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Електромагнітна енергія може змінювати метаболічні і біосинтетичні процеси при певних параметрах імпульсного ЕМП (частота прямування імпульсів, шпаруватість, потужність, експозиція) може уповільнювати і пригнічувати клітинний ріст. Опромінювання в ММ діапазоні РНК і ДНК, що містить вірус приводить до зниження їх інфекційності. Пригнічення роста культур бактерій, зміна фагоцитарної активності, біосинтезу білків, ультраструктурні зміни в клітинах при взаємодії ЕМП КВЧ діапазону. В дослідженнях з мікроорганізмами було встановлено, що біологічний ефект від дії ЕМП на мікроорганізми носив резонансний характер. В якості одного з основних механізмів гнітючої дії КВЧ випромінювання на шкідливі мікроорганізми є роль біологічних мембран в реакціях мікроорганізмів на ЕМВ. Електричні явища, які проходять в біомембранах, відіграють виключно важливу роль. Утворення трансмембранної різниці потенціалів обумовлено виборчої іонною провідністю мембран в цілому, є відмінним діелектриком, так біошари електроізолюючих ліпідних молекул здатні витримувати напруженість ЕП порядку 105 В/см. Величина електричного потенціалу на мембрані вкрай важлива. За сучасною теорією трансмембранного транспорту, а саме ЕП всередині мембрани складає потоки необхідних речовин із навколишнього середовища всередину клітини та з клітини в навколишнє середовище через спеціальні гідрофільні канали, скоріше всього, ліпопротеїнової природи. Швидкість проникнення іонів через мембрану визначається такими властивостями, як товщина, значення ДП, наявність фіксованих електричних зарядів на мембрані, розміри і число пор в мембрані, наявність фіксованих зарядів в порах та деякими іншими.

Ideja za izdelavo magistrske naloge se je pojavila s potrebo postavitve lastnega laboratorija za elektromagnetno združljivost (angl. Electromagnetic compatibility – EMC) v podjetju Instrumentation Technologies d.o.o. za namene testiranj skladnosti naprav s standardi elektromagnetne združljivosti. Vsaka električna naprava med svojim delovanjem oddaja elektromagnetno valovanje oz. lahko na njeno delovanje vpliva elektromagnetno valovanje drugih naprav. Da se električna naprava sme prodajati, mora zadostiti mejam, ki jih določajo standardi elektromagnetne združljivosti naprav. Testiranje električnih naprav se mora izvajati v nadzorovanem okolju z umerjenimi inštrumenti, za katere potrebujemo naprave za umerjanje. Ena od takšnih pomembnih naprav za umerjanje je lahko generator radio-frekvenčnega (RF) glavnika, katerega spektralne komponente so številski mnogokratniki osnovnega signala, ki so poznani tako po frekvenci kot amplitudi. Tak frekvenčni glavnik omogoča ovrednotenje meritev elektromagnetnih motenj same merilnice ali okoljskih vplivov. Izmerjeno sevanje radio-frekvenčnega glavnika predstavlja referenco, ki se upošteva pri meritvah testiranih naprav. Ko želimo izmeriti sevanje same naprave s pomočjo radio-frekvenčnega glavnika, najprej pomerimo umetno (referenčno) sevanje ter tako spoznamo okolje in nato še sevanje testirane naprave. Zgrajen radio-frekvenčni glavnik generira spekter signala med 10 MHz in 1 GHz z dvema možnima korakoma spektralnih komponent, 10 MHz ali 100 MHz. Izbira željenega koraka je mogoča med samim delovanjem naprave. The idea for the master dissertation appeared with the need for the laboratory of electromagnetic compatibility (EMC) in the company Instrumentation Technologies d.o.o with the purpose of testing the compliance of electronic devices with the standards of electromagnetic compatibility. Every electric device during the operation produces electromagnetic radiation and also can be affected by the electromagnetic radiation from other devices. That the electric device can be sold on the market should suffice with the limits provided by the electromagnetic compatibility standards. Electric device testing must be performed in a controlled environment with calibrated instruments. To ensure a controlled environment, a device for calibration is needed. One such device is a radio-frequency comb generator - COMB. Spectral components of the COMB generator are numerical multiples of the original signal, in which frequency and amplitude are known. The COMB generator device is used to evaluate the measurements of the electromagnetic disturbances of the measuring chamber or the environmental disturbances. COMB generator radiation is used as a reference during the measuring of the electromagnetic disturbances of the testing devices. Before the radiation of the device tested is measured, the COMB radiation is measured which gives us the knowledge of the environmental influences – reference radiation, and after that, the device tested is measured. A Radio-frequency comb generator generates the spectrum of the signal between 10 MHz and 1 GHz with two possible steps between the spectral components, 10 MHz or 100 MHz. Step between the signal spectrum components could be selected during the device operation.

