Back Lobe Research Articles

A High Gain Antenna with DGS for Sub-6 GHz 5G Communications

This paper introduces the design of a high-gain wideband microstrip patch antenna for sub-6 GHz 5G communication. The proposed antenna integrates a novel defected ground structure (DGS) for achieving the wide bandwidth. The ground plane uses a triangular strip inserted into the ground plane to improve the performance of the antenna. It also uses the reflective plate to concentrate the side lobes and minimise the production of the back lobe, thereby boosting the main lobe of the radiated signal and thus increasing the gain of the proposed antenna. The proposed antenna uses the FR-4 epoxy substrate with an inset feed technique in its design. The simulation and optimisation of the proposed antenna were carried out with CST Microwave Studio Suite. The antenna design is compact with a dimension of 28:03 23:455:35mm3 and a maximum gain and directivity of 6.21 dB and 7.56 dB respectively, with a radiation efficiency of about 80%. The proposed antenna operates from 4.921 GHz to 5.784 GHz, which covers the 4.9 GHz-5.8 GHz of the sub-6 GHz 5G communications spectrum. Fabricated and measured result of the antenna confirm simulated results.

Wideband and High-Gain Substrate Integrated Folded Horn Fed Open Slot Antenna

This article presents a novel substrate-integrated folded horn-fed open slot antenna with wide bandwidth and high gain for millimeter-wave (mmW) applications. The antenna has a three-layer planar structure, including a pair of open slot radiators and two substrate-integrated H-plane horns (SIHs) that are incorporated as the feed to generate quasi-TEM wave excitations. A folded SIH structure is introduced, which reduces the antenna size by 37%. To improve the gain and radiation patterns, the proposed antenna is designed with differentially fed excitations. The measured results validate that the antenna achieves a wide impedance bandwidth of 54.4% from 52.3 to 91.4 GHz and a peak gain of 16.3 dBi. Meanwhile, the radiation patterns are stable throughout the operating bandwidth with low cross-polarization, sidelobe, and back lobe levels. The proposed wideband, high-gain, planar, and low-cost antenna is an attractive candidate for mmW applications.

Ultra-Wideband Spiral Antenna with Back Lobe Reduction for Communication Systems

Spiral antennas are often used for communication applications. However, this antenna has a two-way radiation pattern. The back-lobe antenna can reduce the main lobe transmit power. This article discusses the design of a spiral antenna with a directional radiation pattern. The antenna substrate uses RO4350B with a thickness of 1.524mm and a dielectric constant of 3.66. On the antenna arms, there is a resistive load to extend the bandwidth and reduce the dimensions of the antenna. A balun is used to feed the Archimedean spiral antenna as a balanced antenna. The absorbed cavity is used to reflect the beam in an undesired direction. The simulation results show that the antenna's operating frequency is in the range of 2.5-12.5GHz for a return loss of less than -10 dB. The absorber helps suppress undesired radiation fields and reduces the back lobe of the antenna. In addition, the use of an absorber can reduce antenna gain. Therefore, the thickness of the absorber needs to be considered. The simulation results show the performance of this antenna.

Influence of the radius of a perfectly conducting cylinder on the radiation pattern of a patch antenna

In this paper, we consider the change in the directional pattern of a microstrip patch antenna located on a perfectly conducting plane and a cylinder covered with a dielectric layer. The mathematical apparatus of the Green’s tensor functions for flat and cylindrical layered metaldielectric structures is used to calculate field characteristics. The obtained results are of special interest in the design of conformal single radiators and antenna arrays located on curved surfaces that can be approximated by a cylinder, for example, the fuselage of small-sized aircraft or supports for the installation of antenna systems. It is demonstrated that the curvature of the base surface for a single element has little effect on the radiation pattern within the width of the main lobe; nevertheless, the increase in the radius of the used cylinder influences the level of the back lobe significantly.

