Radiation Pattern Of Antenna Research Articles

An Effective Method for Antenna Radiation Pattern Reconstruction Based on Phaseless Measurement in a Reverberation Chamber

It has been shown that the angular correlation of the antenna can be obtained by rotating it in a reverberation chamber (RC) and the radiation pattern of the antenna under test (AUT) can be reconstructed from the measured correlation coefficients using spherical wave decomposition. However, the correlation coefficient needs to be obtained by measuring the complex-valued S-parameters in an RC, which is no longer applicable to active antenna tests where the phase information is unavailable. To solve this problem, we propose an antenna radiation pattern reconstruction method based on phaseless measurement in an RC. In this method, the power correlation coefficient of AUT is calculated using the signal amplitude received by the antenna at different angles. According to the relationship between complex correlation coefficient and power correlation coefficient of the AUT, the nonlinear least squares method is used to reverse the spherical wave coefficients and reconstruct the antenna radiation pattern. Simulations and measurements are carried out in RC and anechoic chamber, which demonstrated the feasibility and applicability of the proposed method.

Optimization features of an aperture antenna with field variable-phase distribution

The solution of a number of tasks at maximum ranges in a wide sector of angles requires the use by radio engineering systems of an antenna with a quasi-sector directional pattern, the formation of which is provided by an variable-phase distribution of excitation sources (currents or fields). Taking into account the ambiguous influence of many parameters of such a distribution on the shape of the realized radiation pattern, the traditional optimization criteria for such an antenna are unacceptable. The possibilities and criteria of parametric optimization can be determined using numerical methods of mathematical modeling. In order to solve the problem of parametric optimization of an aperture microwave antenna with a quasi-sector radiation pattern and to select a criterion that allows achieving the best design solution of the projected antenna in this sense, its mathematical model has been developed. It is proposed to use a complex quality criterion for optimization in a uniform approximation of antennas with variable-phase field distribution in the aperture. The constructed mathematical model of a microwave antenna describing the quasi-sector radiation pattern and the corresponding field distribution in its aperture is presented, which makes it possible to determine the controlled parameters that ensure the achievement of a given optimization criterion. The determining influence of the fraction and amplitude of the antiphase section in the field distribution on the main parameters of the radiation pattern is shown. The results of mathematical modeling indicate the possibility of controlling the parameters of the quasi-vector radiation pattern of the aperture antenna and achieving a given criterion for its optimization. The results obtained can be recommended for practical use in the design of aperture antennas with variable-phase distribution of field.

Compact Dual-Band and Dual-Polarized Base Station Antenna With Shared-Dipole Elements

In this letter, a compact dual-band and dual-polarized base station antenna with the LB and HB shared-dipole elements is presented. The proposed antenna consists of a low band (LB) element and a high band (HB) element with an embedded structure. By sharing the arms of the LB antenna dipoles, the antenna planar size is miniaturized greatly. To reduce the mutual effect between the LB and HB antenna elements, the slots on the LB arms are introduced, resulting in baffles on the four sides. And then, the baffles can also be optimized to stabilize the radiation patterns of the HB antenna. The antenna prototype is fabricated and measured for verification. Results show that the antenna can achieve fractional bandwidths of 40.2 % for the LB element and 45.5 % for the HB element while the in-band return losses are better than 15 dB, covering the frequency range 0.69-1.02 GHz and 1.70-2.71 GHz for 2G/3G/4G applications. Meanwhile, the measured port isolations are larger than 33 dB and 38 dB for the LB and HB elements, respectively.

Simulations on the effects of an optimized bowtie dipole antenna with an adaptive FIR filter

In the evolution of technology through the years, antennas are use in varying wireless systems have been in demand. Antennas play a great role in transmitting and receiving signals. As its application is heavily used in many days to day activities, it is important to create a cost-efficient and quick way to analyze its performance, characteristics, and relationship to different variables. As many radiation pattern acquisition devices are expensive, this simulation proposes a quick, reliable, and cost-friendly way to simulate 2D patterns in the E-plane and H-plane of a bowtie dipole antenna with an adaptive finite impulse response (FIR) filter. Through this study, the software MATLAB will be utilized to successfully simulate the radiation patterns of antennas with varying lengths. With the use of MATLAB toolboxes, the researchers aim to be able to compare different antenna lengths and determine the relationship and effect of it in the obtained 2D radiation pattern. If this method is successful various antenna applications may be implemented in the future with the use of 2D radiation pattern results.

