analysis of Current Distributions and Radar Cross Sections of Line Source Scattering from Impedance Strip by Fractional Derivative Method

K. Karacuha, E. I. Veliyev, V. Tabatadze, E. Karaçuha — Sun, 09 Jun 2019 16:50:16 -0400

In this paper, we have studied the analysis of current distributions and radar cross sections of line source scattering from impedance strip. The problem was solved with fractional derivative method previously. Here, the specific case of fractional derivative method is investigated. The problem under consideration on the basis of various methods is studied well, however, they are mainly done by numerical methods. The fractional derivative method, allows an analytical solution in a specific situation. This method allows to obtain analytical solution of impedance strip for a special case which is fractional order is equal to 0.5. When fractional order is 0.5, there is an analytical solution which is explained and current distribution, radar cross section and near field patterns are given in this paper. Here, as a first time, current distribution, bi-static radar cross section and near field for the upper and lower part of the strip are studied.