Characteristics Of Radiation Field Research Articles

Microwave Coincidence Imaging with Phase-Coded Stochastic Radiation Field

Microwave coincidence imaging (MCI) represents a novel forward-looking radar imaging method with high-resolution capabilities. Most MCI methods rely on random frequency modulation to generate stochastic radiation fields, which introduces the complexity of radar systems and imposes limitations on imaging quality under noisy conditions. In this paper, microwave coincidence imaging with phase-coded stochastic radiation fields is proposed, which generates spatio-temporally uncorrelated stochastic radiation fields with phase coding. Firstly, the radiation field characteristics are analyzed, and the coding sequences are designed. Then, pulse compression is applied to achieve a one-dimensional range image. Furthermore, an azimuthal imaging model is built, and a reference matrix is derived from the frequency domain. Finally, sparse Bayesian learning (SBL) and alternating direction method of multipliers (ADMM)-based total variation are implemented to reconstruct targets. The methods have better imaging performance at low signal-to-noise ratios (SNRs), as shown by the imaging results and mean square error (MSE) curves. In addition, compared with the SBL and ADMM-based total variation methods based on the direct frequency-domain solution, the proposed method’s computational complexity is reduced, giving it great potential in forward-looking high-resolution scenarios, such as autonomous obstacle avoidance with vehicle-mounted radar and terminal guidance.

Model of occupational exposure of workers performing inspection of welded joints

A model of occupational exposure to gamma flaw detector operators working with portable flaw detectors in the field has been developed. The initial data for the development and verification of the model were the results of measurements of the characteristics of the gamma radiation field at the workplaces of flaw detectors and data from individual dosimetric monitoring. The relationships between the measured (H*(10), Hp(10)) and protection (effective dose) quantities (conversion coefficients) were determined using calculations and phantom experiments simulating three main operations of the full production cycle: transportation of the flaw detector to the place of X-raying of the product, installation of a flaw detector to perform x-raying and X-raying of the product. As a result of the study, it was found that more than 90% of the dose contribution to the readings of an individual dosimeter is due to the installation of the flaw detector in the working position and X-raying of the product. The values of the conversion coefficients for these operations in the form of the ratio of the effective dose values and the readings of dosimeters (Hp(10)) located on the worker's body at chest level (standard place) and abdominal level differ little for both positions of individual dosimeters. The use of maximum conversion coefficient value of 0.8 Sv/Sv corresponding to the operation of X-raying of the product will ensure conservatism in the assessment of the effective dose for the entire production cycle by no more than 15% and 25% for dosimeters located at the chest level and abdominal level, respectively.

About the necessary thickness of stationary shield in X-ray dental rooms

In the paper, based on the analysis of scientific information regarding the parameters and characteris-tics of radiation fields for three dental X-ray procedures (intraoral radiographs, panoramic radiographs on orthopantomographs and computed tomography), the required thickness of stationary shields for rooms with different X-ray equipment is calculated. It has been shown that in most cases, in rooms where intraoral and panoramic radiographs are taken, conventional 20 mm thick plasterboard interior room partitions provide the necessary protection to comply with the dose limit for the population in the adjacent room. For the rooms where dental examinations are carried out using computed tomographs additional lead shield up to 1.5 mm thick is required depending on the conditions and the category of protected persons in the adjacent room.

Simulation research on the characteristics of a minitype neutron reference radiation field

In order to research the characteristics of minitype neutron reference radiation field regulated by ISO 8529 series standards, Monte Carlo simulation method was applied to calculate the ratio of room-scattered neutron response to the direct neutron response, neutron fluence and energy spectra in the radiation field. Firstly, the characteristics of the field were investigated from the four physical factors as shielding materials, field sizes, shielding thicknesses and borated polyethylene with different boron contents. Secondly, the response of sphere instrument with different diameters in the field and the influence of instrument on the field were analyzed. The results showed that minitype neutron reference radiation field with a size of 2 m × 2 m × 2 m, a shielding material of 5 % borated polyethylene and a shielding thickness of 10 cm was expected to be used for the calibration of neutron measuring instrument.

