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In this paper, a meta-surface inspired flexible antenna prototype is proposed for bio-medical applications. A 1.5 mm Rogers high frequency laminate with permittivity of 3.3 and loss tangent of 0.002 is used as substrate owing to its flexible nature. The proposed antenna is suitable for on-body applications and as such the performance of the prototype was verified on a multilayer phantom model using HFSS tool. Unique properties of meta-surface make miniaturization of the antenna possible with optimum antenna dimensions of 0.24 λ 0 × 0.15 λ 0 × 0.013 λ 0 . The designed antenna is investigated for on-body applications and thereof it is observed that the radiator radiates in the range of 2.14 GHz − 3.4 GHz resulting in resonance at 2.67 GHz.

Modified split-ring resonators (SRR) are used develop a high gain UWB antenna for microwave imaging applications. This paper analyzes two different ground designs for the proposed patch radiator with modified SRR; defected ground structure and the second one is rectangular slotted ground. Two SRRs are placed on the circular radiator patch element, each in the shape of alphabet letters ‘S’ and ‘V’. The results of the first design with DGS demonstrate that the reflection coefficient is well below −10 dB in the frequency range from 1.9 GHZ −11.9 GHz with the fractional bandwidth of 110%. Further modification in the resonant modes of UWB is obtained by introducing single rectangular slot on the ground plane. This helps in eliminating the lower band from 1.9 GHz to 6 GHz. This band rejection helps in alleviating the interferences caused by other unlicensed wireless applications lying in sub 6GHZ band.

Recent studies showed that nanofluids are considered as a promising way to enhance the heat transfer properties of coolants. Currently, in a car radiator forced convection heat transfer method is carried out to cool circulating fluid. The mixture of water with either ethylene or propylene-glycol is necessary to lower its freezing point and eliminate ice formation. However, the boiling point of deionized water can be pushed up by mixing it with anti-freezing materials like ethylene glycol (EG). Hence the present research work focuses on the heat transfer characteristics of nano-fluids with different combinations of EG and deionized water (60:40, 30:70, and 20:80) along with graphene oxide (GO) nanoparticles (0.1 % wt). The heat transfer potential of graphene oxide/ deionized water-ethylene glycol nanofluids is experimentally investigated in coolant application for car radiators, in which the coolant flow rate is varied from 180 to 420 (LPH) at a fixed coolant temperature of 90 °C. The evaluation of stability is performed using visual inspection and zeta potential test. The density of nanofluid was determined by oscillating U-Tube density meter. The optimized combination of 60% EG, 40% DW and 0.1 wt% GO exhibited higher heat transfer characteristics of the radiator system used. The maximum heat transfer enhancement of 42.77% at 300 LPH, 18.14% at 360 LPH, and 71.1% at 240 LPH for 60:40 EG/DW-based GO nanofluids were obtained. The maximum Nusselt number value of 192 at 420 LPH was observed for 60:40 EG/DW-based GO nanofluid as compared with 20:80, 30:70 EG/DW-based GO nanofluid. It is estimated that by replacing conventional coolant with this nanofluid, reduction in the frontal area of radiator is done which gives more flexibility for industrial design, more eco-friendly vehicle which produces less drag and hence less the fuel cost.

A low-profile single-layer end-fire circularly-polarized (CP) antipodal linearly tapered slot antenna (ALTSA) is proposed and investigated through simulations and experiments. This antenna is a composite structure consisting of a novel width-tapered slotted substrate integrated waveguide (SIW) and an ALTSA fed by the SIW. The former also serves as a radiator to produce vertically polarized radiation, which is crucial to achieve a fully planar end-fire CP antenna when a thin substrate is deployed. Compared to the previous ALTSA fed by the SIW, this proposed antenna utilizes slots on the spare broad walls of the SIW to form an extra slotted width-tapered SIW radiator, which presents an extension of the conventional width-uniform slotted SIW. Moreover, there are no space harmonics in the slotted width-tapered SIW; it is a slow wave that produces the vertically polarized radiation. The proposed antenna is demonstrated at 28 GHz, which is one of the millimeter-wave bands specified for 5G. An experimental prototype of the antenna has an impedance bandwidth of about 9 GHz from 23.8 GHz to 32.8 GHz and an axial ratio bandwidth of about 1.4 GHz from 27.35 GHz to 28.75 GHz, which coincide well with simulated results.

This paper presents a dual-polarized Frequency-scaled Ultra-wide Spectrum Element (FUSE) array on a triangular lattice, precision-machined from an Aluminum block as a self-supporting structure, similar to all-metal Vivaldi arrays reported by the authors in past work. Whereas dual-polarized FUSE arrays normally consist of offset radiator pairs conforming to the ubiquitous square-lattice egg-crate configuration and capacitively coupled at the ends to achieve ultra-wideband operational frequency ranges, this work is novel in that it uses conventional manufacturing to directly machine the dual-polarized FUSE array on a triangular lattice instead. Triangular lattices for dual-polarized wideband arrays are uncommon in the literature and have the benefit of 15.5% reduction in element counts over a square lattice aperture of the same footprint and upper frequency of operation, making this a useful development for applications requiring minimum element counts, i.e., reduced cost/weight. In this paper, embedded element performance predictions for the dual-polarized triangular-lattice FUSE array are presented and validated with measurements of a hardware prototype. Results show similar overall grating-lobe-free performance to a square lattice FUSE array of the same footprint and operational frequencies reported in earlier work. The asymmetries of the triangular lattice result in relative performance degradation vs. square lattice FUSE arrays as a trade-off to the benefit of reduced element counts for apertures of similar size.