Shaped Omnidirectional Reflector Fed by a Dielectric Lens Associated with a Coaxial Feed Horn

The paper explores an omnidirectional antenna configuration composed of a reflector fed by a shaped dielectric lens associated with a coaxial TEM horn. A simple formula describes the lens shape obtained by applying Fermat’s principle to control the rays’ caustic emerging from the dielectric interface. Based on geometrical optics (GO) principles, a synthesis technique defines the reflector shape to control the antenna radiation pattern in the vertical plane. Concatenated conic describes the reflector generatrix. The study employs a full-wave analysis to validate the designs and explores the proposed configuration to attend two distinct far-field specifications.

A compact frequency reconfigurable beam switching antenna based on a single‐layer FSS

AbstractA compact frequency reconfigurable beam switching antenna based on a single‐layer frequency selective face (FSS) is proposed in this paper. The proposed antenna consists of a dual‐band dipole antenna and a single‐layer FSS with hexagonally arrangement. The omnidirectional radiation pattern of the dipole antenna designed as a radiation source and surrounded by the FSS can be converted into directional radiation pattern sweeping along the entire azimuthal plane at two single frequency of 2.4 or 5 GHz. The frequency selection is achieved by controlling the diode state of the FSS unit, and the beam switching is realised by a specific combination of electromagnetic wave reflection or transmission from the hexagonal FSS. The novelty lies in applying the hexagonal arrangement to a dual single‐frequency single‐layer FSS unit. This will not destroy the reflection or transmission characteristics of the FSS unit, but also contribute to reduce the antenna size and achieve a low cost. To validate the design, a prototype is fabricated and measured. The single‐layer FSS antenna with a volume of 57 mm × 57 mm × 58.5 mm can be scanned in 12 steps along the azimuth plane at 2.4 and 5 GHz, respectively.

Metamaterial physical property utilized antenna radiation pattern deflection for angular coverage and isolation enhancement of mm-wave 5G MIMO antenna system

This paper proposed metamaterials (MMs) inspired radiation pattern deflected multiple input multiple outputs (MIMO) antenna systems for 5G applications. The MMs structure achieves high gain and wide angular coverage to overcome attenuation in electromagnetic (EM) wave propagation paths. Besides, the MMs structure provides high isolation in the MIMO antenna system. The deflection mechanism is attained using two different MMs unit cells of circular splits ring resonator (CSRR) and concentric circular ring resonator (CCRR). The MMs unit cells are configured in three different arrangements to achieve negative, normal and positive deflection radiation patterns. The −10 dB impedance bandwidth of 3.4 GHz (27.5–30.9 GHz) with a gain improvement of 2–3 dBi is obtained for all three deflection configurations. The noticeable novelties of the proposed MIMO antenna system are achieving both negative and positive deflection of 30° and significant isolation enhancement at the entire operating frequency.

Design of NULLMAC Protocol for Mobile Ad Hoc Network Using Adaptive Antenna Array

Usually, omnidirectional radiation pattern antenna is used in the mobile ad hoc network (MANET) which causes neighbor node interference, consumes more power, and supports only limited range of transmission. To overcome these problems, smart antennas are used. A lot of medium access control (MAC) protocols are proposed using smart antennas. Existing works addressed various problems such as hidden terminal problem, hidden beam problem, deafness of nodes, and head of line blocking problem. However, certain factors including determination of weight vector and conveying it to the neighbor nodes for distortion-free transmission are not considered. In this study, nullifying MAC (NULLMAC) framework is proposed using an adaptive antenna array (AAA) for improving network performance in MANET. NULLMAC framework uses channel information for achieving high throughput and spatial reuse through integrated physical and MAC layer. Before the transfer of data packets, the receiver initially determines its weight vector and conveys it to the transmitter through control packets. Then, the transmitter computes its weight to nullify the dynamic receivers present in the neighborhood region to find the desired receiver. Beamformer weights are determined through channel coefficients between a transmitter-receiver pair to establish distortion-free transmission. Extensive simulations are performed using OPNET integrated with MATLAB. NULLMAC framework achieves 27.22% more throughput and 40.46% increase in signal-to-noise ratio.

