Antenna Length Research Articles

Theoretical and experimental investigations on optimization of the received power of a monopole antenna

Antenna is an essential component of telecommunication devices. Recently, the antenna has been used as a receiver in the rectenna solar cells as well as a vital component of cellular mobile telecommunications. The power of the received signal may depend on the physical shape of the monopole receiving antenna. The optimization of antenna’s geometry is essential to improve the antenna performance as a receiver. It is widely accepted that the physical length of the monopole antenna; with one fourth of the incident wavelength; possesses an optimal efficiency. In the current study, a power equation based on a recently modified electromagnetic (EM) wave theory has been derived. The proposed formula has been used to calculate the optimum length of the monopole antenna to optimize the received power by the antenna. The angle between the direction of the antenna’s plane corresponding to the direction of the propagation of the EM wave has been considered. some experimental investigations have been considered to confirm our theoretical investigations. In our experiment, the output voltage has been considered as a good indication of the harvested energy of the monopole antenna.

Graphene-Controlled Reconfigurable Patch Antenna Using Shorting Elements

This paper reports the design of a patch antenna that uses of graphene-based shorting elements to implement advanced functionalities, such as multi-band and beam-steering, which make it extremely attractive for the future Fifth-Generation (5G) wireless networks. The proposed structure has 36.75×29.25 mm2 size and it has been designed on a Rogers RT/duroid 5880 substrate, 1.58 mm thick. It is composed by an external slotted rectangular patch that contains an internal circular shape. The internal shape is separated from the external one by a circular slot but it is linked to it by four copper bridges short-circuited to the underlying ground plane through a thin metal pin, one for each bridge. It has been shown that the multi-band and the beam-steering functionalities are strongly affected by the geometric location of the shorting pins. By controlling the connection of the bridges perpendicular to the antenna length, the direction of the antenna main lobe can be changed. By using the Finite Element Method (FEM), the geometric location of the shorting pins has been optimized so that the antenna resonates at 3.5 GHz frequency, exhibiting a 6.6 dBi maximum gain and a -17.55 dB S11 parameter. Moreover, by controlling electronically the connection of the shorting elements using graphene foils, three distinct beams, steering between -22 to +22 degrees, have been obtained. The beams show about 1.4 dBi theoretical antenna gain using graphene foils with 20 Ω/sq sheet resistance.

Highly efficient optical antenna with small beam divergence in silicon waveguides.

Optical antennas are key components in optical phased arrays for light detection and ranging technology requiring long sensing range and high scanning resolution. To achieve a narrow beam width in the far-field region, antenna lengths of several millimeters or more are required. To date, such long antennas have been impossible to achieve in silicon waveguides because currently demonstrated technologies do not allow accurate control of grating strength. Here, we report on a new type of surface-emitting silicon waveguide with a dramatically increased antenna length of L=3.65mm. This is achieved by using a subwavelength metamaterial waveguide core evanescently coupled with radiative segments laterally separated from the core. This results in a far-field diffracted beam width of 0.025°, which is a record small beam divergence for a silicon photonics surface-emitting device. We also demonstrate that by using a design with L-shaped surface-emitting segments, the radiation efficiency of the antenna can be substantially increased compared to a conventional design, with an efficiency of 72% at the wavelength of 1550 nm.

Effect of Induced Electromotive Force on a VLF Linear Antenna in an Anisotropic Plasma

In this article, the effect of an induced electromotive force (EMF) on the electrical characteristics of a linear antenna in an anisotropic ionosphere over a very low-frequency (VLF: 3–30 kHz) range is investigated. By establishing a technically sound mathematical model of a linear antenna with a motional status relative to the geomagnetic field, the induced EMF effect on the current distribution and input impedance of a linear antenna is first systematically analyzed and quantified. A 3-D kernel function is obtained to match the EMF generated on an arbitrarily oriented antenna. Computations show that as the dip and azimuth angles of an antenna vary in a wide range, the fluctuations on the input impedance always remain within 10%, with the change mainly reflected on the real part. The discrepancy caused by an induced EMF will be more significant when the antenna length reaches 1 km, which should not be ignored for long antennas. This analysis aims to mitigate the undesired effects led by an induced EMF and may provide heuristic support for practical schemes of VLF space-borne applications.

