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Hyperthermia plays an important role in the treatment of cancer. A circular ring slot patch antenna for Hyperthermia applications is presented at 2.45 GHz. The proposed antenna shows return loss without significant detuning or impedance mismatch with different positions concerning a phantom muscle model. The simulation study is done by a Finite Element Method (FEM) based on Ansoft’s HFSS software. The antenna penetration depth, return loss, and the specific absorption rate (SAR) pattern are evaluated for various antenna orientations concerning the phantom muscle model.

In this paper, theoretical/simulation study of specific absorption rate (SAR) and/or temperature distributions in a bi-layered bio-media (fat and muscle)/realistic tri-layered bio-media (skin, fat, and muscle layers) in direct contact with water-loaded metal diagonal horn (MDH) designed at 915 MHz are investigated. The effects of fat thickness on the input reflection coefficient, reflection coefficient at the interface between the MDH and the bi-layered bio-media, and the SAR distribution in the bi-layered bio-media are also studied through simulation and theoretically at 915 MHz. Further, the SAR parameters such as penetration depth and effective field size inside the bi-layered bio-media due to the MDH are evaluated theoretically and the theoretical results are compared with the corresponding simulation results. Finally, SAR and temperature distributions in tri-layered bio-media without and with embedded irregular/oval-shaped tumor are provided for demonstrating the hyperthermia performance of the MDH applicator.

A super-compact ultra-wideband (UWB) microstrip band-pass filter (BPF) with good selectivity and wide stopband is proposed in this paper. The super-compactness along with wide stopband of the proposed filter is achieved by integrating modified multimode resonator-based UWB BPF and defected ground structure (DGS)-based compact low-pass filter (LPF). The LPF structure is designed using four non-uniform configurations of DGS units along with a 50 Ω microstrip line. Each DGS unit is formed by cascading three isosceles U-shaped DGSs. Further, an equivalent RLC circuit model of the LPF is proposed to validate the numerical simulation and experimental results of LPF. The proposed filter has simulated passband frequency range 3–11 GHz with wide stopband: attenuation better than 40 dB and 25 dB over the frequency ranges 11.7–20.5 GHz and 11.2–30 GHz respectively. The experimental results for the proposed filter are nearly in agreement with corresponding numerical simulation results.

A compact, conformal applicator having good impedance matching over various loaded conditions with minimum leakage radiation is desirable for hyperthermia treatment of cancer. Hence, in this paper, a new compact conformal multilayer slot antenna with embedded water bolus terminated in muscle medium is presented for hyperthermia application. A simple $50 \Omega$ microstrip line with fork-shaped tuning stub is used to excite the proposed conformal antenna. The antenna input reflection coefficient and hyperthermia assurance parameters viz. effective field size, depth at $\Delta\mathrm{T} /2$ and heating area in the tissue medium are evaluated for different antenna curvature at 2.45 GHz (curvature of the applicator is identical to the bio-model). The simulation results for the proposed antenna show a reduced tissue surface heating and back field irradiation.

This paper describes simulation and/or experimental studies of specific absorption rate (SAR) and temperature distributions in a biological phantom (muscle)/realistic tri-layered bio-media without and with oval-/irregular-shaped tumour in direct contact with hybrid mode (water-loaded) metal-dielectric wall diagonal horn designed at 2450 and 915 MHz and their comparison among themselves with those due to respective conventional metal diagonal horns. The diagonal horns reported in this paper provide simple and effective means to enhance the penetration depth in the bio-medium/media. Moreover, effects on penetration depth and effective field size due to presence of oval- and irregular-shaped tumours in the tri-layered bio-media are also investigated at 915 MHz. It is demonstrated that desired temperature range 41 °C–45 °C can be achieved and maintained for 60 minutes with input power of 9 W at the frequency of 915 MHz for treating tumours at relatively greater depth.

This paper describes simulation, theoretical, and/or experimental studies of specific absorption rate (SAR) distribution in biological phantom (muscle)/tri-layered bio-media without and with irregular-shaped tumors in direct contact with improved water-loaded metal diagonal horns designed at 2450 and 915 MHz. Further, thermal simulation results based on Pennes’ bio-heat equation are also provided for each of the proposed applicators, which is in direct contact with realistic tri-layered bio-media without and with irregular-shaped tumor embedded within the muscle layer. The proposed horns are improved versions of the respective conventional metal diagonal horns in which the aperture fields, which are modified by introducing four conducting pins at appropriate locations near each antenna aperture, correspond to fundamental and higher order modes. The theoretical aperture field distributions of the proposed horns designed at 2450 and 915 MHz are compared with the corresponding simulated ones. Further...

