Antenna Length Research Articles

Whistler Waves in the Young Solar Wind: Statistics of Amplitude and Propagation Direction from Parker Solar Probe Encounters 1–11

In the interplanetary space solar wind plasma, whistler waves are observed in a wide range of heliocentric distances (from ∼20 solar radii (RS) to Jupiter’s orbit). They are known to interact with solar wind suprathermal electrons (strahl and halo) and to regulate the solar wind heat flux through scattering the strahl electrons. We present the results of applying the technique to determine the whistler wave propagation directions to the spectral data continuously collected by the FIELDS instruments on board Parker Solar Probe (PSP). The technique was validated based on the results obtained from burst mode magnetic and electric field waveform data collected during Encounter 1. We estimated the effective length of the PSP electric field antennas for a variety of solar wind conditions in the whistler wave frequency range and utilized these estimates for determining the whistler wave properties during PSP Encounters 1–11. Our findings show that (1) the enhancement of the whistler wave occurrence rate and wave amplitudes observed between 25 and 35 RS is predominantly due to the sunward-propagating whistler wave population associated with the switchback-related magnetic dips; (2) the antisunward or counterpropagating cases are observed at 30–40 RS; (3) between 40 and 50 RS, sunward and antisunward whistlers are observed with comparable occurrence rates; and (4) almost no sunward or counterpropagating whistlers were observed at heliocentric distances above 50 RS.

Morphological characteristics and density of Bracon (Habrobracon) concolorans Marshall,1900 (Hymenoptera: Braconidae), a native Turkish parasitoid of Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), on greenhouse-grown tomatoes in Antalya, Türkiye

Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) is one of the most significant pests of tomato. Chemical pesticides are prioritized in pest control, and this poses risks to both the environment and human health. Although commercial biological agents are occasionally?increasingly? used for control, understanding the density of existing parasitoids and predators of the pest is crucial for the effectiveness of integrated pest management. In this study, the parasitism rate of the native parasitoid Bracon (Habrobracon) concolorans Marshall, 1900 (Hymenoptera:Braconidae) collected from T. absoluta infesting tomato plants Antalya was investigated. Tomato leaf samples were collected weekly from a greenhouse in Elmalı/Antalya in October-November 2019, and cultured. The samples were monitored daily to record the number of pests and parasitoids that reached the adult stage. According to the results, 2004 T. absoluta and 478 B. (H.) concolorans adults were obtained from 221 infedted leaves. The number of parasitoids reaching the adult stage ranged from 1.7 adults to 2.6 adults per leaf. The study also included determinationss of the morphological characteristics of the Antalya population of the parasitoid. Accordingly, the average body length of the parasitoid was 2.13 mm in males and 2.37 mm in females. The average antenna length in males and females was 2.04 mm and 1.80 mm, respectively,and the number of antenna segments was 20-23 and 18-21, respectively.The average ovipositor length was 0.59 mm.

Optimizing inset-fed rectangular micro strip patch antenna by improved particle swarm optimization and simulated annealing

ABSTRACT The recent wireless communication systems require high gain, lightweight, low profile, and simple antenna structures to ensure high efficiency and reliability. The existing microstrip patch antenna (MPA) design approaches attain low gain and high return loss. To solve this issue, the geometric dimensions of the antenna should be optimized. The improved Particle Swarm Optimization (PSO) algorithm which is the combination of PSO and simulated annealing (SA) approach (PSO-SA) is employed in this paper to optimize the width and length of the inset-fed rectangular microstrip patch antennas for Ku-band and C-band applications. The inputs to the proposed algorithm such as substrate height, dielectric constant, and resonant frequency and outputs are optimized for width and height. The return loss and gain of the antenna are considered for the fitness function. To calculate the fitness value, the Feedforward Neural Network (FNN) is employed in the PSO-SA approach. The design and optimization of the proposed MPA are implemented in MATLAB software. The performance of the optimally designed antenna with the proposed approach is evaluated in terms of the radiation pattern, return loss, Voltage Standing Wave Ratio (VSWR), gain, computation time, directivity, and convergence speed.