A Constant Gain and Miniaturized Antipodal Vivaldi Antenna for 5G Communication Applications

This paper proposes a stable gain and a compact Antipodal Vivaldi Antenna (AVA) for a 38 GHz band of 5G communication. A novel compact AVA is designed to provide constant gain, high front to back ratio (FBR), and very high efficiency. The performance of the proposed AVA is enhanced with the help of a dielectric lens (DL) and corrugations. A rectangular-shaped DL is incorporated in conventional AVA (CAVA) to enhance its gain up to 1 dBi and the bandwidth by 1.8 GHz. Next, the rectangular corrugations are implemented in CAVA with lens (CAVA-L) to further improve the gain and bandwidth. The proposed AVA with lens and corrugations (AVA-LC) gives a constant and high gain of 8.2 to 9 dBi. The designed AVA-LC operates from 34 to 45 GHz frequency which covers 38 GHz (37.5 to 43.5 GHz) band of 5G applications. Further, the presented AVA-LC mitigates the back lobe and sidelobe levels, resulting in FBR and efficiency improvement. The FBR is in the range of 12.2 to 22 dB, and efficiency is 99%, almost constant. The AVA-LC is fabricated on Roger’s RT/duroid 5880 substrate, and it is tested to verify the simulated results. The proposed compact AVA-LC with high gain, an improved FBR, excellent efficiency, and stable radiation patterns is suitable for the 38 GHz band of 5G devices.

Annular Ring Ultra Wideband Antenna Integrated With Metallic via Array for IoT Applications

An annular ring microstrip antenna (ARMSA) with metallic drilled holes and a defected ground structure is proposed for ultra-wideband applications. The annular ring microstrip patch antenna is excited by the microstrip line feed. The outer radius of the annular ring was optimized in this paper to choose the resonant frequency corresponding to the highest mode. The inner radius boosts the structure’s gain. A defected conductive strip with an arc in the center increases bandwidth at the lower end, increases gain and suppresses Co and Cross-pole isolation. Incorporating a metallic via array excites and includes several closely spaced lower order modes, increasing the fractional bandwidth to 108%. The gain of the proposed configuration is 10dBi at the resonance frequency. It offers Front to back lobe ratio (FBR) of 34dB and 97% radiation efficiency. The performance of the fabricated prototype agrees well with the simulated one.

A new optimized quadrant pyramid antenna array structure for back lobe minimization of uniform planar antenna arrays

In this paper, a new optimized quadrant pyramid antenna array (O-QPAA) structure is proposed for back lobe minimization of planar antenna arrays (PAA). Based on the PAA size, it is thought to be formed of a number of concentric co-planar squared antenna arrays (SAA) or rectangular antenna arrays (RAA) placed in the X-Y plane. Initially, to construct a non-optimized QPAA, these concentric SAAs or RAAs are distributed vertically along the Z-axis with uniform vertical spacing. Thereby, the QPAA is treated as a hybrid of uniform SAAs or RAAs and a linear antenna array (LAA). However, the QPAA may have a main beam and back lobe of the same amplitude. To address this issue, the O-QPAA structure is proposed, which allows for the minimization of the back lobe while still controlling the QPAA pattern features such as side lobe level (SLL) and half power beamwidth (HPBW). The particle swarm optimization (PSO) approach is employed in this O-QPAA structure to identify the optimal values of the three main QPAA parameters, which are inter-element spacing within each SAA or RAA, vertical spacing, and the non-uniform excitations of the LAA to form the entire O-QPAA radiation pattern.

New distributed beamforming techniques based on optimized elliptical arc geometry for back lobe cancellation of linear antenna arrays

The presence of array back lobe is a major source of interference, power loss, and degrades the signal-to-interference ratio (SIR) in wireless communication systems. In this paper, new distributed beamforming techniques based on an optimized elliptical arc geometry (EAG) are proposed for back lobe cancellation of linear antenna arrays (LAA). The optimized EAG allows for flexible control of the elements' locations and initial transmission phases of their radiations, allowing them to add constructively towards the main beam direction and add destructively towards the back lobe direction. Firstly, two EAG based beamforming techniques are introduced using either a single ellipse-EAG (SE-EAG) or double ellipses-EAGs (DE-EAG). In these techniques, the back lobes are minimized by optimizing both the minor axes of the elliptical arcs and the elements' angular distributions using the particle swarm optimization (PSO) technique. While the elements' transmission energies are kept the same as that of the original LAA. For further back lobe minimization, the double ellipses-EAG with optimized energies (DE-EAG-WOE) beamforming technique is introduced, where both elements' transmission energies and positions are optimized. To verify the superiority and the possibility of practical validation of the proposed techniques, the proposed distributed array configurations based on the DE-EAG-WOE are realized using the CST Microwave Studio software package using dipole elements.