This paper presents the simulation and experimental studies of a conformal microstrip slot antenna integrated with artificial magnetic conductor (AMC) for hyperthermia application. In the proposed applicator, an AMC consisting of an array of modified ring patches on a grounded dielectric substrate is located at optimized distance (=4 mm) from the microstrip slot antenna for improved performance of the applicator. The feed configuration of the proposed slot antenna consists of tapered microstrip line with curved tuning stub. The slot and feed configurations of the antenna are modified to widen its bandwidth so that changes in dielectric property of biological phantom medium can have minimal effect on its operating frequency and impedance bandwidth. In addition, the applicator with modified slot and feed arrangement provides enhanced heating depth in the phantom muscle medium. Provision for cooling of tissue surface is made by providing air gap between the slot antenna and phantom muscle medium. Mor...

This study presents the design of water-loaded metal diagonal horn antenna at 2450 MHz along with simulation and experimental studies of specific absorption rate (SAR) and temperature distributions in a bio-medium (muscle) in direct contact with the water-loaded antenna for hyperthermia application. The metal diagonal horn is a multimode horn antenna, with identical aperture field distribution in the E- and H-planes. The SAR distribution in a phantom muscle in direct contact with water-loaded horn antenna measured at 2450 MHz is nearly in agreement with the corresponding simulated distribution. The simulation results for SAR distribution owing to diagonal horn are also compared with those owing to square aperture horn/box horn, of same aperture cross-section/broader dimension as the diagonal horn at 2450 MHz. The results indicate that the diagonal horn provides higher penetration depth/better transverse resolution over square aperture horn/box horn. In addition, the proposed diagonal horn provides circularly symmetric effective field size. Finally, thermal simulation results are also provided for the proposed applicator, which is in direct contact with a realistic model of muscle medium without and with small spherical as well as oval-shaped tumours of different dielectric properties embedded within the muscle medium.

Comparative simulation study of dual segment cylindrical dielectric resonator antenna (CDRA) with different feed configuration is described in the present investigation. The antenna consists of dielectric ceramic (e r = 17) as lower segment and Teflon (e r = 2.1) as upper segment. The reflection coefficient — frequency characteristics and radiation pattern of the proposed CDRA are investigated through simulation using Ansys HFSS software. The proposed antenna provides simulated input impedance bandwidth of 3.75 GHz over the frequency range 7.77 GHz–11.52 GHz (percentage bandwidth of 38.8 %) with simulated peak gain of 3.54 dB at 8.11 GHz. The antenna provides omni directional radiation patterns in E- and H-planes with fairly low cross-polarization level. Such CDRA can potentially use in radar and satellite communication as a primary feed.

This paper is a continuation of our previous published work in which a water-loaded metal diagonal horn antenna has been designed at 2450 MHz for hyperthermia application and simulated results are compared with those measured. In the present study, theoretical investigations of Specific Absorption Rate (SAR) distribution in a homogeneous biological phantom (muscle) due to direct contact water-loaded metal diagonal horn antenna at 915 and 2450 MHz for hyperthermia application is presented. It is estimated theoretically that, at both the operating frequencies, a reasonable impedance matching is achieved at the interface between the antenna aperture and the biological phantom, where a computation of aperture admittance and reflection coefficient has been performed. Furthermore, it is confirmed through theoretical and simulation studies that the proposed horn antenna gives circularly symmetric SAR distribution in transverse plane in the biological phantom at 915 and 2450 MHz. The simulated and theoretical SAR distributions at 2450 MHz are compared with those determined at 915 MHz. In addition, thermal simulation results based on Pennes' Bio-heat equation (BHE) are applied to the realistic muscle model at 915 and 2450 MHz. The reduction of blood flow rate on temperature distribution is also studied.

In this paper, a compact lowpass filter (LPF) with wide stopband is reported which uses four non-uniform cascaded defected ground structure (DGS) units along with a 50 Ω microstrip line. Each DGS unit is formed by combining three isosceles U-shaped DGSs and provides three attenuation poles. The proposed LPF has size of 14.44 mm × 3.4 mm, 3-dB cut-off frequency of 14.2 GHz, and greater than 40 dB and 22 dB stopband rejection upto 21.8 GHz and 30 GHz respectively. The proposed LPF is fabricated and experimentally tested. The experimental results are nearly in agreement with corresponding numerical simulation results.