Microwave analogy of Förster resonance energy transfer and effect of finite antenna length

The near-field interaction between quantum emitters, governed by Förster resonance energy transfer (FRET), plays a pivotal role in nanoscale energy transfer mechanisms. However, FRET measurements in the optical regime are challenging as they require nanoscale control of the position and orientation of the emitters. To overcome these challenges, microwave measurements were proposed for enhanced spatial resolution and precise orientation control. However, unlike in optical systems for which the dipole can be taken to be infinitesimal in size, the finite size of microwave antennas can affect energy transfer measurements, especially at short distances. This highlights the necessity to consider the finite antenna length to obtain accurate results. In this study, we advance the understanding of dipole–dipole energy transfer in the microwave regime by developing an analytical model that explicitly considers finite antennas. Unlike previous works, our model calculates the mutual impedance of finite-length thin-wire dipole antennas without assuming a uniform current distribution. We validate our analytical model through experiments investigating energy transfer between antennas placed adjacent to a perfect electric conductor mirror. This allows us to provide clear guidelines for designing microwave experiments, distinguishing conditions where finite-size effects can be neglected and where they must be taken into account. Our study not only contributes to the fundamental physics of energy transfer but also opens avenues for microwave antenna impedance-based measurements to complement optical FRET experiments and quantitatively explore dipole–dipole energy transfer in a wider range of conditions.

EKSPLORASI JENIS-JENIS LEBAH MADU TAK BERSENGAT DI KEPULAUAN ARU

Exelation aims to find what types of stingless honey bees are there in the Aru Islands. The research was carried out on the Aru Islands, Wamar Island (Wangel and Durdiela Village), Kobror Island (Warbola and Benana Village), and Koba Island (Mutrai and Koba Village) from March to July 2022. The method used in preciation in Vata is a descriptive method, namely identifying stingless honey bees through observation, morphological characteristics and measurements, morphometrics and describing the location of the eccomium. Research shows that stingless honey bee stings were found. In Kalman Aru there were 36 active colonies at a height of 1-241 cm, with nesting sites found namely cave cavities, stone cavities and Ulouran rates. The average morphometric character of Tetragonula capens worker stratum bees found was long. body 374-4 25mm, head width 177-1 81mm. head space 1 47-1 55mm, wing length 3.81-4-35mm, antenna length 170-173mm, while Tetragonula cobalteata which was found, body length 278-324mm, head width 1 18-132 mm, head length 109-123 mm wing length and tegula 316-3.22 mm, and antenna length 2 18-2.22 mm.

Comb age significantly influences the emergency queen rearing, morphometric and reproductive characteristics of the queens

A study on the impact of comb age on the number of emergency queen cells and ripped queen cells was conducted. Also, we compared morphometric and reproductive characteristics of queens reared in combs aged 1, 2, 3, and 4 years. The highest number of emergency queen cells was constructed in combs aged 1 year on the 2nd day after dequeening. No more queen cells were constructed after the 5th day of dequeening. The highest numbers of successful queen cells and emerged queens were obtained from the new combs. The amount of royal jelly (RJ)/queen cell, the weight of the newly emerged queen, and the queen cell size significantly decreased with increasing the age of the comb. Compared with the newly emerged queens from combs aged 1 year, the queens from combs aged 3 and 4 years exhibited significantly lower values for antenna length, mandibular gland area, forewing area, number of hamuli, area of the 3rd and 4th abdominal tergites, abdomen length, number of ovarioles/ovary, ovariole length and diameter, and spermathecal size. Significant positive correlations between the queen cell size and RJ yield/queen cell, queen body weight, and all queen characteristics except for the hindwing area were found. It can be concluded that the number of reared queens and their morphometrics and reproductive characteristics were significantly dependent on the age of the combs. The queen’s body size can be used as an indicator of the queen’s quality.

Numerical study of the induction of intratumoral apoptosis under microwave ablation by changing slot length of microwave coaxial antenna.