СЛИЧЕНИЕ ДОЗИМЕТРИЧЕСКИХ СИСТЕМ ФОТОННОГО И НЕЙТРОННОГО ИЗЛУЧЕНИЙ, ИСПОЛЬЗУЕМЫХ В ОРГАНИЗАЦИЯХ ГОСКОРПОРАЦИИ «РОСАТОМ» ДЛЯ КОНТРОЛЯ В СИТУАЦИИ ПЛАНИРУЕМОГО ОБЛУЧЕНИЯ

Purpose: Using the example of reviewing and discussing the results of comparison tests of dosimetric systems of gamma and neutron radiation used in organizations of the State Corporation “Rosatom”, to assess the current state of reliability of monitoring the planned exposure of workers in fields of mixed gamma-neutron radiation using the considered dosimetric systems in order to produce recommendations for corrective actions to ensure a unified approach to conduct individual dosimetric control of external exposure. Results: All measuring instruments for individual dose equivalent of photon and neutron radiation, presented in comparison tests, comply with up-to-date requirements for individual dosimetric control systems. All measuring instruments confirmed their measuring capabilities, showed satisfactory quality of measurement results and the absence of a systematic bias in the measurement results. Analysis of the results of measuring the individual dose equivalent of neutron radiation showed that problems affecting the quality of the results obtained were identified in the considered instruments of measuring personal dose equivalent. The following factors might be the sources of problems: lack of knowledge about the real characteristics of radiation fields (spectral characteristics, radiation direction, etc.) at workplaces; insufficient research of the method used for measuring neutron radiation under real conditions (technical and metrological characteristics and features of the individual dosimeters used); failure to take into account the weighing coefficients for neutrons of various energies when measuring instruments are calibrated and when real measurements are conducted. Conclusion: It is necessary to organize and conduct investigations of the metrological characteristics of the measuring instrument that are used under conditions typical for a specific radiation object. After finishing these experimental studies, it is recommended to test the methodology with an analysis of the compliance of the accuracy indicators with the requirements of the relevant guidelines. In order to solve the problem of a lack of knowledge about the real characteristics of radiation fields, radiation safety services of organizations are recommended to organize and conduct research aimed at studying such characteristics using radiometric and spectrometric methods, experimental modeling of the process of personnel exposure using anthropomorphic phantoms and determining correction factors for the individual dosimeters used.

Оценка характеристик полей фотонного излучения медицинских линейных ускорителей электронов различных производителей

The article presents an assessment of the characteristics of pulsed photon radiation fields generated by medical linear electron accelerators (or CLINAC for short), namely: Varian Clinac iX, Elekta Infinity, Varian VitalBeam. Their technical characteristics, namely: average radiation energy, pulse duration and repetition rate, ambient dose equivalent rate in a single pulse are studied from the point of view of using a CLINAC as a source of pulsed photon radiation field suitable for calibration of dosimetric equipment. The average photon radiation energy is calculated using Monte Carlo modeling. Measurement of the ambient dose equivalent rate generated by the CLINAC at a given point is performed by the reference dosimeter DKS-AT5350/1. Determination of single pulse duration and pulse repetition rate is performed by direct measurements using the pulsed photon radiation detection unit BDKG-206.

A numerical study on the role of instabilities on multi-wavelength emission signatures of blazar jets

Context. Blazars, a class of active galaxies whose jets are relativistic and collimated flows of plasma directed along the line of sight, are prone to a slew of magnetohydrodynamic (MHD) instabilities. These jets show characteristic multi-wavelength and multi-timescale variabilities. Aims. We aim to study the interplay of radiation and particle acceleration processes in regulating the multi-band emission and variability signatures from blazars. In particular, the goal is to decipher the impact of shocks arising due to MHD instabilities in driving the long-term variable emission signatures from blazars. Methods. To this end, we performed relativistic MHD (RMHD) simulations of a representative section of a blazar jet. The jet was evolved using a hybrid Eulerian-Lagrangian framework to account for radiative losses due to synchrotron process as well as particle acceleration due to shocks. Additionally, we incorporated and validated radiative losses taking into consideration the external Compton (EC) process that is relevant for blazars. We further compared the effects of different radiation mechanisms through numerical simulation of 2D slab jet as a validation test. Finally, we carried out a parametric study to quantify the effect of magnetic fields and external radiation field characteristics by performing 3D simulations of a plasma column. The synthetic light curves and spectral energy distribution (SEDs) were analyzed to qualitatively understand the impact of instability driven shocks. Results. We observed that shocks produced with the evolution of instabilities give rise to flaring signatures in the high-energy band. The impact of such shocks is also evident from the instantaneous flattening of the synchrotron component of the SEDs. At later stages, we observed the transition in X-ray emission from the synchrotron process to that dominated by EC. The inclusion of the EC process also gives rise to γ-ray emission and shows signatures of mild Compton dominance that is typically seen in low-synchrotron peaked blazars.