A wideband and directive metasurface FPC antenna with toroidal metal structure loading

Abstract In this paper, a novel metasurface-based Fabry−Perot cavity antenna loaded with toroidal metal structures is presented. The antenna is compact, wideband, and has high directivity and a high front-to-back ratio. The idea of the antenna is based on loading a microstrip narrow band patch antenna resonating at 4.5 GHz by a single layer metasurface superstrate and with a toroidal metal structure. The metasurface superstrate comprises a periodic array of square patch cells. Compared to conventional microstrip antenna, the front to back lobe ratio is increased from 7 to 20 dB and the directivity is increased by 7 dB. Also, the antenna impedance bandwidth is 34% which is increased four times. This is the first-ever antenna with enhanced bandwidth and directivity using a single layer of metasurface and that too made up of periodic cell array and has application as an energy harvester.

ГЕНЕТИЧЕСКАЯ ИЗМЕНЧИВОСТЬ ОЦЕНКИ ТЕЛОСЛОЖЕНИЯ КОРОВ - ПЕРВОТЕЛОК ГОЛШТИНСКОЙ ЧЕРНО-ПЕСТРОЙ ПОРОДЫ РАЗНЫХ ЛИНИЙ

Exterior assessment is important for specification of constitutional strength of an individual animal and its acclimatization ability, as well as its productive orientation. The object of our research was Holstein first-calf heifers of the black-and-white breed prevailing on the farms of Moscow region. Studies were conducted with application of linear estimation of the animal body type of 54,170 animals. Animals are divided into 5 groups depending on the lineage: Vis Back Ideal 1013415, Reflection Sovering 198998, Pabst Governer 882933, Montvik Chieftain 95679 and other lines. Most of the animals had parameters in the range of 4 ... 6 points. With greater reliability (p≤0.001) and in the course of the dispersion analysis, it was found that it affects the rump bone height, position of the quarters, the height of the back lobes, the length of the nipples, the width of the quarters and the angle of the back legs from the side (p≤0.01). The heritability of the rump bone height (0.27 ... 0.38) and milk type (0.16 ... 0.36) in almost of all studied lines was within moderate limits. A high occurrence of such constitutional defects as soft ankles (4.16 ... 13%), oblique udder bottom (1.78 ... 5.02%), high tail (2.75 ... 8.07%) and roof-like quarters (1.08 ... 3.77%) was noted in such lines of first-calf heifers as Vis Back Ideal 1013415, Reflection Sovering 198998 and Montvik Chieftain 95679. Animals of all the studied groups have high genetic correlations between the rump bone height and other parameters of constitutional assessment: Montvik Chieftain line has 95679 positive pairs 8 ( 0.63 ± 0.0032 ... 0.97 ± 0.0005) and 5 negative pairs (-0.66 ± 0.0041 ... -0.97 ± 0.0045); Vis Back Ideal 1013415 - 2 positive pairs (0.48 ± 0.0007... 0.66 ± 0.0006); Reflection Sovering 198998 - 4 positive pairs (0.41 ± 0.0009 ... 0.62 ± 0.0007); Pabst Governer 882933 - 3 positive (0.55 ± 0.0092 ... 0.74 ± 0.0071) and 2 negative pairs (-0.62 ± 0.0174). The obtained results reveal wide selection possibilities in dairy herds.