Recent advances in technology have led to an increase in the detection of previously undetected deep-located tumor tissue. As a result, the medical field is using a variety of methods to treat deep-located tumors, and minimally invasive treatment techniques are being explored. In this study, therapeutic effect of microwave ablation (MWA) on tumor generated inside liver tissue was analyzed through numerical analysis. The distribution of electromagnetic fields in biological tissues emitted by microwave coaxial antenna (MCA) was calculated through the wave equation, and the thermal behavior of the tissue was analyzed through the Pennes bioheat equation. Among various treatment conditions constituting MWA, tumor radius and the slot length inside the MCA were changed, and the resulting treatment effect was quantitatively confirmed through three apoptotic variables. As a result, each tumor radius has optimal power condition for MWA, 2.6W, 2.4W, and 3.0W respectively. This study confirmed optimal therapeutic conditions for MWA. Three apoptotic variables were used to quantitatively identify apoptotic temperature maintenance inside tumor tissue and thermal damage to surrounding normal tissue. The findings of this study are expected to serve as a standard for treatment based on actual MWA treatment.

Compact Series-fed Circularly-polarized Patch Array basedon Microstrip Line

A compact single-layer circularly polarized (CP) antenna array is proposed in this paper for 5G/6G applications. The conventional microstrip line is modified as a feeding network by periodically and alternatively loading field blocking stubs, producing a linearly polarized in-phase radiative field aperture. By adding CP corner-truncated patches beside these in-phase fields, a linear high-gain CP antenna array excited by a single feed is obtained. The feasibility of the proposed design is demonstrated through the fabrication and measurement of a 16-element linear array. The results indicate that the 3 dB axial ratio bandwidth is 3.5% (19.60∼20.30 GHz), the -10 dB impedance bandwidth totally covers the 3 dB axial ratio bandwidth, and the peak realized gain is 14.9 dBi under an antenna length of 5.69λ0. This proposed strategy provides a very compact antenna structure to achieve high-gain CP radiation without the requirement of impedance transformers, phase shifters, and open-stop-band suppressing measures. Moreover, the antenna has a per-unit-length CP gain of 5.5/λ0, which is superior to many single-layer high-gain CPantennas.

Radial Distribution of Electron Quasi-thermal Noise in the Outer Heliosphere

Voyager 1 and 2 are only the two spacecraft that have arrived and passed through the heliospheric boundaries. Based on the plasma data from the Voyager 2 spacecraft, the electron quasi-thermal noise (QTN) is investigated by using of the electron population model consisting of a core with Maxwellian distribution and a halo with kappa distribution. The power spectra of the electron QTN is calculated at different heliocentric distances from 1 to 110 au. The parametric dependence of the QTN power spectra and the effective Debye length on the model parameters, such as the density ratio and temperature ratio of the halo to the core, kappa index and the antenna length, are discussed further. The results show that the electron QTN spectrum consists of a plateau in the low frequency band f < f pt , a prominent peak at the plasma frequency f pt , and a rapid decreasing part in the high frequency band f > f pt . The QTN plateau level basically falls down outwards until the termination shock crossing at about 84 au, after which the plateau rebounds a little near the heliopause. Although the model parameters can be very variable, the QTN plateau level does not present more than the double change in a fairly wide range of the model parameters. The presented results can be useful for future deep-space explorations in the heliosphere and can provide valuable references for the design of onboard detectors.

The coax monopole antenna: A flexible end-fed antenna for ultrahigh field transmit/receive arrays.