A dual wideband antenna with a large beam steering angle through endfire radiation and frequency scanning radiation in each band is proposed for the first time. The antenna utilizes a double-layer spoof surface plasmon polaritons (SSPPs) structure, which exhibits stronger field confinement and lower cut-off frequency than the single-layer SSPPs structure. The modulated double-layer SSPPs structure can excite the space harmonic distributing in the fast-wave region and retains transmission in the slow-wave region. By combing the modulated double-layer SSPPs waveguide and the Vivaldi radiator, both the slow-wave radiation (endfire mode) and the fast-wave radiation (frequency scanning mode) can be aroused in the two operating bands. An example antenna is designed and fabricated. In the slow-wave range from 3 GHz to 9 GHz, the antenna works in the endfire mode with the beam direction of 90° and the realized gain varying from 3.55-8.24 dBi. Within the fast-wave band from 13 GHz to 34 GHz, the antenna operates in the frequency scanning mode, accomplishing beam scanning from -90° to ±42.5° with the realized gain of 9.45-15.67 dBi. Thus, the proposed dual-band antenna can achieve two operating bands and two radiation modes, which offers a 1800 beam changing angle in total.

A compact body-worn circular polarized textile monopole antenna for wearable applications is reported. The proposed antenna is fabricated on a jean fabric providing flexibility, light-weight, and easy integration into human clothes. The overall size of the proposed antenna is 25 × 30 × 1.4 mm3. Circular polarization (CP) is advantageous for on-body communication as it provides features such as multipath immunity, suppressing interferences, and enables better link connectivity between the sensor nodes. The proposed antenna achieves the CP using an asymmetric stepped L-shaped ground plane and through the incorporation of cross-shaped stub in the radiator. The single fed octagonal strip monopole antenna provides good impedance matching over the entire ultra-wide frequency range from 3.09 -11 GHz. Simulation results are in good correlation with the measured results. Axial ratio bandwidth < 3 dB is achieved in the frequency range of 3.4-10 GHz. Gain and efficiency obtained are about 2.3-4.4 dBi and 65-82% at the said frequency range respectively. Structural deformation is performed to analyze the flexibility of the proposed antenna. The simulated SAR values follow the FCC limit making it most suitable for wearable applications.

The objective of the paper is to evaluate the Engine cooling performance of the light commercial vehicle by data acquisition. The data acquisition is done following Indian standard, IS: 14557:1998. Sometimes, the ambient temperature conditions and actual vehicle parameters may differ, then as mentioned in standard, thus making it necessary to go beyond standard conditions. The methodology of testing is to acquire data and compare the thermal behaviour in five different vehicle configurations. In the first case, a subjected vehicle was operated with a conventional fixed fan that is permanently engaged and a smaller radiator, which more or less resulted in overheating of the vehicle. Then in the second case, data is acquired with a viscous fan, bigger core radiator, fresh air cleaner. The viscous fan operates only when the coolant temperature goes beyond a specified limit. It gives a better cooling performance, lower cabin noise, and higher fuel efficiencies. In the third case, a fresh air cleaner is replaced with a clogged air cleaner, to simulate extreme dusty, off-road conditions like mining, where power and torque demand is maximum and the vehicle operates at lower vehicle speeds. In the fourth and fifth cases, experiments were conducted to check the actual performance of the vehicle on plain roads and hilly routes for a better driving simulation. The specific finding of the paper is that a vehicle may clear the cooling performance according to the standard requirements, but it may fail in the actual field conditions. So, a factor of safety must be considered while designing an engine cooling system, which makes it fit for worse field applications. Finally, the gathered data is used to upgrade the engine cooling management system.

A compact dual-band circularly polarized microstrip ring antenna for GPS L1 and L2 bands is proposed. The antenna comprises a two-ring radiator and a multi-ring-etched ground, forming two Yagi-Uda double-ring antennas, respectively. It operates in dual bands with a small ground size and unidirectional radiation. The proposed antenna yields right-hand circular polarization and fully covers GPS L1 and L2 bands.

In this article we present a miniaturized multiband metamaterial-based antenna for array applications, operating with good radiation performance over the LTE and UMTS uplinks within the 800–3000 MHz range. Each antenna element consists of a radiator and a metamaterial reflector. The former is a miniaturized Archimedean spiral antenna with an integrated matching line. The latter is placed 39 mm below the radiator and is shared among the multiple elements in the array application. The radiator is very compact, a square of 75 mm per side, equivalent to only 0.2 (0.75) times the free-space wavelength at 800 MHz (3000 MHz). The reflector is incorporated to achieve half-space radiation and is implemented with a novel multi-layered metamaterial structure to improve the radiation efficiency. The metamaterial, moreover, is used in a non-conventional way. In fact, we take advantage of its complete phase-response function, behaving, thus, as magnetic or electric conductor in different parts of the band. In this way, the in-phase reflection is not limited by the typical narrow bandwidth of artificial magnetic conductors. The measured S11 parameter is less than -8 dB and the simulated gain is greater than 4.2 dBi in a range exceeding the one covered by the UMTS and LTE uplinks. Furthermore, a 2×2 antenna array was also built. The reflections of each element are similar to those obtained in the single-element antenna.

This paper presents an effective design method to integrate bandpass filtering response into an aperture-fed dual-polarized magneto-electric dipole antenna (ME-dipole). The antenna is composed of a traditional ME-dipole radiator and a modified aperture-coupled feeding structure. In one aspect, highpass filtering radiation response is realized by approximating the antenna radiator as a highpass filter network. In another aspect, by developing an improved aperture-coupled feeding structure with lowpass filter characteristic, the antenna obtains lowpass filtering radiation response. As a result, bandpass filtering radiation response is achieved. Since no intricate filter resonators are used, the in-band antenna gains are not degraded. The highpass/ lowpass filter networks are studied and specific radiation nulls generated by the two networks are analyzed. For demonstration, a single-polarized model is presented first and its working mechanism is studied in detail. It realizes a 78.6% impedance bandwidth, flat in-band gains of 7.5 -7.8 dBi, and more than 22 dB out-of-band radiation suppression level. Then, based on the same methodology, a dual-polarized antenna model is developed with 69.3 % operating bandwidth, 7.1 -9.3 dBi measured in-band gains and integrated bandpass filtering radiation response.