Comparison of out-of-field normal tissue dose estimates for pencil beam scanning proton therapy: MCNP6, PHITS, and TOPAS

Monte Carlo (MC) methods are considered the gold-standard approach to dose estimation for normal tissues outside the treatment field (out-of-field) in proton therapy. However, the physics of secondary particle production from high-energy protons are uncertain, particularly for secondary neutrons, due to challenges in performing accurate measurements. Instead, various physics models have been developed over the years to reenact these high-energy interactions based on theory. It should thus be acknowledged that MC users must currently accept some unknown uncertainties in out-of-field dose estimates. In the present study, we compared three MC codes (MCNP6, PHITS, and TOPAS) and their available physics models to investigate the variation in out-of-field normal tissue dosimetry for pencil beam scanning proton therapy patients. Total yield and double-differential (energy and angle) production of two major secondary particles, neutrons and gammas, were determined through irradiation of a water phantom at six proton energies (80, 90, 100, 110, 150, and 200 MeV). Out-of-field normal tissue doses were estimated for intracranial irradiations of 1-, 5-, and 15-year-old patients using whole-body computational phantoms. Notably, the total dose estimates for each out-of-field organ varied by approximately 25% across the three codes, independent of its distance from the treatment volume. Dose discrepancies amongst the codes were linked to the utilized physics model, which impacts the characteristics of the secondary radiation field. Using developer-recommended physics, TOPAS produced both the highest neutron and gamma doses to all out-of-field organs from all examined conditions; this was linked to its highest yields of secondary particles and second hardest energy spectra. Subsequent results when using other physics models found reduced yields and energies, resulting in lower dose estimates. Neutron dose estimates were the most impacted by physics model choice, and thus the variation in out-of-field dose estimates may be even larger than 25% when considering biological effectiveness.

Correction of the Contribution of Scattered Photon Radiation to the Ionization Chamber ReadingsDuring X-Ray Radiation Quality Assessment

Reduction of the systematic error when determining the characteristics of the reference X-ray radiation fields is an essential task according to the ISO 4037-1:2019 standard. This task is especially important in dosimetry laboratories when establishing the qualities of reference photon fields. The aim of the study was to develop a method that allows taking into account the contribution of radiation scattered on the filter when determining the half-value layer of the photon field generated by the X-ray unit. Another goal was to reduce the computational cost of determining this contribution.One of the major contributors to the systematic error in measuring the half-value layer is the radiation scattered on the filter material. The standard recommends that this error should be taken into account in the measurement. But it does not provide any methodology that would do this.The study investigated the possibility of reducing the contribution of scattered radiation to the ionization chamber readings when assessing the radiation quality of the X-ray unit by the means of half-value layer. The study utilized the (N, H, L) quality series as reference fields according to ISO 4037-1:2019.Contribution of the scattered radiation to the half-value layer was compensated with the correction coefficients; they were calculated with the FLUKA Monte Carlo software according to the zero-aperture approximation method. Unlike other similar methods, the proposed approach employs kinetic energy released to matter (kerma), to air in this case, as the main value, which, when utilized instead of deposited energy, reduces the program’s runtime several fold.Correctness of the results obtained in this work was verified by comparing the calculated values of the half-value layer with the tabulated ones provided in the ISO 4037-1:2019 standard. The deviation of calculated values from those specified in the standard does not exceed 2 %.Calculation results showed that the error contributed by scattered radiation to the magnitude of the halfvalue layer in direct measurements does not exceed 5 %. The use of the air kerma allowed us to significantly reduce the time for calculating the correction coefficients by the factor of 6–16 times with respect to other methods, depending on the radiation quality series. This made it possible to calculate correction factors for the source-detector distance equal to 2.5 meters.