The coax monopole antenna is presented for body imaging at 7 T. The antenna is fed at one end, eliminating the possibility of cable-coil coupling and simplifying cable routing. Additionally, its flexibility improves loading to the subject. Like the coax dipole antenna, an interruption in the shield of the coaxial cable allows the current to extend to the outside of the shield, generating a B1 + field. Matching is achieved using a single inductor at the distal side, and a cable trap enforces the desired antenna length. Finite difference time domain simulations are employed to optimize the design parameters. Phantom measurements are conducted to determine the antenna's B1 + efficiency and to find the S-parameters in straight and bent positions. Eight-channel simulations and measurements are performed for prostate imaging. The optimal configuration is a length of 360 mm with a gap position of 40 mm. Simulation data show higher B1 + levels for the coax monopole (20% in the prostate), albeit with a 5% lower specific absorbance rate efficiency, compared to the fractionated dipole antenna. The S11 of the coax monopole exhibits remarkable robustness to loading changes. In vivo prostate imaging demonstrates B1 + levels of 10-14 μT with an input power of 8 × 800 W, which is comparable to the fractionated dipole antenna. High-quality images and acceptable coupling levels were achieved. The coax monopole is a novel, flexible antenna for body imaging at 7 T. Its simple design incorporates a single inductor at the distal side to achieve matching, and one-sided feeding greatly simplifies cable routing.

Different Protein Hydrolysates Can Be Used in the Penaeus vannamei (Boone, 1934) Diet as a Partial Replacement for Fish Meal during the Grow-Out Phase

This study evaluated the inclusion of protein hydrolysates and a commercial product as a partial replacement for fish meals in the diet of Pacific white shrimp (Penaeus vannamei) during the grow-out phase. A recirculation system with 24 experimental units and a biological filter was used. The experimental design was completely randomized with six treatments: control; chicken protein hydrolysate (CPH); enzymatic hydrolysate of chicken feathers; Aquabite®; CPH + maltodextrin; CPH + yeast; and four replicates. After 50 days, the zootechnical performance and animal welfare parameters, centesimal carcass composition, digestive enzyme activity, and hemocyte count were evaluated. The treatments did not affect the zootechnical performance and total hemocyte count of the animals (p &gt; 0.05). The evaluation of the antenna length indicated that all animals were in good health. The antenna length in treatment T5 was significantly greater (p &gt; 0.05) than that in T4 and similar to that in treatments T3 and T6, demonstrating a positive influence of dietary protein hydrolysates. Concerning animal welfare, dietary protein hydrolysates influenced the length of the antenna (p &lt; 0.05). The antenna length associated with different treatments indicated that the animals were in good welfare conditions in the production environment. With respect to body chemical composition, dry matter, ether extract, and ash were affected by the treatments (p &lt; 0.05). Regarding the analysis of digestive enzymes, the treatments influenced the activities of amylase and trypsin (p &lt; 0.05). The performance of the animals was satisfactory under all treatments, including enzymatic activity, demonstrating the possibility of using hydrolysates.

Optical nanoimaging of laser-switched phase-change plasmonic infrared antennas.

We investigate the plasmonic properties of laser-printed chalcogenide phase-change material In3SeTb2 (IST) antennas through near-field nanoimaging. Antennas of varying lengths were fabricated by laser switching an amorphous IST film into its crystalline metallic state. Near-field imaging elucidates the pronounced field confinement and enhancement at the antenna extremities along with the emergence of different ordered plasmonic modes with increasing length. Compared to gold antennas, the PCM antennas exhibit slightly lower but still substantial near-field enhancement with greater compactness. The interplay between antenna length, illumination angle, and excitation frequency enables versatile control over the resonant near-field distribution. Our work provides deeper understanding and tunable functionalities of laser-printed PCM nanoantennas for potential applications in compact, dynamically reconfigurable nanophotonic devices.

Effect of Elevated Temperature on the Bionomics of &lt;i&gt;Aenasius arizonensis&lt;/i&gt; Girault

An experiment was conducted to know the effect of thermal stress on the biological attributes of the parasitoid Aenasius arizonensis Girault of the cotton mealybug Phenacoccus solenopsis Tinsley. The results revealed that temperature showed a significant effect on the biological fitness traits of the A. arizonensis; when exposed to 32°C, parasitisation, fecundity, female sex ratio and adult longevity. At 32°C these viz., parasitisation (77%), sex ratio (63.46) and days taken from oviposition to mummy formation (6.4) were found to be the highest. Other fitness traits like fecundity (142.8) and developmental duration (11.2 - males, 12.6 - females) were found to be the highest at 27°C. These parameters gradually decreased with increasing temperature, indicating a negative relationship. Morphometrics of adults revealed that mean length and breadth of mummies, total length and breadth of adult male and females, total width of head, total length of antenna and total hind tibial length were maximum at 27°C as compared to those observed with high temperature treatments. Thus high temperature was observed to have an adverse effect on the growth and development of the parasitoid.