Dual-Band Dual-Polarized Antenna Using a Simple Radiation Restoration and Decoupling Structure

This letter presents a simple structure dual-band dual-polarized antenna. The higher-band (HB) antenna is located coaxially under the lower-band (LB) one to save the installation space. The blocking effects of the LB antenna seriously deteriorate the HB antenna's radiation patterns. To solve this problem, we first introduced four stacked patches to restore the radiation performance. Unfortunately, using the stacked patches, the isolation between the LB and HB antennas reduces from about 25 to 20 dB. Then, we introduced four C-shaped metal strips as the decoupling structure and the isolation improves from 20 dB to more than 30 dB within a wideband. These stacked patches and metal strips are printed on top and bottom sides of the LB antenna substrate and therefore no extra substrate layer is needed. For demonstration, a prototype of the dual-band antenna operating at 1710–2690 MHz (LB) and 4200–5000 MHz (HB) is implemented. Normal directional radiation patterns are obtained with stable in-band gains of 7.5 and 9.5 dBi. Better than 33 dB measured isolation between the LB and HB antennas is realized.

Analysis of a Low-Earth Orbit Satellite Downlink Considering Antenna Radiation Patterns and Space Environment in Interference Situations

This paper investigates a low-Earth orbit (LEO) satellite downlink for high-speed data communication in interference situations. A choke ring horn type antenna is used as the data transmitting antenna with an isoflux pattern in the LEO satellite, which has a beam coverage of ±51.6° and a bore-sight gain of 4.4 dBi at 8 GHz. The receiving antenna on the ground station is a parabolic type antenna with a diameter of 11.3 m, and it has a half-power beam width (HPBW) of 0.2° with a maximum gain of 59 dBi at 8 GHz. The jamming-to-signal ratio (J/S) is calculated assuming that the LEO satellite transmits signals to the ground station, and an elevation angle of the interference source varies from 0° to 90° at an altitude of 10 km. Applying antenna characteristics, such as HPBWs and side lobes, to the calculated space wave path loss makes it possible to predict the J/S results according to the location of the interference source and the satellite. The results show that it is necessary to consider the space environment to accurately analyze the LEO satellite downlink, especially at the low elevation angle of the satellite.

An ultra‐wideband high gain antenna with embedded sleeves and hexagonal cavity

AbstractRadar detection and imaging systems need ultra‐wideband, high‐gain antennas to improve depth resolution and detection range. This paper proposes an ultra‐wideband high gain differential patch antenna having a peak gain of 12.9 dBi and an average gain of 11.3 dBi in the bandwidth from 7.2 and 26 GHz. Two sleeves are added around the feeding probes to attain ultra‐wideband impedance matching that is explained with an equivalent circuit. A hexagonal cavity with two M‐shaped cutouts improves the gain in the broadside direction by redistributing the current and reshaping the antenna's radiation patterns at different frequencies. The antenna's measured S‐parameter validates the design and confirms it has an ultra‐wide bandwidth. The ultra‐wide bandwidth along with the high gain values make the antenna a promising candidate for high‐resolution radar systems.

A Flexible Bi-Stable Composite Antenna with Reconfigurable Performance and Light-Responsive Behavior

An integrated solution providing a bi-stable antenna with reconfigurable performance and light-responsive behavior is presented in this paper for the first time. The proposed antenna includes a radiation layer with conductivity, which is integrated onto the bi-stable substrate. First, the effect of the radiation layer material and substrate layer parameters on antenna performance was studied. The experiment showed that an antenna with CNTF has a wider impedance bandwidth than one with CSP, namely 10.37% versus 3.29%, respectively. The resonance frequency increases gradually with the increase in fiber laying density and fiber linear density. Second, the influence of state change of the substrate layer on the antenna radiation pattern was studied. The measured results showed that the maximum radiation angle and gain of states I and II are at 90°, 1.21 dB and 225°, 1.53 dB, respectively. The gain non-circularities of the antenna at states I and II are 4.48 dB and 8.35 dB, respectively, which shows that the antenna has good omnidirectional radiation performance in state I. The display of the array antenna, which shows that the array antenna has good omnidirectional radiation performance in state A, with gain non-circularities of 4.20 dB, proves the feasibility of this bi-stable substrate in reconfigurable antennas. Finally, the antenna deforms from state I to state II when the illumination stimulus reaches 22 s, showing good light-responsive behavior. Moreover, the bi-stable composite antenna has the characteristics of small size, light weight, high flexibility, and excellent integration.