In this communication, we propose a shared-radiator design concept for dual-band base station antenna arrays. To realize the concept, novel differentially fed dual-polarized slot antenna is devised to be the high-band (HB, 3.4-3.6 GHz) radiator, while the large slot ground can be reused as the radiating arm of the low-band (LB, 0.69-0.96 GHz) crossed dipole. Reflective cavities are introduced to back the HB antennas, building clear and independent radiating environments for the two operating bands. A dual-band base station antenna array with one LB dipole antenna and four HB slot antennas is designed, by adopting the proposed integration concept. Good impedance matching (voltage standing wave ratio 29.5 dB in the LB and > 26.6 dB in the HB) are obtained. Owing to effective decoupling between the two bands, stable radiation patterns are also achieved.

Wideband slot-coupled microstrip antenna (SCMSA) is a distinctive electromagnetic wave radiator in recent years with wide bandwidth and low profile. In such a wide frequency range, the electric distance, i.e., normalized to operating wavelength, between dual equivalent magnetic currents increases obviously with upward frequency. Therefore, the realized gain is usually with a large variation, which limits the wideband performance of SCMSA. In this paper, a feasible method is proposed to stabilize the realized gain of a SCMSA over its entire impedance bandwidth by utilizing a properly designed reflector-plus-sidewall structure (RPSS), which includes a reflector with an optimized height and two vertical sidewalls. Each part has its own function in realized gain compensation and enhancement, performing a flatter and higher realized gain in a wide frequency range. To validate this method, an antenna prototype is fabricated and tested. Compared with the referenced SCMSA, the measured results indicate that the proposed one adding RPSS maintains a wide impedance bandwidth of 24.8% (3.75-4.81 GHz), but reduces gain variation from 4.1 dB to 0.5 dB (10.5-11 dBi) with an average realized gain increment of 2.1 dB.

In this work, an ultrawideband spoof surface plasmon polariton (SPP) bidirectional endfire antenna is proposed based on wave vectors’ mismatching. One splitter structure connects two radiator structures to form the proposed antenna, and two types of slot lines are used to design the splitter structure and the two radiator structures. Although the spoof SPP can transmit to the two radiator structures from the splitter structure, the wave vectors of the spoof SPP in the splitter structure and radiator structures are mismatched. Thus, the spoof SPP from the splitter structure will not be bounded mode when it propagates at the two radiator structures and will be decoupled by the two radiator structures, thereby realizing a bidirectional endfire radiation pattern. The bandwidth of the proposed antenna depends on the decoupling bandwidth of the spoof SPP based on wave vectors’ mismatching, which is determined by the working band of the splitter structure and the dispersion of radiator structures. This proposed antenna has a relative bandwidth of 120% from 9.6 to 40.00 GHz, average efficiency of 93%, and an average gain of over 9.2 dB, having great potential in microwave and millimeter communications.

To improve the operating efficiency of proton exchange membrane fuel cells (PEMFCs), an optimal coordinated control strategy for addressing the poor coordination problem between the water pump and radiator in a PEMFC stack heat management system is proposed in this paper. To this end, a cooperative exploration strategy large-scale multiagent twin-delay deep policy gradient (CESL-MATD3) algorithm has been developed for this control strategy. In this algorithm, both the water pump and radiator are treated as individual agents, and the strategies of centralized training and decentralized execution are applied; thus, coordinated control over the two agents is realized. Moreover, the concepts of curriculum learning, imitation learning, and various novel parallel computing techniques are incorporated into the design of this algorithm, resulting in enhanced training efficiency; thus, a coordinated control strategy with better robustness is obtained. According to the experimental results, compared with other advanced control algorithms, this coordinated control strategy-based algorithm achieves better performance and robustness for PEMFC stack temperature management. The proposed method can effectively improve the response speed of the controllers, reduce the fluctuation and oscillation of the stack temperature and the temperature difference between the stack outlet and inlet (stack temperature difference) during heat management, and reduce the maximum overshoot of the stack temperature by 99.12% and of the stack temperature difference by 97.97%.

Introduction. Introduction. Low-profile effective antenna systems (AS) with maintained directional characteristics in a wide sector of scanning angles are required for satellite communication at mobile objects. This article investigates the directional characteristics of a subarray based on a Fabry–Perot cavity and an antenna array with mechanoelectrical beam steering.Aim. To investigate a Fabry–Perot based antenna array with mechanoelectrical beam steering and to estimate its gain and directivity at different scanning angles.Materials and methods. Computer simulations were carried out using the finite element method (FEM), finite difference time domain (FDTD) method and template based post-processing.Results. A subarray based on a Fabry–Perot cavity for an antenna array with mechanoelectrical beam steering was simulated. The efficiency of the subarray comprised at least 65 % in the 11.9…12.5 GHz frequency band. An antenna array based on a Fabry–Perot cavity with mechanoelectrical beam steering was developed and investigated. The calculated characteristics of the developed antenna array agreed well with those obtained experimentally. The gain degradation did not exceed 2.5 dB in the 0…70° scanning angle range. The advantages of using antenna elements based on a Fabry–Perot cavity and developing on their basis mobile satellite antenna systems with wide-angle scanning are noted.Conclusion. The use of a radiator based on a Fabry–Perot cavity and the development on it basis an antenna array with mechanoelectrical beam steering provides an antenna efficiency of no less than 0.5 with a gain degradation of no more than 2.5 dB in the scanning angle range 0…70° from 11.9 to 12.5 GHz.

In this paper, a two-port dual-band antenna is designed with high isolation. The beak-shaped radiator and open stubs are used to achieve miniaturization of the antenna. A T-shaped stub is used to i...