3-D printed high-gain elliptic flat Luneburg lens

The antennas on remote sensing satellites play a crucial role in receiving and transmitting wireless signals, affecting data acquisition quality. Among them, Luneburg lens antennas have been successfully applied in satellite tracking due to their high-gain property. However, reducing the flat Luneburg lens(FLL) profile while maintaining performance and addressing manufacturing challenges remains a limitation. This paper first utilizes transformation optics theory to derive the permittivity distribution of the FLL. Moreover, an innovative approach is introduced by multiplying the distribution with a coefficient “g” to achieve the desired lower permittivity required for fabrication. Then, a layered implementation is used to design a circular FLL and improve its performance by compressing its horizontal profile. Therefore, a unique elliptic FLL is proposed by making a trade-off between the gain, beamwidth, and focal length of the lens antenna. The antenna achieves a 22.9 dB maximum gain with beamwidths of 9.5°(E-plane) and 7.4°(H-plane). The elliptic FLL was fabricated using 3D printing technology, and the measured results showed a small deviation from the simulated results within an acceptable range of error. The elliptic FLL possesses design flexibility and holds immense potential in applications such as remote sensing satellite communication.

Considerations for radio-transmitter specifications on songbirds: color and antenna length matter too

Considerations for radio-transmitter specifications on songbirds: color and antenna length matter too

Forest age is a primary trait filter for saproxylic beetles in the southeastern United States

Many forests throughout the world consist of regenerating mature stands. Although these forests differ in many respects from old-growth (with a history of minimal human disturbance), they typically develop similar structural attributes over time. As a result, older mature forests may be of particular conservation value if they contain resources and microhabitats benefitting saproxylic (deadwood dependent) species. Species’ response to forest age may be driven by traits that relate to ecological functions or habitat preferences, such that species with less compatible traits for a local forest environment are “filtered” out. Thus, forest age may influence species’ distributions and the trait composition of assembled communities.The Piedmont region of the southeastern United States has experienced widespread forest regrowth over the past century due to agricultural abandonment. Today’s landscapes are largely characterized by mature forests that are becoming increasingly fragmented by suburbanization. Here, we assessed the filtering effects of forest age, landscape forest cover (LFC), and deadwood volume on saproxylic beetles in northeastern Georgia. Using historic aerial imagery to distinguish forest age (young = regrown after 1938; old = mature in 1938), we sampled beetles in mature forests of both age classes occurring along an LFC gradient. We measured five traits with hypothesized functional roles (body length, body width, body roundness, antenna length, eye length) for the 472 species captured. Using a joint species distribution model (JSDM), we tested trait-niche relationships (i.e., how traits influence species’ responses) and estimated community trait composition (mean and dispersion of trait values) along gradients of environmental filters.We found that forest age is a filter for several traits (six supported relationships with > 95 % posterior probability), but LFC and deadwood volume were less strongly related to fewer traits. Most notably, large species (typically having lower population sizes and requiring stable larval habitat) were filtered from young mature forests and low LFC. Thus, old mature forests with high LFC showed higher mean and dispersion of beetle body length. Sensory traits also showed responses, likely reflecting adult life under bark (eye length) or ability to detect resources or mates (antenna length). Body width and roundness showed inconsistent responses with regard to indicated functional roles. Our results show that forest age is a strong filter on saproxylic beetle communities in the southeastern United States. Old mature forests, despite their scarcity in the region, are important for species requiring habitat stability and for maintaining communities with diverse trait composition.