A unique micro-metamaterial antenna for light and microwave wavelength conversion is proposed, where the antenna has the form of a panda ring which consists of the mu negative metamaterial silver bars embedded at the microring center. The micro-metamaterial antenna characteristics are investigated, where the antenna resonance frequency and frequency range of 1.60 THz and 1–2.2 THz are achieved. The radiation pattern of the micro-metamaterial antenna is plotted, where the obtained gain and directivity of the antenna are − 8.13 dB. The optimum antenna radiation efficiency is 1 when the antenna has dissipative loss is neglected. The micro-metamaterial antenna can be used as a converter between light and microwave, which is useful for a wavelength converter device.

The human body’s absorption of electromagnetic fields from communication enabled devices has consistently been a research topic for both researchers from universities and companies in the mobile communication industry. The absorption of electromagnetic fields could mainly result in two consequences: (a) antenna radiation efficiency of the device could deteriorate dramatically; and (b) a large amount of the radiated power could be dissipated into the human body, such as the hand, ear, scalp and brain, which is defined and described by Specific Absorption Rate (SAR). A comprehensive analysis of electromagnetic field absorption by the human body has been carried out to explain and answer some of the key questions in this area.

The scattered fields of antennas can be decomposed into two terms; one depends only on the structure of the antenna while the other depends on the antenna radiation parameters and the loading conditions. This decomposition is used to investigate the antenna radar cross section (RCS) behavior with variable loadings. Then, a general analytical load condition for zero or minimum bistastic radar cross section is derived. The derived formula is used to obtain the regions of feasible passive loads for zero backscattering for three different antenna structures. The backscattering levels of these antennas are examined to validate this formula. The results demonstrate the validity of the procedure with almost zero backscattering for all structures with evident RCS reduction factors.

This paper proposes a simple and efficient technique to improve the antenna radiation performance in stacked printed circuit boards (PCBs) for Internet-of-Things (IoT) applications. In the ...

In this article, tunable integrated filter/antennas are demonstrated with two coupling configurations that provide design control of the bandwidth performance over the tuning range. The first is a single-layer third-order tunable filter/antenna with an increasing fractional bandwidth (FBW). The measured device has a frequency tuning range from 1.62 to 2.08 GHz, an FBW increasing from 3.0% to 4.8%, and a gain increasing from −7.3 to 3.6 dBi. The second is a double-layer vertically integrated third-order tunable filter/antenna that provides a constant absolute bandwidth over the tuning range. This design accounts for the frequency-dependent behavior of the antenna radiation $Q$ . The constant absolute bandwidth device is tunable from 1.65 to 1.90 GHz, has a maximum bandwidth variation of 45.3 ±7.4 MHz over the tuning range, and exhibits a gain from −6.1 to 4.3 dBi.

Properties of V-shaped metasurface fabricated on flexible substrate polyimide are numerically and experimentally explored at frequency of 4.3 THz. The results verify that anomalous refraction can be produced both for transverse electric and transverse magnetic polarized waves. However, different influences on excited antenna modes and polarization conversion are provided for different polarized incidences. Our results facilitate the application of metasurface in antenna radiation, polarization converter, THz communication, and so on.

In this paper, the radiation features of indoor WiFi energy-harvesting antennas are analyzed, and the design guidelines that enhance receiving power are proposed. It is acknowledged that an RF energy-harvesting antenna is desired to depict circular polarization (CP) and omnidirectional patterns, as ambient sources are omnipresent; however, the polarization and half-power beamwidth (HPBW) of the antenna are inconclusive in earlier studies. To clarify the requirement of the radiation characteristics for indoor environments, the receiving performance of six antennas with different HPBWs and polarizations is analyzed. The research methodology is a hybrid ray tracing algorithm that integrates image and shooting-and-bouncing-ray methods. These antennas are placed at different locations in a room, and the orientations are evenly and uniformly sampled. The receiving performance of each antenna is cast into cumulative density functions, which clarify the antenna that provides the maximum amount of successful receptions at specified energy-harvesting sensitivity. The simulated results are verified by performing the measurement. Surprisingly, the results indicate that CP and omnidirectional patterns cannot offer the most favorable receiving performance. In contrast, linear polarization and narrow HPBWs with high gain are desired in most of the scenarios, even though the directions of signal arrival have been uniformly sampled.