We propose a wideband, low-cost, and portable antenna that includes three sections of straight wire radiator, high-impedance Transmission Line (TL), and a matching network inside the base antenna, ...

To simultaneously cover multiple wireless services and protocols, the antenna in communication devices should operate over a wide and ultra-wide frequency band. The use of wide/ultra-wideband antennas not only lessens the number of antennas necessary to cover multiple frequency bands but also decreases the system complexity, size, and costs. To operate over the ultra-wide frequency band, in this paper a CPW-fed small antenna is reported for portable communication devices. The anticipated antenna comprises a bow-tie-shaped patch and two ground planes. One inverted L-shaped and one extended U-shaped ground plane are asymmetrically placed with the main radiator which helps the antenna prototype to realize a functional band of 3.05 – 11.25 GHz (VSWR ≤ 2). In the functional band, the studied antenna accomplished a maximum peak gain of 4.98 dBi and maximum efficiency of 94.4%. Moreover, it exhibits symmetric omnidirectional radiation patterns and good time-domain behavior. The lucrative characteristics such as simple design, very small size (24.5 × 20 mm2), ultra-wide operating band, good gain and efficiency, stable radiation characteristics, and good time-domain characteristics make it a potential candidate to be used in portable communication devices.

In this article, compact a multiple-input and multiple-output (MIMO) system with flag-shaped radiators and a mountain-shaped ground plane is presented. Isolation is enhanced with the help of a decoupling stub placed between radiators, where two bands are stopped with the help of slits etched into the radiators. The overall size of the proposed antenna is 15 mm ×25 mm ×1.6 mm. The reflection coefficients are less than -10 dB between 3–10.9 GHz, except the bands WiMAX (3.2–3.7 GHz) and WLAN (5–6 GHz); similarly, measured and simulated transmission coefficients are less than -20 dB across the entire band of UWB. The envelope correlation coefficient (ECC) is less than 0.02 and the diversity gain is greater than 9.9 dB. The gain, ECC, radiation pattern, multiplexing efficiency, diversity gain and various other parameters are discussed and evaluated in detail.

Contactless transportation systems based on near-field acoustic levitation have the benefit of compact design and easy control which are able to meet the cleanliness and precision demands required in precision manufacturing. However, the problems involved in contactless positioning and transporting cylindrical objects have not yet been addressed. This paper introduces a contactless transportation system for cylindrical objects based on grooved radiators. A groove on the concave surface of the radiator produces an asymmetrical pressure distribution which results in a thrusting force to drive the levitator horizontal movement. The pressure distribution between the levitator and the radiator is acquired by solving the Reynolds equation. The levitation and the thrusting forces are obtained by integrating the pressure and the pressure gradient over the concave surface, respectively. The predicted results of the levitation force agree well with experimental observations from the literature. Parameter studies show that the thrusting force increases and converges to a stable value as the groove depth increases. An optimal value for the groove arc length is found to maximize the thrusting force, and the thrusting force increases as the groove width, the radiator vibration amplitude, and the levitator weight increase.

To maintain the compactness of future 5G smartphones, integration of sub-6 GHz and millimeter-wave (mm-wave) bands is a challenging task due to the large frequency ratio. We, therefore, propose a single-fed triple-band antenna with a large frequency ratio. The proposed antenna is composed of a microstrip patch radiator with an inverted U-shaped slot for dual-band operation in the mm-wave frequencies (28 and 38 GHz). A meandered radiating structure is linked to the microstrip patch radiator through a compact microstrip resonant cell (CMRC) low-pass filter (LPF), which is used for the integration of these structures to be operated at 3.5 GHz. A compact size of 22 mm $\times10$ mm $\times0.508$ mm for the proposed antenna was realized by incorporating the radiator slot, an LPF, the truncated ground, and a meandered line structure. Wide, decoupled −10 dB bandwidths of 12.9%, 5.8%, and 2.4% at 3.5, 28, and 38 GHz, respectively, were realized for the proposed MIMO antenna without utilizing an external decoupling structure. A detailed safety study with respect to specific absorption rates and power densities was analyzed in data, reading, and talking modes. Finally, the measurements were performed in an anechoic chamber, and the measured results were in a good correlation with the simulation results.

This article proposes a single band circularly polarized (CP) rectenna operate at a 2.45 GHz Wi-Fi band, using a hexagonal shape of a microstrip radiator and a voltage doubler rectifier for smart c...

This paper proposed a novel compact design of UWB antenna. Our design used an uni-planar EBG double-layer of FSSs to enhance performance characteristics of UWB antenna in operation frequency of 14 GHz/Ku Band. This UWB antenna occupies a compact size of 40.36 × 29.36 mm2 with space/gap between the radiator patch and double-layer of FSSs is 10 mm. We used a simple rectangular truncated-corner as a radiating patch. Double-layer of FSSs consist of a lower layer of FSS that used a unit cell of rectangular loop and an upper layer of FSS applied a wire grid. Optimized size of the truncated-corner is 2 × 0.5 mm2, optimal space/gap between radiator patch and double-layer of FSSs is 10 mm, and the width of a rectangular loop in the lower layer of FSS is 1.742 mm. Our proposed uni-planar EBG double-layer of FSSs based UWB antenna reaches S11 parameter of −42.381, a −10 dB impedance bandwidth of 1.941 GHz (12.964–14.905 GHz), and a VSWR of 1.0154 in operation frequency 14 GHz. In addition, our UWB antenna design has a high gain about 6.1 dB. Applying of uni-planar EBG double-layer of FSSs improve significantly the performance characteristic of UWB antenna.