Visualization of Rotating Machinery Noise Based on Near Field Acoustic Holography

<p>In order to solve the problem of fast identification of the noise source of rotating machinery, the time-space complex envelope model of monopole sound source is studied, and a modulation method of the complex envelope is proposed. A method combining near-field acoustic holography technology and complex envelope information is proposed to reconstruct the sound field and realize the identification of rotating machinery noise sources. Using the overall fluctuation of the signal to identify the noise source of the rotating machinery greatly reduces the amount of calculation, and speeds up the positioning speed while ensuring the positioning accuracy. According to the sound field radiation characteristics of rotating machinery noise, different measurement distances, different sampling points numbers and different reconstruction distances are selected to reconstruct the sound field. The simulation data analysis results show that the near-field acoustic holography technology can still obtain high sound field reconstruction accuracy under the condition of large reconstruction distance, and does not require high sampling points numbers. Using the envelope information extracted by envelope modulation technology to reconstruct the sound field can accurately identify the number and geometric distribution of sound sources. This technology not only speeds up data processing, but also ensures the accuracy of sound field reconstruction.</p> <p> </p>

W-shaped slot-loaded U-shaped low SAR patch antenna for microwave-based malignant tissue detection system

This paper describes a wideband W-shaped slot-loaded solid U-shaped rectangular patch antenna for a microwave-based head imaging application. The proposed antenna comprises a W-shaped slot-loaded solid U-shaped radiating patch and a slotted partial ground. Slots have been used to enhance efficiency, current distribution, gain, and other antenna performances. At its first resonance frequency of 1.6 GHz, the optimized electrical dimension is 0.197λ × 0.298λ × 0.085λ. The antenna is printed on a low-cost 1.6 mm-thick FR4 substrate. The antenna feeds with a 50 Ω transmission line. The assessed findings demonstrated that the stated prototype has a 1.12 GHz (1.40 - 2.52 GHz) bandwidth along with omnidirectional radiation properties. The prototype achieved a maximum gain of 3.5 dBi at 2.44 GHz and provided a maximum radiation efficiency of 95% with stable radiation characteristics. The face-to-face alignment fidelity factor (FF) is also determined to evaluate time-domain responses above 80%. Near field directivity (NFD) is also analyzed with a head model to ensure near field radiation characteristics. The SAR value reaches a < 0.3 W/kg limit over the active bandwidth. Finally, in a CST simulation platform, an array configuration with nine antenna elements is deployed in a circular arrangement around the head phantom to collect the scattered data for tumor object characterization.

Additively Manufactured Amplitude Tapered Slotted Waveguide Array Antenna With Horn Aperture for 77 GHz

In this work, a combined frontend of horn and slotted waveguide array antenna serving as feeding subsystem is presented. This setup allows to implement an amplitude taper in one plane while using the horn aperture to shape the far field radiation characteristics in the perpendicular plane independently and tailored to the individual demand of the application. Moreover, the feeding system is implemented as a loop resulting in a standing wave distribution for a wide frequency range in order to increase the antenna bandwidth. Two specimens with different horn apertures are additively manufactured in slotted waveguide technology from UV curable photopolymer resin using a digital light processing 3D printer and subsequently metal coated by electroless silver plating. A relatively large bandwidth of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{B}_{-10\text {dB}} = 7.2$ </tex-math></inline-formula> GHz and a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{B}_{-15\,\text {dB}}$ </tex-math></inline-formula> of 4.9 GHz is achieved in measurements indicating a relative bandwidth of 9 % and 6 % respectively. Antenna Gain is characterized as 17.5 and 20.17 dBi in measurements while maintaining a sidelobe level of 20–22.5 dB at 77 GHz and exhibiting a radiation efficiency of 78.9 and 79.4 %. The proposed antenna architecture provides a flexible approach for beam shaping in applications where azimuth and elevation planes exhibit different or contrary requirements, e.g. broad vs. narrow field of view - especially suitable for automotive MIMO-radar sensors.

Stray radiation produced in FLASH electron beams characterized by the MiniPIX Timepix3 Flex detector

This work aims to characterize ultra-high dose rate pulses (UHDpulse) electron beams using the hybrid semiconductor pixel detector. The Timepix3 (TPX3) ASIC chip was used to measure the composition, spatial, time, and spectral characteristics of the secondary radiation fields from pulsed 15–23 MeV electron beams. The challenge is to develop a single compact detector that could extract spectrometric and dosimetric information on such high flux short-pulsed fields. For secondary beam measurements, PMMA plates of 1 and 8 cm thickness were placed in front of the electron beam, with a pulse duration of 3.5 µs. Timepix3 detectors with silicon sensors of 100 and 500 µm thickness were placed on a shifting stage allowing for data acquisition at various lateral positions to the beam axis. The use of the detector in FLEXI configuration enables suitable measurements in-situ and minimal self-shielding. Preliminary results highlight both the technique and the detector’s ability to measure individual UHDpulses of electron beams delivered in short pulses. In addition, the use of the two signal chains per-pixel enables the estimation of particle flux and the scattered dose rates (DRs) at various distances from the beam core, in mixed radiation fields.