Cosecant-squared pattern synthesis of leaky-wave antenna using ridge waveguide

Antennas with a cosecant-squared pattern play a significant role in air-surveillance radar systems. In this article, a cosecant-squared pattern leaky-wave antenna (LWA) is synthesized using a ridge waveguide. The LWA consists of periodic shunt slots located at the broad wall of a ridge waveguide. To obtain the desired cosecant-squared pattern, the attenuation and the phase constant must be controlled properly along the antenna length. To this end, the slots offset and the ridge profile are properly tapered along the antenna. This adjustment is performed through an optimization algorithm such as a genetic algorithm (GA) optimization. Through the proposed antenna configuration, a cosecant-squared pattern LWA with a wide range of 10° to 40° together with low ripples (≤2 dB) in the shaped region and a low level of sidelobes (≤−18 dB) is synthesized, fabricated and measured. Apart from the good agreement between the simulation and the measurement results, such a design indicates a size reduction (about 47%) compared with the previous published work.

Design and characterization of mesoscopic dielectric cuboid antenna for operation in WR-3.4 waveguide bandwidth (220–330 GHz)

We designed a mesoscopic dielectric cuboid antenna connected to a flangeless WR-3.4 open-ended waveguide, and the antenna characteristics at 300 GHz were examined through simulations and experiments. Simulations confirmed that the flangeless design eliminated the flange-induced ripples in the radiation pattern, whose shape varied with frequency, and that the antenna operated in the full bandwidth of the WR-3.4 waveguide (220–330 GHz). Prototypes were then fabricated based on the simulation findings. A prototype with an antenna aperture area of 1.5 mm times 1.5 mm and an antenna length of 2.35 mm exhibited an antenna gain of 17.2 dBi at 300 GHz and a voltage standing wave ratio of less than 1.5 throughout the WR-3.4 waveguide bandwidth. The level of the side lobes at about pm 30 degrees in the E-plane pattern was approximately -10 dB that of the main lobe. Therefore, the proposed antenna, connected to a flangeless waveguide, is a promising antenna for use in future short-range high-speed terahertz wireless applications such as kiosk downloads and board-to-board communication.

Multiband deformed off-set octagonal patch antenna with improved impedance matching

A novel method is proposed to achieve a single layer miniaturized multiband side-fed microstrip patch antenna for mobile communication applications. Unlike the conventional microstrip antenna with a microstrip line side feed, the integration of a rectangular strip, triangular radiation element, and off-set octagonal radiation patch contributes to the impedance matching, radiation of the multiband signals, and reduction of the length of the regular side-fed antenna. The analysis reveals that a TM01, TM21, and TM22 modes at 1.85, 2.3, and 3.38 GHz, respectively, are excited to realize the multiband radiation. The measurements show that the proposed antenna can work in the 1850/2310/3380 MHz multiple frequency bands simultaneously and can be integrated with planar circuits using a simple structure.

Some Morphological Variation of Dwarf Honeybee, Apis florea Fab. in Northern and Southern Iraq

Alebty, M.A., I.M. Farag and K.O. Ali. 2023. Some Morphological Variation of Dwarf Honeybee, Apis florea Fab. in Northern and Southern Iraq. Arab Journal of Plant Protection, 41(3): 332-338. https://doi.org/10.22268/AJPP-41.3.332338 The dwarf honeybee, Apis florea Fab. is a successful ecologically adaptive and important factor in pollinating crops. It has recently spread widely in Iraq. To investigate the variability of this bee species, samples of worker bees from different regions of Iraq (North, Kurdistan Region and Southern, Basra province) were collected during the period from March to December 2021. Ten body morphological traits of worker bees and nine wing traits were selected for this study. The statistical analysis of the results obtained showed a clear discrepancy in the measurement of the studied characters, as sizes were less in the southern bees compared to northern bees for head length, antenna length, femur length, tibia length, 3 rd sternite length, 4 th tergite length, front wing width and length, angle A4, angle B4, angle D7, angle G18 and angle K19. This is the first record of dwarf honeybee in Kurdistan province in Iraq. Keywords: Apis florea, honeybees, morphological characters, adaptation, hot areas, cold areas, Iraq