This chapter deals with two topics that have much overlap, the multi‐beam antenna (MBA) and the phased array (PA). MBAs were developed in the 1990s and 2000s to provide a large number of higher‐gain, smaller beams, in order to raise the capacity in the overall coverage area. MBAs are mostly used to create a large number of spot beams. The chapter considers PAs in their less common application of forming one or a few contoured beams with a reflector. It considers all aspects of these topics including the various antenna schemes, the reflectors, the radiating elements, the beam‐forming network (BFN) for a PA, PA amplification, and MBA testing. A PA is an array of radiating elements all of the same kind, laid out in a regular grid, that forms beams by means of BFN. A patch or ring‐slot radiator is one of the most useful radiating elements for PAs because of its wide scan capability.

In this communication, a compact, highly integrated multiplexing filtering antenna operating at 4.7/5.2/6.0/6.6 GHz is proposed for the first time. Different from traditional antennas, the proposed antenna has one shared radiator but four ports working in different frequency bands, and thus, it can simultaneously support four different transmission channels. The proposed multiplexing antenna is composed of a patch with a U-shaped slot, two substrate integrated waveguide (SIW) cavities, and four resonator-based frequency-selective paths. The resonator-based paths can not only enhance the interchannel isolations but also improve the impedance bandwidth. The design principles and the methods of controlling the four operating bands are studied. Measurement results agree reasonably well with the simulations, showing four channels from 4.5 to 4.8 GHz, 5.1 to 5.3 GHz, 5.85 to 6.3 GHz, and 6.4 to 6.6 GHz, respectively. The antenna also exhibits high isolation of over 25 dB between the channels. In addition, the proposed antenna has a consistent broadside radiation pattern and polarization in the four bands, and manifesting the proposed multiplexing filtering antenna can be a promising candidate for multiservice wireless communication systems.

In this letter, a multibeam antenna based on metasurface (MS) is proposed. By employing the partially reflecting defected MS as the radiator, taking port 1 as an example, the beam with multiple sidelobes is focused in the direction of (3°, 33°) and the peak gain increases from 6.3 to 10.57 dBi. Also, a narrow beam with half-power beamwidth of 31° is obtained in a dimension of 1.5 λ 0 × 1.5 λ 0. When the antenna is fed from different ports separately, the beams are steered in different directions. Also, through inserting the vias between two-layer patches of the MS unit, the sidelobe is suppressed and the gain is improved. The results indicate that the antenna can operate at 7.5 GHz. When four ports are separately excited, the antenna can radiate four beams pointing at ( ϕ , θ ) = (3°, 33°), (93°, 33°), (183°, 33°), and (273°, 33°).

The supply of heat to oil media pumped by pipeline transport systems is one of the main problems in the oil industry. The article describes a method for supplying heat to oil-containing media using the energy of an electromagnetic field. The possibility of releasing surfaces in contact with oil sludge under the influence of electromagnetic fields has been shown by experiment. We describe the design and parameters of a biconical horn radiator of a microwave electromagnetic field operating at a frequency of 2 450 MHz. A method for generating energy and transmitting it to the emitter by means of a coaxial cable is shown. Testing the emitter in oil placed in an optically transparent and radio-tight double-walled tank is presented. The design of the stand allows us to safely examine the thermal process using a thermal imager. The installation made it possible to heat 7 liters of oil at 15 °C in 12 minutes.

A dual-polarization microstrip multiple-input-multiple-output (MIMO) antenna for 5G mobile phone applications is proposed in this communication. Eight differentially fed microstrip antenna elements are arranged on the back cover of a mobile phone. Four shorted radiation patches constitute the radiator of an antenna pair, and four antenna pairs form an eight-element MIMO antenna. The antenna element can excite two modes by utilizing the interaction of the two elements of one antenna pair and has a wide operating band. A prototype of the MIMO antenna is fabricated, and eight power dividers are applied to provide the differential feeding. The measured −6 dB impedance operating band is 4.37–5.5 GHz and can cover the N79 band (4.4–5 GHz) for 5G. The measured efficiencies of the antenna elements with a low profile of 1.2 mm are 40%–50% in the N79 band though the substrate has a high loss tangent of 0.02. The measured results show that the MIMO antenna has low mutual couplings of lower than −22 dB, low envelope correlation coefficients (ECCs) of lower than 0.068, and the ratios of mean effective gains (MEGs) of lower than 2.28 dB. Some issues in practical applications are discussed. The proposed antenna provides a promising solution to design a compact and pony-size MIMO antenna without occupying the inner space or ground clearance of a mobile phone.

Nanofluids have emerged as potential prospect coolant in heat transfer applications. Hybrid nanofluid is the is the recently developed class of nanofluids having two different types of nanoparticles suspended in the base fluid. In this research, a novel hybrid nanofluid containing Fe2O3-TiO2 (50:50) nanoparticles suspended in water basefluid has been used to improve the convective heat transfer in aluminum tube automotive radiator. Three hybrid nanoparticle concentrations (0.005 vol.%, 0.007 vol.% and 0.009 vol.%) were tested. Effect of inlet temperature and fluid velocity on heat transfer rate was examined by varying the inlet temperature from 48 °C to 56 °C and flowrate from 11 LPM to 15 LPM. Heat transfer rate increased by a maximum of 26.7% at 56 °C inlet temperature, 15 LPM flowrate and 0.009 vol.% nanoparticle concentration. At aforementioned operating conditions, Nusselt number increased by 20.03%. Increase in inlet temperature from 48 °C to 56 °C increased the heat transfer rate by 8%. Past 0.009 vol.% concentration, nanoparticle clogging diminished the stability of hybrid nanofluid which results in overall performance deterioration.