This paper presents a design methodology of three-dimensional (3-D) passive metallic waveguide-array lens antenna (MWALA) by implementing the Rotman lens concept (RLC) for collinear multi-beam radiations on the same angular plane. The RLC methodology extends the original concept of two-dimensional (2-D) tri-focal Rotman lens into a 3-D one in free space. Thus, the MWALA has a planar aperture facing to the radiation boresight to resemble a planar phased array of waveguide antennas and also has a curved focal surface profile (CFSP) on the opposite side to receive the illumination by the radiations of feed antennas. The three co-planar focal points are specified to define a circular focal arc (CFA) for multiple feed placement to radiate multi-beams through this MWALA. The boundary formed by the CFSP and CFA resembles the shape of Rotman lens equivalently realized in free space. In addition, the shortage of freedoms in conventional MWALA design limited to dual-focus configurations and resulting in narrow scan angles, is relaxed by adopting the phase velocities inside the waveguides as an additional freedom to realize a tri-focal configuration and broaden the scan angles of multi-beam radiation. Theoretical foundation and design guidelines are summarized with numerical and experimental examples presented to validate the feasibility.

Implantable antennas are mandatory to transfer data from implants to the external world wirelessly. Smart implants can be used to monitor and diagnose the medical conditions of the patient. The dispersion of the dielectric constant of the tissues and variability of organ structures of the human body absorb most of the antenna radiation. Consequently, implanting an antenna inside the human body is a very challenging task. The design of the antenna is required to fulfill several conditions, such as miniaturization of the antenna dimension, biocompatibility, the satisfaction of the Specific Absorption Rate (SAR), and efficient radiation characteristics. The asymmetric hostile human body environment makes implant antenna technology even more challenging. This paper aims to summarize the recent implantable antenna technologies for medical applications and highlight the major research challenges. Also, it highlights the required technology and the frequency band, and the factors that can affect the radio frequency propagation through human body tissue. It includes a demonstration of a parametric literature investigation of the implantable antennas developed. Furthermore, fabrication and implantation methods of the antenna inside the human body are summarized elaborately. This extensive summary of the medical implantable antenna technology will help in understanding the prospects and challenges of this technology.

Operation principle of non-coherent radar system (NCRS) is based on antenna radiation of electromagnetic waves into direction of an object of interest and receiving of reflected energy, its processing and information obtaining on parameters of this object, i.e., its coordinates—azimuth, elevation angle and range. NCRS structure is depicted.

The forward and the inverse problem of a thin, circular, loop antenna that radiates in free space is modeled and solved by using soft computing techniques such as artificial neural networks and adaptive neuro fuzzy inference systems. On the one hand, the loop radius and the observation angle serve as inputs to the forward model, whereas the radiation intensity is the output. On the other hand, the electric field intensity and the loop radius are the input and output, respectively, to the inverse model. Extensive numerical tests indicate that the results predicted by the proposed models are in excellent agreement with theoretical data obtained from the existing analytical solutions of the forward problem. Thus, the employment of artificial intelligence techniques for tackling electromagnetic problems turns out to be promising, especially regarding the inverse problems that lack solution with other methods.

The results of the research and development of the unified radiotechnical characteristic of aircraft radomes are presented: an increase in the level of antenna side radiation, associated with the presence of a radome in front of the antenna. It is shown that for an objective assessment of the radio engineering quality of radomes the integral characteristic is best suited – the average increase in the level of antenna radiation power in the required sectors of viewing angles. It has been demonstrated that this characteristic weakly depends on the properties of the antenna with which the radome is estimated.

In this paper, a multi-band antenna composed of irregular metal plate, input feeders and symmetrical defect ground is designed. The antenna radiation enhancement is improved by placing a rectangular artificial magnetic conductor array with zero phase reflection points corresponding to the multi-band antenna frequencies at a fixed distance below. The three impedance bandwidths of the antenna are 2.13-2.58GHz, 3.43-3.64GHz and 5.7-6.0GHz respectively, which effectively cover the 2.4/5.8GHz WLAN band and 2.5/3.5/3.8GHz WIMAX band. By adding AMC reflector, the performance of the antenna in the working frequency band is significantly improved, and a new frequency band is generated at 7.54-8.63 GHz.

An analytical method is proposed for determining the radiation resistance of a linear metal radiator. The method is based on using of the Poynting vector. The obtained results are compared with the results of solving the integral equation for a current in an antenna. The method is generalized to the case of radiators with nonzero boundary conditions. Calculation results are given.

In this paper, the scattered near-fields from electrically large complex PEC objects illuminated by far-field antenna sources are calculated by shooting and bouncing ray (SBR) method. In order obtain accurate near-field scattering results, an physical-optics (PO) near-field integral representation is proposed and reduced to closed form expressions to improve computing efficiency by applying locally expanded Green function approximations. By introducing the proposed PO near-field integral expressions, SBR can be used to analyze near-field scattering from a PEC target under far-field antenna sources radiation. The method is applicable to analyze the near-field scattering problem under arbitrary far-field source incident. Numerical example is presented to demonstrate the efficiency and accuracy of the proposed method.