In this paper, an ultra-compact Ultra-wideband (UWB) bandpass filter (BPF) based on modified multimode resonator (MMR) is proposed. The compactness of the proposed UWB BPF with good impedance matching in passband is achieved using modified MMR, which consists of meandered coupled lines, stepped-impedance stubs, open-circuited stubs and coupled-line sections. Stepped-impedance stubs which are used to nullify the effect of mutual coupling due to the presence of meandered coupled lines are analyzed in detail. The proposed filter is fabricated using Roger RT/duroid 5880 substrate (∊ r = 2.2, thickness = 0.787 mm) having size of 14 mm × 5.9 mm. The experimental results show that the proposed filter has passband frequency range 3.05–10.9 GHz with upper wide stopband attenuation better than 38 dB up to 15.5 GHz. The simulation results are nearly in agreement with corresponding experimental results.

This paper examines the influence of water bolus coupling layer on the specific absorption rate and temperature distributions respectively in the tissue during hyperthermia treatment of human limb tumor using a previously reported microstrip slot antenna integrated with a compact artificial magnetic conductor (AMC) reflector at 2.45 GHz. The simulation study reveals the effectiveness of the antenna-AMC combination for hyperthermia treatment of arm and thigh tumors. Further, the results indicate that during treatment, hotspot in the skin can be reduced by optimizing water bolus temperature.

This article depicts the processing and mechanical characterization of a new class of multi-phase composites consisting of epoxy resin reinforced with jute fiber and filled with silicon carbide (SiC) particulates. The SiC used as filler material in this work was prepared from rice husk through plasma-processing technique. The effect of filler in modifying the physical and mechanical properties of jute—epoxy composites has been studied. It is found that the incorporation of rice husk derived SiC modifies the tensile, flexural, and inter-laminar shear strengths of the jute—epoxy composites. The micro-hardness and density of the composites are also greatly influenced by the content of these fillers.

A filleted rectangular dielectric resonator antenna (FRDRA) is described in this paper. The antenna consists of Teflon (er = 2.1) as lower segment and 10 wt% of glass (PbOBaO-B2O3-SiO2) sintered Barium Strontium Titanate (BST) namely BSTG10 (er = 27) as upper segment. Glass was added to lower the sintering temperature from 1050 °C to 800 °C and increase the permittivity of BST. The FRDRA provides the simulated input impedance bandwidth of 4.85 GHz (7.71 – 12.56 GHz) that is an improvement in bandwidth of ∼ 33 % as compared with the conventional dual segment rectangular dielectric resonator antenna. Filleted design also offers the advantage of minimum material requirement. Stable radiation pattern of the proposed antenna throughout its whole bandwidth is obtained. Aperture coupled feed mechanism is used due to its advantage of provide no spurious radiation in contrast to the characteristic of probe feed.

A compact aperture-coupled dual segment rectangular dielectric resonator antenna (ACDS-RDRA) is described in this paper. The antenna consists of Teflon (er = 2.1) as lower segment and liquid phase (glass) sintered Barium Strontium Titanate (BST) namely Ba0.5Sr0.5TiO3 (er = 27) as upper segment. 10 wt% of PbO-BaO-B2O3-SiO2 glass was added to lower the sintering temperature from 1050 °C to 800 °C and increase the dielectric constant of BST. The input and radiation characteristics of ACDS-RDRA are investigated through simulation using Ansys HFSS software. The antenna provides the simulated input impedance bandwidth of 690 MHz (8.80 – 9.49 GHz) with a simulated peak gain of 6.63 dB at 9.1 GHz. The antenna provides broadside radiation patterns in both E-and H-planes of the antenna with fairly low cross-polarization levels in E-plane were obtained. Such RDRA can find potential applications in radar and satellite communication.

In this paper, a modified microstrip interdigital bandpass filter (IBPF) with a pair of spurlines and defected ground structure (DGS) containing stepped impedance resonator (SIR) is proposed. A combination of spurlines and SIR-shaped DGS is used to obtain wide stopband which is the result of band notched characteristics of spurline and harmonics suppression characteristics of DGS. The 3-dB impedance bandwidth of the proposed filter is 1.153 GHz (79%) and covers the frequency range 0.885–2.038 GHz. The proposed filter is compact having size of 0.107 λ0 × 0.075 λ0, where λ0 is the free space wavelength at the centre frequency (f0) of 1.46 GHz. The compact, wideband BPF with wide stopband has stopband attenuation better than 14 dB upto the frequency range of approximately six times the centre frequency of the desired passband. The insertion loss value of the proposed filter varies from 0.12–0.57 dB over its operating frequency band.

In this paper, design of a microstrip slot antenna for hyperthermia application is presented. A simple 50-Ω microstrip line is used to excite the proposed antenna. The antenna input reflection coefficient, Specific Absorption Rate (SAR) distribution in the phantom muscle medium and the related parameters viz. penetration depth and Effective Field Size (EFS) were determined at 2.45 GHz. Further, the results obtained using the proposed antenna is compared with those determined using conventional patch antenna. The results indicate that the proposed antenna provides higher penetration depth and smaller EFS over the conventional patch antenna. In addition, the proposed antenna is compact and its behavior is more stable in terms of frequency with change in dielectric properties of muscle medium as compared with the conventional patch antenna.