Characteristics of HEMP Radiation Field on Typical Transport Aircraft with Frequency Sweep Method

This paper presents characteristics of the HEMP radiation field on a typical transport aircraft using the frequency sweep method. Firstly, the characteristics of the HEMP field are analyzed. Then, various parameters including the electric field strength and magnetic field strength distribution are calculated using Altair FEKO software. Afterwards, the electric field strength distributions of three layers (top layer, inner layer and bottom layer) are calculated and analyzed. The results indicate that the HEMP induced field is affected by the aircraft body. The induced electric field strength E(t) varies greatly at different positions. Nevertheless, the peak value of E(t) is usually greater than the initial peak value of electric field strength E0. Such a study can provide guidance and insight into the protection design of the HEMP of the aircraft.

Оптимізація часу і статистичної похибки розрахунку біологічного захисту контейнерів зберігання відпрацьованого ядерного палива

The radiation protection is an important issue in the operation of nuclear power plants and artificial radioactive sources, which include spent nuclear fuel storage facilities. The Monte-Carlo codes are the effective instruments for calculation of radiation shielding properties and radiation field characteristics for complex geometries. However, achieving a satisfactory statistical error of the results in modeling the passage of neutrons and photons through biological protection may require excessively long calculation time. To solve this problem, Monte-Carlo codes use methods to reduce the variance to direct particles to regions with detectors to improve statistical accuracy. Our paper presents the application of the variance reduction function based on weight windows in the Monte-Carlo Serpent code, the function is investigated on the example of a simplified 2D model of the spent nuclear fuel storage container HI-STORM 190. The simple approach option of variance reduction with fixed cartesian and cylindrical meshes was investigated for different mesh nodes and for different dimensions of nodes. Also, global variance reduction option with fixed cartesian and cylindrical meshes was analyzed for case of achieving satisfactory results for the entire simulated volume. For a qualitative assessment of the variance reduction function, the indicator — figure of merit (FOM) used in our paper which proposed by the developers of the Serpent Monte-Carlo code. It is shown that the use of the variance reduction function leads to a significant decrease of statistical error and decrease of the calculation time, and therefore can be useful for biological protection calculations. As conclusions we can note that: the cylindrical mesh is not as effective in terms of FOM compared to Cartesian mesh; for both cylindrical and Cartesian meshes it is possible to find the recommended grain (node) size; the use of azimuthal partition of the cylindrical mesh together with radial partition leads to an increase in FOM; the application of global variance reduction is useful in the case of asymmetric biological protection geometries, while the FOM decreases.

APPLICATION OF POSITION-SENSITIVE DETECTORS FOR ANALYZING THE ENERGY SPECTRA OF PHOTON RADIATION

Monitoring the spectral composition of photon radiation from generating sources and emitting objects is the most informative way to analyze the radiation fields created by them. However, it is impossible to study the radiation characteristics of radiation fields of ultra short duration and high intensity using direct measurement methods. This work considers a method for reconstructing the spectral distributions of photon radiation from the profile of the secondary radiation fields recorded by a position-sensitive detector. To implement a new method of measurement in the primary beam of radiation is an extended scattering body of homogeneous material. Outside the field of the primary beam, a position-sensitive detector is placed along the generatrix of the scattering body, which records the photons of the secondary radiation and the coordinates of their emission. The spectral composition of the primary radiation beam is restored from the shape of the spatial distribution obtained. To find a quasi-solution describing the energy spectrum of the primary radiation beam, it is proposed to use the maximum likelihood expectation maximization method. The possibility of switching to measurements in secondary radiation fields having a lower intensity is confirmed by the experimental results. To form secondary radiation fields, we used a composite phantom containing three scattering bodies in the form of rectangular parallelepipeds made of graphite, aluminum, and titanium. The secondary radiation fields were recorded by a radiographic sensor. Using an X-ray source operating in a pulsed mode, images were obtained and profiles of the secondary radiation fields were formed. It is experimentally shown that the secondary radiation fields have a gradient structure and can be used to analyze the energy spectra of the radiation beams generating them. The method for reconstructing spectral distributions proposed in this work allows one to measure the energy spectra of photons using position-sensitive detectors and can be used in solving problems of diagnostics of pulsed high-intensity radiation beams.