Interferometric Phase Error Analysis and Compensation in GNSS-InSAR: A Case Study of Structural Monitoring

Global navigation satellite system (GNSS)-based synthetic aperture radar interferometry (InSAR) employs GNSS satellites as transmitters of opportunity and a fixed receiver with two channels, i.e., direct wave and echo, on the ground. The repeat-pass concept is adopted in GNSS-based InSAR to retrieve the deformation of the target area, and it has inherited advantages from the GNSS system, such as a short repeat-pass period and multi-angle retrieval. However, several interferometric phase errors, such as inter-channel and atmospheric errors, are introduced into GNSS-based InSAR, which seriously decreases the accuracy of the retrieved deformation. In this paper, a deformation retrieval algorithm is presented to assess the compensation of the interferometric phase errors in GNSS-based InSAR. Firstly, the topological phase error was eliminated based on accurate digital elevation model (DEM) information from a light detection and ranging (lidar) system. Secondly, the inter-channel phase error was compensated, using direct wave in the echo channel, i.e., a back lobe signal. Finally, by modeling the atmospheric phase, the residual atmospheric phase error was compensated for. This is the first realization of the deformation detection of urban scenes using a GNSS-based system, and the results suggest the effectiveness of the phase error compensation algorithm.

Energy-Efficient Joint Wireless Charging and Computation Offloading in MEC Systems

Edge networks offer a promising solution for satisfying the increasing energy and computation needs of user devices with new data intensive services. A mutil-access edge computing (MEC) system with collocated MEC servers and base-stations/access points (BS/AP) has the ability to support multiple users for both data computation and wireless charging. We propose an integrated solution for wireless charging with computation offloading to satisfy the largest feasible proportion of requested wireless charging while keeping the total energy consumption at the minimum, subject to the MEC-AP transmit power and latency constraints. We design a novel nested algorithm to optimally solve the resulting non-convex problem in order to jointly perform data partitioning, time allocation, transmit power control and design the optimal energy beamforming for wireless charging. The proposed resource allocation scheme offers minimal energy consumption compared to other schemes while also delivering a higher amount of wirelessly transferred charge to the users. The results also show that compared to other solutions, the energy charging beams for minimum consumption have a wider main lobe, smaller side lobes, with an absence of the back lobe. Even with data offloading, the proposed solution shows significant charging performance, comparable to the case of charging alone, hence showing the effectiveness of performing partial computation offloading jointly with wireless charging.

Using EBG to Enhance Directivity, Efficiency, and Back Lobe Reduction of a Microstrip Patch Antenna

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

A WIDEBAND ANTENNA ARRAY FOR RF ENERGY HARVESTING

In this paper, we introduce a wideband antenna array for RF energy harvesting from 3G/4G and Wi-Fi. The array consists of four parallelly linked wideband antenna elements and a metallic reflector to enhance gain and suppress back lobe radiation. In measurement, the antenna array possesses a wide bandwidth spanning from 1.6 GHz to 2.5 GHz, fully cover the three harvested bands, and the high gains between 13.5 dBi and 14 dBi. The antenna is employed in a multiband rectenna for energy harvesting and placed in the ambience. The rectenna was able to collect up to 0.27 mW power.

Broadband, Beam-Steering Asymmetric Stacked Microstrip Phased Array with Enhanced Front-to-Back Ratio

The backward radiation is a critical problem that may cause breakdown of the front-end circuits that are integrated behind the antenna. Thus, antennas having high Front to Back Ratio (FBR) are required. For phased arrays, the back lobe suppression is required for all scanning angles at all frequencies of the band. In this work, a stacked patch linear array with asymmetric configuration is proposed. It is capable of scanning the beam in ±40° with less than 1.34 dB scanning loss. Due to the usage of probe-fed stacked patches as the antenna elements, impedance matching in 8-10 GHz is achieved. More than 30 dB FBR is obtained for broadside radiation. It is above 20 dB when the beam is steered to θ = 40°. This is valid for all frequencies of the band. A prototype is fabricated and measured. Higher than 38 dB FBR is observed. With its broadband, high FBR and low scanning loss, the proposed asymmetrical stacked patch phased array is suitable as radar and base station antenna.