Horn Antenna With Miniaturized Size and Increased Gain by Loading Slow Wave Periodic Metal Blocks

An H-plane horn antenna with miniaturized size and increased gain is reported, which is realized by loading slow wave structures (SWSs) inside the shortened horn cavity. The SWSs in the form of periodic metal blocks can decelerate the phase velocity of the electromagnetic wave traveling to the radiating aperture. So the phase difference between the center and the edges of the aperture enlarged by the shortened longitudinal dimension can be compensated, and the longitudinal length of the horn antenna is significantly reduced. Meanwhile, uniform magnitude distribution of electric fields on the aperture is achieved by cleverly designing the heights of embedded blocks. Thus, the realized gain and aperture efficiency are maximized. The proposed horn antenna is easily fabricated by standard mechanical manufacture process. The longitudinal length of the prototype is 33.3% less than the original horn antenna with the same aperture size. Moreover, the average gain is 1.7 dB higher than the original horn, while maximized aperture efficiency up to 80.7% is achieved.

DC and Low‐Frequency Electric Field Measurements on the Parker Solar Probe

AbstractThe Parker Solar Probe successfully makes electric field measurements over the frequency range of DC‐100 Hz, thanks to the remarkable symmetry of the antennas with respect to sunlight and the mostly radial magnetic field. Calibration of the electric field measurement is described. Sampled electric and magnetic field data are utilized to determine wave modes of whistlers and Alfven‐ion‐cyclotron waves. In the course of such determinations, the electric field effective antenna length was found to vary with frequency from ~1 m at low frequencies to essentially the antenna half‐geometric length of 3.5 m above 20 Hz. Properties of the low‐frequency electric field power as functions of frequency and radial distance are determined. There is a plateau in the electric field power spectrum above ~10 Hz, which is due to the power in waves exceeding the turbulent cascade power above that frequency. This wave power decreases by one to two orders of magnitude from 35 to 50 solar radii.

Solar Wind Electron Parameters Determination on Wind Spacecraft Using Quasi‐Thermal Noise Spectroscopy

AbstractQuasi‐thermal noise (QTN) spectroscopy has been extensively used as an accurate tool to measure electron density and temperature in space plasmas. If the antenna length to radius ratio is sufficiently large, a typical measured spectrum clearly shows a resonance at the electron plasma frequency and a lower frequency plateau that quantify the electron distributions. The Wind spacecraft, with its long, thin antennas, is considered the mission par excellence for the implementation of the QTN method. However, a major issue in applying QTN spectroscopy is contamination from signals other than the ubiquitous plasma noise in the vicinity of plasma frequency, affecting the measured spectra and confusing their physical interpretation. In this work, we present a new method for selecting the observations of uncontaminated QTN, distinguishing it from other plasma and spacecraft effects. The selected measurements are used to obtain accurate values for both thermal and suprathermal electron parameters. Testing of the method on 1.5M observations under various conditions in the solar wind, including slow and fast wind and solar transients, confirms the reliability and accuracy of the method with no systematic flaws.

Compact Dual-Polarized Corrugated Horn Antenna for Satellite Communications

In this article, a structure and design procedure of a novel compact dual-polarized corrugated horn antenna with high gain and a stable phase center for satellite communication is presented. The antenna incorporates an ortho-mode transducer (OMT), a mode converter, and a corrugated structure. The compact OMT section is designed to be fed by standard WR-75 waveguides. The proposed compact design utilizes only ten corrugated slots to yield a symmetric radiation pattern. The antenna impedance bandwidth (VSWR < 1.5) is 10.2 to 15 GHz. Furthermore, the antenna exhibits 14–17 dBi gain, a constant 30° half-power beamwidth (HPBW) radiation pattern, and less than 9 mm phase center variation over the operating frequency range. The aperture diameter is 7 cm and the total antenna length is 15 cm. Due to the aforementioned features, the proposed antenna is suitable as the feed reflector for both uplink and downlink satellite communications. The design is numerically and experimentally validated.