In this communication, leaky-wave antennas (LWAs) at mm-wave bands are designed on the metal rims of the mobile handsets for mm-wave communications. Two different LWAs, constructed from the rectangular slits and the stepped slits, respectively, are designed at the same frequency band, with their main lobes pointing to different directions. Since the LWAs are narrow, two layers of LWAs can be accommodated along the height of the frame. Hence, the metal frames around the mobile chassis are built by twelve LWAs in total, with four LWAs along each longer edge and two LWAs along each shorter edge of the chassis. Unlike traditional mm-wave antennas in the mobile handset, phased array or feeding networks are not required for the proposed antenna system. The antenna covers a bandwidth from 26.8 to 28.3 GHz. Its coverage efficiency reaches 50% for the gain of above 5.4 dBi, which is better or at least comparable with the phased arrays in the handsets. Due to the distributed arrangement, the antenna system is robust to hand effects and real-life components integrated in the handset. In addition, the LWAs are codesigned with the sub-6 GHz antenna, which reutilizes the shorter frames as the radiator. The whole antenna system has been fabricated, with the measured results agreeing well with the simulated ones.

We present the results of modeling the temperature distribution in a “Package-on-Package” type microcircuit. The microcircuit will be used as a distributed system controller to collect and to multiparametrically analyze the information. The microcircuit case consists of two vertically connected substrates with the memory and the processor dies. On the basis of an analysis of the microcircuit design, we show the thermal peculiarities of its operation mode governed by the “processor–main heat source–location and installation” method. To determine the die temperatures during the stationary operation mode, we created a three-dimensional numerical model consisting of the microcircuit case, the system printed circuit board, and the upper radiator. We propose model simplifications by means of using the efficient values ​​of the thermal conductivity coefficients. The key parameters of the model most strongly affecting the temperature of the dies are the levels of copper filling in the system printed circuit board and in the lower microcircuit substrate, as well as the number of the transient holes in the processor mounting area. We investigate the die temperature dependences on these parameters in the stationary mode under a total heat release of 7.8 W and reveal the optimal parameter values ​​making it possible to significantly reduce the die temperature. The results obtained may be useful in development of multichip microcircuits with vertical chip integration.

This study aims at evaluating and comparing the thermal performance of five different engine coolants employed in an experimental engine cooling system with a flat-tube louvered-fin automobile radiator. For this purpose, a PLC-controlled test system was set up. The system could maintain the temperatures of the air and coolant at the radiator inlet, the speed of the air and flow rate of the coolant at the required values during the tests. The tested coolants were pure wa-ter, 30/70 ethylene glycol (EG)/water, 30/70 propylene glycol (PG)/water, 50/50 EG/water and 50/50 PG/water mixtures. In all tests, the coolant temperature at the radiator inlet was kept at 90°C, while the coolant flow rate was varied between 0.10–0.25 l/s with 0.05 l/s increments. Furthermore, the air temperature at the ra-diator inlet was kept at 25, 30 and 35°C, and the air speed passing over the radia-tor was varied between 1–4 m/s with 1 m/s increments. The thermal performance of the radiator was evaluated by locating the measured coolant flow rate and coolant inlet/outlet temperatures into the conservation of energy equation. It was found that water yielded the highest radiator heat rejection rates. Compared with water, 30/70 EG/water, 50/50 EG/water, 30/70 PG/water, 50/50 PG/water mix-tures yielded on average 3.50%, 7.89%, 8.28%, 11.46% lower radiator heat rejec-tion rates, respectively. Since PG has some advantages over EG such as lower cost and toxicity, PG mixtures can be employed as antifreeze instead of EG mix-tures in expense of a slight decrease in the thermal performance.

A faster time performance can be achieved by focusing on prompt emitted photons, such as Cherenkov photons. In this study, the time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators were first simulated, and we evaluated the detector performance and discussed ways to improve the coincidence time resolution (CTR) results for the detector with the three radiators. Finally, we compared detection efficiency of Cherenkov radiation in three radiators. In this work, we recorded the step-by-step information of Cherenkov photons and the electrons that produced them in the radiator, information of photons on the photon outputting surface, and the step-by-step information tracing of the parent charged particles (electrons) to evaluate the factors influencing the performance time of the detector based on Geant4. Specially, we usually use a photon amplitude timing in the experimental implements, and the arrival time of an event is defined as the arrival time of the first photon of the event accordingly. The time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators with a 5 mm length were simulated as 28.5 ps for PbF, 40.1 ps for PbWO4, and 24.7 ps for Al2O3. After considering other factors such as quantum efficiency (QE) of 30% and transit time spread (TTS) of 10 ps from the process of practical electronics, the CTR of a pair of single-pixel detectors were 56.6 ps for PbF2, 78.8 ps for PbWO4, and 46.3 ps for Al2O3 with a thickness of 5 mm. The detection efficiency of PbF2 is 32.25%, PbWO4 of 31.91% and Al2O3 of 8.14% in the case of 5 mm length. The simulation results indicated that using the Cherenkov photons produced in PbF2, PbWO4, Al2O3 for detector timing can obtain good CTR results. In this study, it demonstrates that it is possible to achieve a pretty good CTR with an improved QE and a reduced TTS of the photodetector.

The CBU type motorcycle (completely built up) had components imported from abroad. The advantages of handling a light motorbike, a large motor power and a DOHC engine. One of the weaknesses of which is the engine that heats up quickly even though it uses a radiator as the cooling system. In the performance test of the CBU Yamaha R6 and Honda CBR600F4I motorbike engines, the fuel was used for the Pertamax turbo type with an octane value of 98 to make the engine stable at high compression. The resulting performance of the gasoline motor is in the form of torque and power data using a dynamometer. How to see the performance data of a gasoline motor can make measurements on the crankshaft, input the temperature and output of the combustion system chamber as well as the ambient temperature. The research aims to see the performance data of the two machines. The method will produce experimental data analysis in graphs and tables. The biggest performance was obtained from the CBU type Honda CBR600F4I motorbike engine with Pertamax turbo fuel, namely with a torque of 46.74 Nm, at 13,630 rpm and a power of 114.48 Hp, while the Yamaha R6 motorbike engine with Pertamax turbo fuel only had a torque of 40.65 Nm, at 12,600 rpm and a power of 90.81 Hp

This letter presents a compact triple-band antenna composed of a spiral radiator with an open-ended slot at the ground for human head-implantable wireless communications. It operates simultaneously at a Medical Implant Communications Service (MICS) band (402–405 MHz), a Wireless Medical Telemetry Service (WMTS) band (1427–1432 MHz), and an Industrial, Scientific, and Medical (ISM) band (2400–2480 MHz). The proposed antenna has a thin profile of 0.5 mm with a volume of 197 mm3. Semisolid phantoms are used for the design and experimental validation, and detailed parameter studies are carried out to determine the working principles of the antenna. Based on simulations and measurements, it was found that the proposed antenna covers all the desired frequency bands with comparably high boresight gains given its compact dimensions.