Study of the Radiation Pattern and Frequency Response of a Short Linear Antenna Surrounded by Discharge Tubes for the Development of Rapidly Adjustable Wideband Antenna Systems

Plasma antenna systems consisting of discharge elements have great practical application prospects due to their ability to quickly adjust parameters over a wide range. In this work, the radiation patterns of a 30 mm long linear antenna surrounded by 16 standard T8 fluorescent lamps were measured by using a spectrum analyzer with a tracking generator. The radiation pattern of the system is measured by connecting the output of the spectrum analyzer tracking generator to a linear antenna and connecting the input of the spectrum analyzer to the receiving broadband horn antenna. The work features experimental measurements over a wide frequency range of 0.5 to 1.5 GHz and a wide discharge with current values from 35 to 200 mA. The specific frequency band and uniquely selected geometry allowed for the investigation of both the in-phase and out-of-phase antenna modes, while some modes were found to have a narrow directional radiation pattern, within 50 degrees, with a beam width of −3 dB. The parameters of the gas-discharge plasma were also evaluated using drift theory, as well as using the microwave transmission of the 20 GHz signal. The electron density value corresponding to the used discharge currents was approximately from 4 × 1011 to 7 × 1010 cm−3.

Design and Simulation of a Square Loop Antenna for 920 MHz

This study describes design and simulation of a loop antenna. A square loop antenna is designed for 920 MHz. The loop antenna is then modelled and simulated using 4NEC2 electromagnetic (EM) modeling software. 4NEC2 is a completely free numerical electromagnetic modeling code. It is based on method of moments technique to solve electromagnetic boundary value problem. The 4NEC2 simulation of the loop antenna design predicted antenna resonant frequency to be 920 MHz, Return Loss bandwidth of 130 MHz and input impedance of 50.14 -j0.30 Ohm. The antenna radiation pattern is then simulated at 920 MHz. The Return Loss, VSWR, Input Impedance and Radiation Pattern of the antenna predicated by 4NEC2 simulation are studied for the possible development of copper or aluminium tube based loop antenna.

Broadband Magnetoelectric Dipole Filtering Antenna for 5G Application

A magnetoelectric (ME) dipole filtering antenna with high out-of-band suppression level and high selectivity is proposed in this letter. The intrinsic radiation null of the traditional ME dipole antenna is used, which produces a good filtering response at the edge of the lower passsband. A pair of vertical parasitic metal planes are introduced between the shorted walls and fed through slot coupling, which can be equivalent to an additional magnetic dipole. The radiated electric field of the magnetic dipole is opposite to that of the original antenna at higher frequency, forming a wide stopband radiation null, which greatly improves the high-frequency stopband suppression level of the antenna. Furthermore, a pair of T-shaped coupling stubs are inserted between the shorted wall and electric dipole, producing another radiation null with high roll-off rate at higher frequency. The measurement results show that the −10 dB impedance bandwidth of the proposed antenna is 49.4% (3.2–5.3 GHz). Its low-frequency stopband suppression level is greater than 16.6 dB and high-frequency stopband suppression level is greater than 26.0 dB. Moreover, the antenna radiation pattern is stable and symmetrical in the whole operating passband, and the filtering response is desirable.

A Compact 3-D Multisector Orientation Insensitive Wireless Power Transfer System

The power conversion efficiency (PCE) in wireless power transfer (WPT) degrades due to angular misalignment between the transmitter (Tx) and the rectenna (Rx) along the azimuth plane. Therefore, a compact 3-D multisector orientation insensitive WPT system is proposed to address this problem. The optimal number of sectors ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N=8$ </tex-math></inline-formula> ) is determined analytically using patch antenna design equations to mitigate the effects of angular misalignment. In addition, conditions on the receiver antenna radiation pattern are investigated to enhance the performance of the WPT system. Furthermore, the observed conditions are utilized for designing a high gain WPT system at 5.8 GHz with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N=8$ </tex-math></inline-formula> sectors. The proposed WPT system provides uniform power harvesting capability in the azimuth plane and 51.2% higher power harvesting capacity than the patch antenna WPT system.