Study on Impedance Matching of 2.4 GHz Dipole Antenna

Understanding on matching impedance between feedline and load is important in many aplication. Theoritically, matching impedance can be calculated easily if charateristic impedances both load and line is known. Practically, when we do impedance matching at certain frequency we face a problem if the impedance of the feedline and antenna are unknown. by using vector network analyzer and anechoic chamber we tried to study and to approach the impedance match through measurement of return loss, VSWR, and antenna radiation pattern. The results of studies have shown that adjusting dipole antennas to lines can be done by optimizing antenna and lines length and subsequently optimizing the use of balun. In this reasearch we optimized 2.4 GHz dipole antenna and matched it to feedline by using bazooka and balun 1 : 1. To achieve good matching, the antenna length is 0.35 λ and the feedline length multiplies 0.5 λ. The length of the bazooka and balun for the best impedance adjustment are 0.25 λ and 0.2λ.

Analysis of the Envelope Correlation Coefficient of MIMO Antennas Connected with Suspended Lines

Inserting a suspended line is a widely used technique to reduce the envelope correlation coefficients (ECC) of multiple-input multiple-output (MIMO) antennas, but its ECC reduction mechanism has not been carefully investigated so far. In this paper, MIMO antenna pairs connected with different suspended lines were evaluated using a full-wave simulation and measurement results. We calculated the surface current density at the center of the suspended line inserted between the antenna elements and found that the derivative of the surface current density was closely related to the ECC values. Furthermore, parametric studies showed that the suspended line length determines the ECC reduction bandwidth of the MIMO antenna, and the antenna length controls the ECC minimum frequency point. These guidelines provide useful insights into designing a low ECC MIMO antenna employing a suspended line.

Plasma Waves in Space: The Importance of Properly Accounting for the Measuring Device

AbstractElectric fields are generally measured or calculated using two intuitive assumptions: (1) the electric field equals the voltage divided by the antenna length when the antenna is electromagnetically short (2) the antenna responds best to electric field along its length. Both assumptions are often incorrect for electrostatic fields because they scale as the Debye length or as the electron gyroradius, which may be smaller than the antenna length. Taking into account this little‐known fact enables us to complete or correct several recent papers on plasma spontaneous fluctuations in various solar system environments.

Design and optimisation of a novel structure capacitive RF MEMS switch to integrate with an antenna to improve its performance parameters

In this study, a step-down structured switch is designed and compared with and without optimised dimensions to increase the isolation and to lower the pull-in-voltage with respective electromechanical and electromagnetic characteristics. The optimised switch is designed to operate only in K-band frequencies with the high isolation of -54.17 dB at the centre frequency of 22 GHz. The antenna using MEMS switch exhibits a frequency shift of 1.5 GHz from the first case to the second case and 7.4 GHz in the third case due to change in radiating length of patch antenna operating at different ON/OFF combinations of switches whereas the antenna with PIN diode shifts the frequency approximately same, but the low isolation of PIN diode makes it less immune to noise.

SIMULASI ANTENA DIPOLE ½ λ DENGAN FREKUENSI KERJA 128,4 MHz UNTUK RADIO PEMANCAR ATIS MENGGUNAKAN SOFTWARE SIMULASI DI BANDAR UDARA INTERNASIONAL HUSEIN SASTRANEGARA BANDUNG

VHF telecommunications radio equipment, especially ATIS equipment is equipment used to inform information around the airport, such as weather, taxiways, runaway, etc. ATIS equipment works on frequencies between 118-137 MHz. The problem that arises is in the ATIS equipment that is the lack of antenna beam coverage on the ATIS radio transmitter, which is &lt;100 NM, while the normal ATIS beam range is in the range of 150-200 NM. The author simulates dipole antenna ½ λ using the CST studio SUITE software application and compares the results of the simulation with the antenna specifications on the current ATIS equipment. Antenna simulation is done by making antenna dimensions and calculating the wavelength parameters, antenna length, antenna gap width, then the simulation results with the antenna length of 1040 mm and a gap of 5.545 mm, and a diameter of 3 mm, the results obtained are VSWR of 1.51 and return loss of -13,804, with a bandwidth of 12.13 MHz. These parameters were compared with the ATIS equipment antenna specifications at Bandung Husein Sastranegara International Airport and there was an increase in parameters after simulating.