A simple compact circularly polarized (CP) cross slot antenna with a wide frequency tuning range has been presented in this letter. Four identical varactors are loaded at the ends of the cross slot for varying the operating frequency, and only one voltage is adopted to control the varactors. Distributed inductors and capacitors are employed to realize CP radiation. By varying the value of varactors, a wide tuning frequency range of 41% (1.65–2.5 GHz) is achieved. Stable CP radiation patterns are obtained for all frequencies across the entire operating bandwidth. The proposed antenna is a good radiator that can be used for Internet of Things (IoT) wireless sensing network, WiFi applications, and reconfigurable array developments.

The present study focuses on the energy performance, entropy generation, and irreversibility of the use of nanofluid in an industrial Peugeot automobile radiator (size: 250 x 301 x 60.4 mm, channel number: 34 and hydraulic diameter: 1.923 mm) with a louvered fin type. 50:50 EG - water which is widely used in existing automobile radiators and a new generation of EG - water - Al2O3 (0.5%) nanofluid have been compared. In order to examine the effect of variable operating conditions on thermal performance for both fluid mixtures, experiments have been performed at variable air velocity (4-5 m/s), variable coolant flow rate (10-15 - 20 It/min), and an inlet temperature of 95 degrees C (real automobile conditions). Thermohydraulics calculations such as entropy generation, irreversibility, effectiveness, NTU, heat transfer rate, pumping power have been obtained from experimental data. Among conducted experiments, with increasing coolant flow rate, entropy generation increases on the airside, while decreasing on the coolant side. When the entropy generation due to temperature and pressure difference is compared, entropy production due to pressure difference can be neglected. It has been evaluated that the use of nanofluid increases the heat transfer rate by 9.52%, reducing the irreversibility by about 68% at the 4 m/s air velocity and 10 It/min coolant flow. (C) 2020 Karabuk University. Publishing services by Elsevier B.V.

This article describes a method for electrodynamic modeling of strip radiating structures based on a chiral metamaterials using of an apparatus of hypersingular integral equations. A mathematical model of such radiating structure with an arbitrary emitter width is presented. The method provides high calculating accuracy of the characteristics of radiating structures based on chiral metamaterials with small computational resources. The results of calculating the longitudinal and transverse components of the current density distribution functions over the radiator are presented. The results were verified with the Feko software package. A good qualitative agreement of the current density distribution functions is shown. Practical application of the obtained results can be found in highly effective computer-aided design tools for the development of new-generation antennas which using in the modern communication systems, including 5G systems.

The paper proposes a high gain, metamaterial based super wideband (SWB) antenna. The SWB antenna has two inverted U slots which are responsible for two notches at 3.5 GHz and 5.5 GHz frequencies. A flower-shaped slot is etched from the radiator to obtain the SWB characteristics. The super wideband antenna has dimensions of 30×35 ×1.5 mm3 with FR4 substrate. The antenna has a frequency bandwidth of 3.1 GHz - 15 GHz for S11 < -10dB. A metamaterial unit cell is designed and simulated for permittivity and permeability characteristics. This shows a negative refractive index in the band of 2.4 GHz to 8 GHz and 8.2 GHz to 9 GHz. A 3×3 array of metamaterial cells is used as a superstrate for the improvement of the gain characteristics. The fabricated prototype SWB antenna with superstrate has measured frequency bandwidth 3.1-15 GHz with notched bands at 3.5 GHz and 5.5 GHz. The experimental and simulated results are in line with each other.

A compact T-complementary split-ring resonator (CSRR) antenna was developed. Different from traditional designs, the proposed CSRR functioned not only as a loading structure but also as a radiator....

This letter presents a filtering substrate integrated waveguide slot antenna design with multiple radiation nulls based on a double slot coupling scheme. It consists of a dual-layer cavity resonator, a slot in the first layer, and two coupling slots inserted in the middle layer. The slot in the first layer functions as the antenna radiator. This radiator is etched in the first cavity instead of the last stage of the network, resulting in two radiation nulls. A double slot coupling scheme is employed in the middle layer to not only couple the two-layer cavity resonators but also generate two more radiation nulls. Owing to these radiation nulls, the antenna features high-frequency selectivity as well as out-of-band radiation suppression level. For demonstration, the proposed filtering antenna is implemented and tested. The antenna operates at the center frequency 4.5 GHz with 15.4% (4.2–4.9 GHz) measured bandwidth. The maximum gain within the operating band is 7.5 dBi and four radiation nulls are generated. Better than 21 dB out-of-band radiation rejection level is obtained.

We solve the problem of electromagnetic positioning on the basis of two magnetic dipoles with the same center. We construct a navigation and orientation algorithm for a remote object.

Combined with the classic Chinese window grille structure, this paper proposes and designs a multiband microstrip antenna that can be used in wireless mobile terminal equipment. The antenna radiator adopts a rectangular bending structure with four loops, which increases the effective current path of the antenna radiator in a limited space, so that the overall antenna is miniaturized. The branch structure of the four-ring phase set increases the current path of the antenna, making the antenna multiband. The electromagnetic simulation software HFSS was used for antenna modeling and parameter optimization, and the influence of the feed structure, feed mode, and ground plate shape on the antenna was compared and analyzed. The test results show that the antenna can cover four bands, 0.85–1.1 GHz, 1.2–1.8 GHz, 2.40–2.7 GHz, and 5.05–6.3 GHz, and produce 6 main frequency points, 0.9 GHz, 1.3 GHz, 1.6 GHz, 2.55 GHz, 5.3 GHz, and 6.05 GHz. The antenna can cover various navigation systems, Bluetooth, WLAN, ISM frequency band, and 5G (5.725–5.825 GHz).