Characteristics of Photon Radiation Fields in Iron for Photon Sources with Energies from 10 to 50 MeV

Based on the results of Monte Carlo calculations of the spatial energy distributions of photons in iron from point isotropic and planar mononirectional monoenergy sources with energies of 10-50 MeV, the air Kerma attenuation multiplicities and dose accumulation factors of the material under consideration are determined.. The calculations take into account the contribution of the fluorescence, annihilation radiation and bremsstrahlung. The independence of the accumulation factors from the angular distribution of the source radiation is shown, and the independence of the attenuation multiplicities from the angular distribution of the source radiation and the weak dependence on its energy in the energy range 30-50 MeV is also shown. The corrections for the barrier protection are determined and their independence from the thickness of the protection and the photon energy of the source is noted. The obtained information allows to reduce the errors of the results of calculations of the thickness of anti-radiation protection of electronic accelerators at high energies, using developed engineering methods of calculation. The obtained information can also be used in calculations of protection against brake radiation of electronic accelerators by engineering methods.

Higher-order harmonic generation of laser radiation due to relativistic plasma resonance at nonrelativistic laser intensity

The well-known plasma resonance (transformation into plasma waves) at a critical density in an inhomogeneous plasma easily becomes relativistic nonlinear even at nonrelativistic laser intensities because the generated electrostatic field is significantly increased. Therefore, the widely used theory of harmonic generation by plasma resonance in a laser-produced plasma should be re-examined. We formulate the corresponding analytical theory of higher-order harmonic generation by nonrelativistic intense laser radiation propagating in a spatially inhomogeneous plasma. We find the spectral and angular characteristics of the harmonic radiation field and demonstrate the role of relativistic nonlinearity at plasma resonance in forming the harmonic spectra. The applicability range of the developed theory is determined by the plasma wave-breaking condition in the vicinity of the critical plasma density, which we analyze explicitly. The proposed theory is compared with the standard perturbation approach. Because the latter corresponds to low laser intensities, this comparison clearly shows the failure of the theory of harmonic generation via linear plasma resonance. The presented relativistic theory, which is applicable up to the laser intensity corresponding to plasma wave breaking, demonstrates the formation of a smooth power-law energy spectrum of higher-order laser harmonics in contrast to the standard perturbation theory. A spectral modulation of harmonics is also shown, which is a unique feature of relativistic nonlinearity.

A High Channel Consistency Subarray of Plane-Wave Generators for 5G Base Station OTA Testing

A high channel consistency subarray of plane-wave generators (PWG) is described for fifth-generation (5G) base station (BS) over-the-air (OTA) testing. Firstly, the variation of the near field radiation characteristics of the subarray based on the feed amplitude and phase errors of the traditional power divider network is analyzed. The recommended amplitude and phase errors between channels are given. After that, a novel subarray which combines four pyramidal horn antennas and a compact 1:4 waveguide power divider is designed. The optimized perfectly symmetrical zigzag waveguide transmission lines are used to realize consistent power allocation among antenna elements. No intermediate pins are employed, which avoids the significant deterioration of channel consistency caused by assembly errors. The size of the subarray is 4.89 λ0 × 4.97 λ0 × 1.23 λ0 (λ0 is the working wavelength corresponding to the subarray center frequency at 3.5 GHz). The VSWR &lt; 1.5 impedance bandwidth covers 3.4 GHz to 3.6 GHz. The amplitude difference between the four elements of the subarray is less than 0.5 dB, and the phase difference is less than 3°. The simulated and measured results agree well in this design.

Design of compact microstrip patch antenna for WBAN applications at ISM 2.4 GHz

This paper introduces the design of compact microstrip patch antenna for wireless body area network (WBAN) applications at ISM 2.4 GHz. The design consists of a radiating patch on one side of the substrate and a ground plane is located on the other side of the substrate. The antenna is fed through an inset transmission line and then loaded by two triangles, and shorting pins on both sides of the radiating patch to lengthen the path for current, as result it reduced the overall size. The dimensions of radiating patch antenna are 62 mm&lt;em&gt;× &lt;/em&gt;43 mm &lt;em&gt;× &lt;/em&gt;1.67 mm. By locating the proposed antenna On and Off body communication, it can maintain compact and stable far field radiation characteristics and negligible specific absorption rate (SAR). Furthermore, high efficiencies of about 53 % and 46% are obtained during off and on body, which is higher than recent similar works in the literature. The simulated results showed a good agreement with the measured results. Owing to the acceptable results, the proposed design can be a reliable candidate for WBAN applications at ISM band.