This work presents a metamaterial structure to improve the isolation between two linear slotted waveguide arrays. The proposed decoupling structure consists of two columns of metal pin arrays that can suppress surface wave propagation. Also, the resulting structure only takes up a small space between the radiating slots of the two arrays. Simulated results show a 5 dB improvement in the inter-element isolation without a significant impact on the antenna radiation performance. Moreover, the reflection coefficient bandwidth can be slightly increased.

We propose an optimized approach for implementing Non-Uniform Fast Fourier Transform (NUFFT) algorithms under a general and new perspective for two-dimensional transformations. A case study of electromagnetic interest is carried out by applying the developed NUFFT to the radiation of a planar irregular array antenna onto a set of regular spectral points.

In this paper, a transmitting antenna fed by rectangular waveguide are intend for the operation at relatively high power levels in practical use, such as mid-range wireless charging. The proposed transmitter is composed of square patches on a 1.5mm thick dielectric substrate. The square patches are connected by main feeder and excited by rectangular feeding patches in the middle of the antenna. Single antenna is fed by a rectangular waveguide and sized for 370×480 mm (14.6×18.9 inch). The transmitting antenna is investigated by simulation and experimentally. The simulated results indicated that this antenna achieves 30dB gain and 150MHz bandwidth from 5.74 to 5.89 GHz. Experimental results are in accordance with those of the simulation results. The electromagnetic field distributions of antenna radiation direction have been characterized both in horizontal and vertical sections. Further analysis of the power density of the improved transmitting antenna is given.

International audience; Antenna characterization using reverberation chamber (RC) has become the new trend in RC measurements. In this work, we compare three antenna characterization methods in RC. These methods are applied in order to determine the radiation efficiency of a patch and a log-periodic antenna. Results are compared and show good coherence. The accuracy of the applied methods is discussed and a solution is proposed in order to enhance the accuracy of reference antenna based methods.

This paper describes an innovative system, named SSEEM, for co-polar and cross-polar radiation pattern measurements of earth station antennas. The SSEEM system is based on highly spread spectrum waveforms and, due to its high processing gain (PG), is able to overcome the limitations of the conventional approach used by satellites operators, based on transmitting a high-power continuous wave (CW). Indeed, the SSEEM system can operate in very low carrier-to-noise plus interference ratio regions (around -56dB for 72 MHz bandwidth). Consequently, it does not cause interference on adjacent satellites nor with a signal present within the satellite transponder used for the measurement. This means such tests can be carried out in any moment, without the need for a free satellite slot for transmission. In addition, the high PG allows for resolving even far side lobes of the antenna radiation patterns, without increasing transmission power, as in the CW case.

Forthcoming wireless systems are developed to support greater data rate and extra coverage area. This can be achieved with the help of multiple input multiple output and smart antenna techniques. One of the major rapidly emerging areas of communication is the smart antenna system which aids in attaining better coverage by increasing the signal strength only in the chosen direction. With effective optical beamforming techniques, the smart antenna systems demonstrate to be more competent in terms of excellence of signals in wireless communication. In this paper, a succinct outline of the smart antenna, an analysis and the comparison of different architectures of optical signal processing beamforming network (OSPBFN) is presented. The performance of OSPBFN is analyzed and the comparison is done for different architectures with the antenna radiation parameters. This paper can enhance the understanding of the ongoing research work in the area of OSPBFN.

In this Letter, a new polarising grid for a folded reflectarray is proposed to improve the aperture efficiency of the antenna. This polarising grid is designed using a partial grid and a director which can improve the antenna radiation characteristic. Consequently, the measured aperture efficiency of the proposed antenna with the new polarising grid is 60.49% at 77 GHz.

We propose a novel antenna design enabled by 3-D printing technology for future wireless intrachip interconnects aiming at applications of multicore architectures and system-on-chips. In our proposed design we use vertical quarter-wavelength monopoles at 160 GHz on a ground plane to avoid low antenna radiation efficiency caused by the silicon substrate. The monopoles are surrounded by a specially designed dielectric property distribution. This additional degree of freedom in design enabled by 3-D printing technology is used to tailor the electromagnetic wave propagation. As a result, the desired wireless link gain is enhanced and the undesired spatial crosstalk is reduced. Simulation results show that the proposed dielectric loading approach improves the desired link gain by 8–15 dB and reduces the crosstalk by 9–23 dB from 155 to 165 GHz. As a proof-of-concept, a 60 GHz prototype is designed, fabricated, and characterized. Our measurement results match the simulation results and demonstrate 10–18 dB improvement of the desired link gain and 10–30 dB reduction in the crosstalk from 55 to 61 GHz. The demonstrated transmission loss of the desired link at a distance of 17 mm is only 15 dB, which is over 10 dB better than the previously reported work.