The results of studies of the effect of acoustic interaction in flat systems of cylindrical piezoceramic radiators with a liquid filling, due to the multiple exchange of radiated and reflected sound waves between the elements of the systems during the formation of their acoustic fields in the surrounding space to the resonance state of these systems are presented. In the computational model of the planar system the relations between the electric, mechanical and acoustic fields of the piezoceramic radiators in the process of energy transformation and their acoustic interaction during the formation of the acoustic field of the system are taken into account. The result of such interaction of the cylindrical piezoceramic radiators with their radial-symmetric electric excitation in the system is the breaking of radial symmetry of acoustic load that depends on many characteristics of the system. It is found that due to the breaking of this symmetry in mechanical fields of radiators of the system new forms of oscillations following the main one are generated, and there is an effective redistribution of energy between them which is “pumped” into radiator at the used variant of their electrical excitation only by the main form of oscillations. It is shown that this phenomenon causes appearance of number of new resonances in the oscillation spectrum of the planar system and essential changes of amplitudes and phases of full oscillation velocities of their radiators which depend on location of radiators in the planar system, wave sizes of radiators and system, physical characteristics of fluids filling the radiators, and frequency range.

This paper proposes a dual-band dual-polarized antenna which can operate at both the 1.71–2.69 GHz band (3G/4G band) and the 3.3–3.8 GHz band (5G NR band 78). The main radiator (crossed dipoles) is meticulously designed to obtain the two desired bands of interest, and the fan-shaped feeding structures are used to obtain good impedance matching. The measured low band and high band operations was 49.8% (1.69–2.81 GHz, VSWR ≤ 1.5) and 14.8% (3.32–3.85 GHz, VSWR ≤ 2), respectively. The measurement results also show that this antenna has good isolation, stable radiation pattern, and good XPD.

In this work ZrO2–SiO2 aerogels with ZrO2 content of 3, 6 and 10 mol. % in the form of transparent blocks were synthesized using the sol-gel method. The possibility of introducing ZrO2 into a SiO2 aerogel without considerable decline of the optical characteristics of the material was shown for the first time. Aerogel samples were studied by several techniques including UV–Vis, ATR-FTIR spectroscopy and nitrogen adsorption, the refractive index was determined using beam tests (“Extracted beams” of the VEPP-4M complex). It was shown that the addition of ZrO2 to SiO2 aerogel increases the refractive index without increasing of the aerogel density. For the first time, the possibility of obtaining highly transparent ZrO2–SiO2 aerogel blocks with acceptable optical characteristics for radiator in Cherenkov detectors has been demonstrated. This result makes it possible to achieve high refractive indices in the production of aerogel blocks for Cherenkov detectors to increase their performance.

The aim of this article is to describe the design, realization, and characterization of a compact, broadband, and calculable electromagnetic field source. The source has been extensively used as a traveling reference radiator in proficiency tests of radiated emission measurements. The result of its characterization has been validated by more than 500 measurements over the frequency range from 50 to 6000 MHz in semianechoic (3 and 10 m) and fully anechoic (3 m) chambers. The use of the source as a reference radiator for emission measurements could be extended to other testing facilities, such as transverse electromagnetic waveguides and reverberation chambers.

This article presents a dual-polarized Vivaldi array on a triangular lattice. The all-metal ultrawideband Vivaldi features offset radiator pairs that are precision-machined from aluminum stock as a modular tile, similar to earlier reports on more typical all-metal square-lattice Vivaldi arrays. The intent of this work is to validate the embedded element performance of the dual-polarized triangular-lattice Vivaldi, comparing one-to-one with results for a similarly sized dual-polarized all-metal Vivaldi array on a square (egg-crate) lattice, reported previously. The triangular-lattice Vivaldi array is optimally sampled for grating-lobe-free scans with a potential 15.5% reduction in element count compared to a corresponding optimally sampled square-lattice array of similar size. As such, the footprint of the manufactured triangular-lattice Vivaldi array is roughly 8% larger than the square-lattice array, yet has 7% fewer elements. Infinite array predictions are presented and shown to compare favorably with previous findings for the square-lattice Vivaldi array, noting minor performance compromises. Wideband and wide-scan simulations are validated with measurements of prototype hardware, demonstrating that embedded element performance of the triangular-lattice array correlates well with modeling predictions. All told, the triangular-lattice array has similar capability to the square-lattice Vivaldi array in a more efficiently sampled aperture.

In this communication, a high-gain substrate-integrated waveguide (SIW) filtering patch antenna with low H-plane cross-polarization (cross-pol) and controllable radiation nulls is proposed. The antenna is composed of a radiation patch integrated with three pairs of shorting pins and a single layer SIW cavity with two transverse slots. The shorting pins loaded on the patch can improve the gain and reduce the H-plane cross-pol of the antenna. The long slot on the middle layer can not only split the TE110-mode resonator into two half-mode resonators but also generate magnetic coupling between half-mode resonators and the patch. Another short slot achieves mixed electric and magnetic coupling between the left half-mode resonator and the patch that introducing controllable radiation nulls to improve the selectivity. By adjusting the parameters of the short slot, the positions of two radiation nulls can be easily controlled. Finally, one prototype filtering antenna is fabricated and measured for demonstration. Experimental results show that the proposed SIW filtering antenna achieves a high gain of 9 dBi with only one radiator and has the merit of high-frequency selectivity as well as low H-plane cross-pol of lower than −43 dB.