First In Situ Measurements of Electron Density and Temperature from Quasi-thermal Noise Spectroscopy with Parker Solar Probe/FIELDS

Abstract Heat transport in the solar corona and wind is still a major unsolved astrophysical problem. Because of the key role played by electrons, the electron density and temperature(s) are important prerequisites for understanding these plasmas. We present such in situ measurements along the two first solar encounters of the Parker Solar Probe, between 0.5 and 0.17 au from the Sun, revealing different states of the emerging solar wind near the solar activity minimum. These preliminary results are obtained from a simplified analysis of the plasma quasi-thermal noise (QTN) spectrum measured by the Radio Frequency Spectrometer (FIELDS). The local electron density is deduced from the tracking of the plasma line, which enables accurate measurements, independent of calibrations and spacecraft perturbations, whereas the temperatures of the thermal and suprathermal components of the velocity distribution, as well as the average kinetic temperature, are deduced from the shape of the plasma line. The temperature of the weakly collisional thermal population, similar for both encounters, decreases with the distance as R −0.74, which is much slower than adiabatic. In contrast, the temperature of the nearly collisionless suprathermal population exhibits a virtually flat radial variation. The 7 s resolution of the density measurements enables us to deduce the low-frequency spectrum of compressive fluctuations around perihelion, varying as f −1.4. This is the first time that QTN spectroscopy is implemented with an electric antenna length not exceeding the plasma Debye length. As PSP will approach the Sun, the decrease in the Debye length is expected to considerably improve the accuracy of the temperature measurements.

Design and Analysis of Moisture Content of Hevea Latex Rubber Using Microstrip Patch Antenna with DGS

A microstrip patch sensor is designed and analysis for determination of moisture content in Hevea Rubber Latex. The microstrip patch sensor was designed to operate at microwave frequency range 2.8GHz, 7.8GHz and 8.8GHz on FR4 substrate with 4.4 permittivity and 1.676mm thickness. The width and length of the rectangular patch antenna was 30mm and 35mm, respectively as well as defected ground structure in the ground and microstrip line feed used because of easy to feed and low spurious feed radiation with the simulated by using the CST software. The actual values of moisture content will be obtained by using standard oven drying method and measured by the vector network analyzer

Synthetic Aperture Radar for Small Satellite

Small satellites are growing because they have shorter development cycles, lower cost, new technologies, and more frequent access to space. Sensors for Small satellites come with trade-offs to allow them fit within the mass, size, power and weight constraints imposed by the platform, these trade-offs between sensor system parameters can affect the mission requirements. Considering traditional SAR mission, each frequency band has different capability of penetration and special image characteristics, so the final SAR application will determine the appropriate bands needed. Small satellites come with constraints on the SAR sensor, so an analysis of SAR sensor system parameters (antenna length, antenna width and average transmitted power) at L, C and X band given a determined performance parameters is presented to analyze the effect of these frequency change on the system parameters and to determine the frequency band that is more suitable to fit within the small satellite SAR sensors constraints.

Compact Wideband Dual-Frequency Antenna Based on a Simplified Composite Right/Left-Handed Transmission Line with Hilbert Curve Loading

This paper addresses the issues of low bandwidth, gain, and efficiency of miniaturized microwave antennas by proposing a novel wideband dual-frequency coplanar waveguide antenna design based on a simplified composite right/left-handed (SCRLH) transmission line structure with Hilbert curve loading. The multifrequency characteristics of the SCRLH transmission line structure are evaluated theoretically, and the antenna parameters promoting bandwidth broadening under zeroth-order resonance (ZOR) and first-order resonance (FOR) mode operation are evaluated. The bandwidth broadening in the ZOR and FOR modes is accordingly revealed to be independent of the antenna length, and the structure therefore facilitates wideband operation under miniaturization. Finally, the dual-frequency ZOR and FOR mode antenna design with center frequencies of f0 = 1.865 GHz and f1 = 2.835 GHz is validated via simulation, and the performance of a compact prototype antenna is evaluated experimentally. The −10 dB return loss bandwidths at f0 and f1 are 187 MHz (from 1.773 GHz to 1.96 GHz) and 368 MHz (from 3.002 GHz to 3.37 GHz), and the corresponding relative bandwidths are 10.1% and 11.5%, respectively. The experimentally measured peak gains and radiation efficiencies at f0 are 1.54 dB and 81.3%, respectively, and those at f1 are 1.71 dB and 74.2%, respectively.