Gain bandwidth enhancement of microstrip antenna fed half wavelength Fabry Perot cavity antenna

In this article, gain-bandwidth of microstrip antenna (MSA) fed half wavelength Fabry-Perot cavity (FPC) antenna is enhanced by modifying partially reflecting surface (PRS) and artificial magnetic conductor (AMC) surfaces. Two methods are considered to analyze the resonant condition of FPC antenna. In the first method phase correction is applied, to take into account the modification in AMC layers, while in second method the entire AMCs and PRS surface of the structure is taken as a unit cell. The proposed antenna provides S11 < −10 dB, peak gain of 17.7 dBi with gain variation < 2 dB, side lobe level < −19 dB, cross polarization level (CPL) < -16 dB and front to back lobe ratio > 20 dB over 5.66 to 6.4 GHz, which covers ISM and satellite uplink C band. The overall antenna dimensions are 2.7λ0 × 3.1λ0 × 0.5λ0; here λ0 is the wavelength in free space corresponding to 5.8 GHz, center frequency of the ISM band. The measured results agree with simulated results.

Dielectric loaded directive Vivaldi antenna considering dispersion in near and far field

A “V” slot dielectric loaded antipodal Vivaldi antenna is proposed in this article, which provides significant improvement for directivity, front to back lobe ratio and low side lobe level over the operating frequency band from 1.76 GHz to 10 GHz. Initially, the 35° upward tilted parallel slots are placed along the outer curvy conductor edges of the antenna to maintain the desired radiation performances and impedance matching. Thereafter the V slot extended dielectric slab is integrated with this design for the improvement of radiation performances and pulse spreading effect while maintaining high directivity. The antenna prototype is fabricated and tested which shows the return loss is below the 10 dB, maximum directivity is achieved at 10 GHz which is 17.5 dBi and front-to-back lobe level ratio is 29.2 dB, almost triple as compare to conventional Vivaldi antenna at 9 GHz. The measured results depicts that the highest main lobe squint angle is 2.7° at 6 GHz. In addition to this, the measured system fidelity factor (SFF) is 0.86 and 0.91 at near and far field respectively which confirms that the V slot actually reduces the pulse spreading and dispersion effect while maintaining the high directivity.

Design of Dual-Polarized Pyramidal Log-Periodic Antenna with Integrated Feed for Additive Manufacturing

A dual-polarized log-periodic antenna with 5:1 bandwidth is considered for wideband, amplitude only direction-finding applications. The proposed system is comprised of two identical, orthogonal, sets of trapezoidal log-periodic arms. The arms’ inclination from planar facilitates reduced back lobe radiation to improve directivity and efficiency once absorber is introduced. One arm of each polarization set contains a variable radius coaxial shell to achieve impedance matching such that the system impedance at the base of the antenna is matched to 50 ohms. Analysis and design for the 3d printed direction-finding antenna system is accomplished using a commercial off the shelf (COTS) finite element method (FEM) solver.

Gain enhancement by utilizing hexagonal reflector based optimized textile antenna

In this article, a square patch antenna with reflector is fed by inset feed for wearable applications in the ISM band (2.45 GHz) Using Jean's substrate with a 3 mm thickness and dielectric constant of 1.7. In this article, the design of the Textile patch antenna is optimized using the Oppositional Particle Swarm optimization (OPSO) algorithm to resonate at 2.45 GHz. The PSO is a population-based algorithm designed to tackle various optimization problems. The performance deteriorates significantly when the optimization problems are to be subject to noise . The flexible and textile antennas have taken a lot of attention due to their application in wearable systems and their testing in real-work conditions. The major advantage of the proposed system is minimizing the back lobe and enhances the gain. Usually, Antenna parameters such as reflection coefficient, Voltage standing wave ratio, Gain & Directivity are measured using CST software.

Design and analysis of Jeans based Wearable monopole antenna with enhanced gain using AMC backing

A monopole antenna with enhanced gain, low Specific Absorption Rate (SAR) and low profile backed with an artificial magnetic conductor (AMC) for wireless communications is designed and presented in this article. This antenna presents AMC design, which isapplicableto reduce the SAR for the portion of the EM waves where electromagnetic pollution is commonly observed. To reduce the radiation of the back lobe and to improve the antenna gain, AMC is designed and backed under the monopole antenna. The antenna resonates in a single band which is from 2.38GHz to 2.44GHz with the reflection coefficient of 2.41Ghz. With the obtained band, the proposed model can be utilisedfor wearable applications.