Fast 3D ground penetrating radar simulations for glaciers

Modeling ground penetrating radar (GPR) reflection data on glaciers with methods that require the discretization of the full subsurface domain is extremely computationally expensive because of the combination of a large domain size and the comparatively short wavelength of the signal. To address this issue, we build on and extend a previously proposed approach based on the assumption of a homogeneous background medium (ice) in which various scattering objects (e.g., crevasses, channels, boulders) are embedded far from each other such that multiple scattering can be ignored. The glacier bed, below which no scatterers are assumed to exist, represents the lower limit of the modeling domain. With this method, the two-way propagation of the radar waves through the ice is simulated in a semi-analytical way, whereby scattering surfaces are represented with a set of planar elements of different electric and reflective properties, allowing a wide range of objects to be simulated. As we also take the antenna radiation pattern at the air-ice interface into account, this simple algorithm is able to produce realistic 3D GPR data in a fast and memory efficient way. In this study, we validate the presented algorithm with an analytical solution for a layered model, and we simulate radar data for a model of the Otemma glacier in Switzerland featuring a realistic topography of the glacier bed and a subglacial channel.

Design and analysis of microstrip transceiver array antennas with the function to suppress beam deflection for 77 GHz automotive radar

A microstrip transceiver array antenna with high beam pointing accuracy is designed for automotive radar. Considering the influence of the lossy conductor on the excitation current, the beam deflection problem formed by the passive microstrip series-feed linear array is analyzed and solved. Compared with the traditional microstrip series-feed linear array, the microstrip series feeder array designed in this paper has good beam pointing accuracy. A power divider based on substrate-integrated waveguide (SIW) and microstrip line (MSL) with Chebyshev amplitude distribution(applied to the transmit array antenna) and binomial amplitude distribution(applied to the receive array antenna), respectively, is designed as the feeding network of the linear array. The fabrication and measurement of the prototype transceiver array antenna are completed to verify its beam directivity. The simulation and measurement results show that the E-plane main beam of the transceiver array antenna radiation pattern has good pointing accuracy, which makes the detection accuracy of the automotive radar significantly improved.

Design of ultra-wide band dual-polarized quad ridged horn antenna for obstacle penetrating radar imaging applications

In this study, a high-gain and dual-polarized Quad Ridged Horn Antenna (QRHA) is proposed and designed to be used in Obstacle Penetrating Imaging Radar (OPIR) applications. The quad ridged design is developed and then optimized by using the antenna design simulator software; CST Microwave Studio. The antenna parameters including the center frequency, frequency bandwidth and the antenna radiation pattern beam width are considered based on the requirements of OPIR applications. The final design is obtained for the center frequency of 2.785 GHz with a -10 dB bandwidth of at least 2.5 GHz. The final designed QRHA is able to provide a gain of 12.4 dB with a beam width of 36ᵒ at the center frequency of 2.785 GHz.

Antennas for Licensed Shared Access in 5G Communications with LTE Mid- and High-Band Coverage.

Two novel antennas are presented for mobile devices to enable them to access both licensed shared access (LSA) bands (1452-1492 and 2300-2400 MHz) and all the long-term evolution (LTE) mid (1427-2690 MHz) and high (3400-3800 MHz) bands, together with the GSM1800, GSM1900, UMTS, and 3.3 GHz WiMAX bands. These antennas do not require any passive or active lumped elements for input impedance matching. One of them is a dual-band antenna and the other is a wideband antenna. Both antennas have high efficiency in all the LSA bands, as well as the mid- and high-LTE bands, and nearly omnidirectional radiation patterns in the mid band. In the high band, the radiation patterns of the wideband antenna are less directional than those of the dual-band antenna. The wideband antenna was fabricated and tested and the measurements demonstrated that it had good wideband performance in a wide frequency range from 1.37 to 4 GHz, covering all the above-mentioned bands.