In this paper, simulation study of a water-loaded metal-dielectric diagonal horn antenna in direct contact with phantom bio-medium (muscle) is presented. The proposed antenna is a new type of diagonal horn in which the major portion of the antenna walls is made of Lucite while remaining wall portion is made of metal, considering the region of the antenna from throat to aperture. The field over the aperture of the metal-dielectric diagonal horn corresponds to combination of a number of hybrid modes. The SAR and temperature distributions in the muscle-medium along with antenna input reflection coefficient and aperture electric field distribution across the antenna aperture were determined at 2.45 GHz and the results are compared with those due to the conventional metal diagonal horn of same aperture dimensions.

This paper investigates TiO2 loaded metal diagonal and square horn antennas and specific absorption rate (SAR) distributions in a phantom bio-medium due to these antennas through simulation. Diagonal horn is a multimode horn antenna whereas in conventional square horn only TE10 mode propagates. Both diagonal and square horns, which are terminated in a phantom bio-medium are designed and simulated at 2.45 GHz using FEM based Ansoft's HFSS software. The SAR distributions in the bio-medium due to diagonal and square horns are compared at 2.45 GHz.

This paper presents the design and optimization of a probe-fed tri-band C-shaped slot loaded microstrip antenna that can operate in three frequency bands. The proposed antenna operating in the three frequency bands (3.50-3.60 GHz, 4.88-5.23 GHz and 6.46-6.70 GHz) with corresponding resonant frequencies of 3.55 GHz, 5.0 GHz and 6.57 GHz is designed and optimized using FEM based Ansoft HFSS software. By altering the dimensions of C-shaped slot, conventional dual band characteristics can be modified to a triple band characteristics which can support WLAN communication coverage IEEE 802.11j (4.90-5.091 GHz) and others. The proposed antenna features omni-directional characteristics over 3.50-3.60 GHz range and highly directional radiation pattern over 6.46-6.70 GHz range which are used for navigation and remote sensing respectively.

This paper presents the simulation study of specific absorption rate (SAR) distribution in a phantom muscle medium due to TiO2 loaded metal diagonal horn antenna. Diagonal horn is a multimode horn antenna in which the internal fields consist of a superposition of the orthogonal TE10 and TE01 modes in square waveguide. In diagonal horn, excited electric field is parallel to one of its diagonals, causing diagonal polarization of the aperture field. The metal diagonal horn is filled with titanium dioxide (TiO2) to provide good impedance match between the horn and phantom muscle medium (er = 47.5, tanδ = 0.28421, δ = 1.838 S/m). Metal diagonal horn is designed and simulated at 2.45 GHz using FEM based Ansoft HFSS software for hyperthermia applications. The antenna return loss, distribution of electric fields within the antenna structure, and the SAR distribution in the bio-medium due to the antenna are determined at 2.45 GHz.

In this paper performance of planar trapezoidal toothed log-periodic antenna on different dielectric substrates through simulation using FEM based Ansoft HFSS software has been presented. This antenna is a type of frequency independent antenna. The performance characteristics of the proposed antennas formed by providing definite conducting pattern characterizing the antenna on different substrate materials (Bakelite (er = 4.8, tanδ = 0.002), FR4_epoxy (er = 4.4, tane = 0.02), Arlon25FR (er =3.43, tane = 0.0035) and Teflon (er = 2.08, tane = 0.001)) having thickness of 1.6 mm as well as metal antenna without substrate material are studied. It is observed from the study that antenna on Teflon substrate provides widest bandwidth among all the substrate antennas. Further, the performance of antenna on Teflon substrate is almost similar to metal antenna without substrate.

The effect of absorbed microwave power in water on germination of some fungal spores was seen. Water samples were exposed to 2.71 GHz microwave at varying incident power density. Incident and absorbed power by water were determined using power sensor and meter. Germination responses of different fungal spores taken from fresh cultures were studied in the microwave power-absorbed-water samples. The study revealed differential germination responses with variation of the absorbed microwave power in water on different fungi. Results indicated that water has the capability to store microwave power alterations.

A wideband (4.94-6.959 GHz) four element rectangular dielectric resonator antenna array has been designed for 5.0 GHz WLAN and WiMAX band and its radiation characteristics determined through simulation studies using CST Microwave Studio software. Further, simulation results for power absorption in a homogenous bio-medium (muscle layer) in direct contact with the proposed antenna array is presented in terms of specific absorption rate (SAR) distribution in the medium.