Evolution of male antennal size in moths (Lepidoptera): a comparative test of potential trade‐offs and correlated growth in Australian species

AbstractOne of the most conspicuous features of many moth species is their antennae, which can be strikingly elaborate. However, the factors that have influenced the evolution of these impressive receptor organs remain poorly known. Antennae are potentially costly structures, and previous research has indicated that investment in these structures may be traded‐off against investment in other organs, depending on the mating strategy in which individuals engage. Using a phylogenetic comparative analysis of data from dissected wild‐caught individuals from 44 Australian moth species, we examined potential trade‐offs and correlations between antennal size (measured as antenna length and antenna area) and the size of a range of other morphological features related to paternity (testis area), and vision (eye diameter). Antenna area did not show any evidence of a trade‐off with testis size (area) after controlling for body size and phylogeny. Further, relative antenna length was positively correlated with relative eye size, suggesting that investment in both sensory structures is linked. Analysis of the allometric scaling of antennal size and eye diameter found that larger moth species invested relatively more in the size of their male antennae (both area and length) than in the size of their eyes. These results indicate different patterns of investment in sensory structures in relation to body size, with larger moth species favouring the evolution of more elaborate antennae in males.

The study of the wideband planar sleeve antenna

In this paper, the wideband planar sleeve antenna with two sleeves on the upper side and two sleeves on the bottom side are analyzed numerically. In the previous study, the wideband planar sleeve antenna is used at frequency 3.5 GHz. The purpose of this research is addressed to analyze the wideband planar sleeve antenna in the range frequency of 400-4000 MHz by using WIPL-D EM Simulator by adjusting the antenna parameter. The antenna upper sleeve, lower sleeve, the length of the antenna and the gap between the lower and upper sleeves are adjusted. The result shows that the wideband planar sleeve antenna is achieved. When the length of the upper sleeve is increased, the antenna will work at lower frequency but the return loss slightly reduced, the same effect occurred by increasing the lower sleeve size, but it doesn’t affect at the lower frequency. When the antenna length is increased, the return loss of the antenna is reduced. Furthermore, the distance between the lower and upper sleeve affects the return loss characteristic. This is indicated that by adjusting the length of the antenna parameter, the antenna is applicable for many systems, such as television system and the ISM system.

Exposure of Macrobrachium rosenbergii (De Man, 1879) post-larvae to different nitrate concentrations: Effect on performance and welfare

The present study aimed to determine the effect of acute and chronic exposure to nitrate on the zootechnical performance and welfare of Macrobrachium rosenbergii post-larvae. In order to assess acute nitrate toxicity, M. rosenbergii post-larvae (n=280) were exposed to seven concentrations in quadruplicate (0, 10, 50, 100, 200, 400, and 800 mg L−1 N–NO3−) for 96 h. The results showed LC50 values for 24, 48, 72, and 96 h of approximately 352, 192, 114, and 87 mg L−1 nitrate, respectively. The safety level (SL) of nitrate was estimated at 8.62 mg L−1. Chronic toxicity was assessed based on the SL established during the acute test. The chronic experimental design comprised five treatments and three replicates, namely, control (no nitrate - 0 mg L−1), half the SL (4.5 mg L−1), the SL itself (9 mg L−1), twice the SL (18 mg L−1), and four times the SL (36 mg L−1), with the post-larvae (n=400) being exposed for 24 days. By the end of the experiment, survival, weight, length, final biomass, antenna length, and scaled mass index (SMI) were assessed. The chronic toxicity test showed a negative trend in survival and biomass with reductions from 89 to 28% and 0.72 to 0.23 g, respectively, as concentration increased from 0 to 36 mg L−1. A significantly negative effect was also observed for weight (0.036 to 0.019 g), total length (1.72 to 1.36 cm), and mean antenna length (2.32 to 1.72 cm) (F = 6.18; P = 0.00013). The SMI was also impacted by the increase in nitrate concentration. It can be concluded that concentrations above 4.5 N–NO3- (half the safety level) are not recommended for the production of M. rosenbergii post-larvae.