Characteristics Of Antennae Research Articles

Neuromorphic antennal sensory system

Insect antennae facilitate the nuanced detection of vibrations and deflections, and the non-contact perception of magnetic or chemical stimuli, capabilities not found in mammalian skin. Here, we report a neuromorphic antennal sensory system that emulates the structural, functional, and neuronal characteristics of ant antennae. Our system comprises electronic antennae sensor with three-dimensional flexible structures that detects tactile and magnetic stimuli. The integration of artificial synaptic devices adsorbed with solution-processable MoS2 nanoflakes enables synaptic processing of sensory information. By emulating the architecture of receptor-neuron pathway, our system realizes hardware-level, spatiotemporal perception of tactile contact, surface pattern, and magnetic field (detection limits: 1.3 mN, 50 μm, 9.4 mT). Vibrotactile-perception tasks involving profile and texture classifications were accomplished with high accuracy (> 90%), surpassing human performance in “blind” tactile explorations. Magneto-perception tasks including magnetic navigation and touchless interaction were successfully completed. Our work represents a milestone for neuromorphic sensory systems and biomimetic perceptual intelligence.

Microscopic morphology and distribution of the antennal sensilla in the double-spined bark beetle, Ips duplicatus (Coleoptera: Curculionidae).

The double-spined spruce bark beetle, Ips duplicatus, has become an infamous secondary pest of Norway spruce, causing extensive ecological and economic destruction in many Central European countries. Antennae are the primary olfactory organs that play a fundamental role in insect-host chemical communication; therefore, understanding morphology is crucial before conducting electrophysiological investigations. Here, we present our analysis of sensilla types on the antennal surface of I. duplicatus for the first time, using high-resolution-scanning electron microscopy. We studied the external morphological characteristics of antennae and the types, numbers, and distribution of the antennal sensilla in males and females. Our results revealed the presence of five different types of morphologically distinct sensilla: sensilla chaetica, sensilla basiconica, sensilla trichodea, sensilla coeloconica, and Böhm's sensilla. We observed two subtypes of sensilla chaetica (SChI and SChII), four subtypes of sensilla basiconica (SBI, SBII, SBIII, and SBIV), three subtypes of sensilla trichodea (STrII, STrIII, and STrIV) and two subtypes of sensilla coeloconica (SCoI and SCoII), respectively in I. duplicatus males and females. Minor differences in length and numbers between the sexes for some sensilla types were found. Distribution maps for different sensillar types were constructed, and specific areas for the respective sensilla were found. Possible functions of observed sensilla types are discussed. The present study provides a basis for future electrophysiological studies to understand how I. duplicatus detects ecologically important olfactory cues. RESEARCH HIGHLIGHTS: • The first report of morphology and distribution pattern of the antennal sensilla in Ips duplicatus is discussed. • A total of 6 main types and 11 antennal sensilla subtypes were observed in male and female Ips duplicatus. • Minor sex-specific differences were seen in the length and numbers in several sensilla types.

Comparison of Morphological Characteristics of Antennae and Antennal Sensilla among Four Species of Bumblebees (Hymenoptera: Apidae).

Bumblebees, as pollinators, play an important role in maintaining natural and agricultural ecosystems. Antennae with sensilla of bumblebees as social insects have essential effects in foraging, nest searching, courting, and mating, and are different in species and sexes. Previous studies on the morphology of antennae and sensilla in bumblebees have been limited to a few species and a single caste. To better understand how bumblebees detect and receive the chemical signal from nectariferous plants and foraging behavior, the morphology of antennae with sensilla, including the antennal length, and type, distribution, and number of antennal sensilla in four species, Bombus atripes, Bombus breviceps, Bombus flavescens, and Bombus terrestris was compared by scanning electron microscopy (SEM) herein. The total antennal length of queens are the longest and workers are the shortest in three castes, and in four species the longest of the total antennal length among three castes all are in B. flavescens, which is significantly longer than other species (p < 0.05) and the length of the scape in queens and workers are both longer than males, significantly different in queens (p < 0.05), and not significantly different in workers (p > 0.05), and the length of flagellums in females are not always shorter than males, of which the length of flagellms in queens of B. flavescens are significantly longer than males (p < 0.05), and the length of pedicel and all flagellomeres varies among species and castes. A total of 13 major types of sensilla in total were observed, including trichodea sensilla (TS A-E), placodea sensilla (PS A-B), basiconica sensilla (BaS), coeloconica sensilla (COS A-B), chaetic sensilla (CS A-B), and Böhm sensilla (BS), of which chaetic sensilla B (CS B), only observed in females of B. atripes, was firstly reported in Apidae. Moreover, the number of all sensilla was the most in males, the least was in workers, the number of sensilla varies within castes and species. Furthermore, the morphological characteristics of antennae and the potential functions of sensilla are discussed.

Optimization of terahertz detectors based on graphene field effect transistors by high impedance antennae

This contribution presents the results of investigations performed on monolayer graphene field effect transistor- based (GFET-based) terahertz detectors. We have implemented three different types of planar antennae: a bowtie, a bow-tie with transmission lines and a slot-disc, allowing us to realize different conditions for high-frequency impedance matching. We present a semi-empirical model which uses physical parameters derived from electrical characterization results of devices and electrodynamic characteristics of antennae, allowing us to predict THz responsivity. Model predictions have been compared with the responsivity measurements performed at room temperature in a frequency range from 50 to 1250 GHz. Good agreement between the model predictions and experimental results implies the eligibility of a distributed resistive mixing approximation for GFET. In addition, the device stability, the temperature dependence and the origin of noise in the transistor channel have been investigated. Finally, to the best of our knowledge, we demonstrate the record performance values for room temperature graphene-based terahertz detectors: 80V/W optical responsivity without the normalization to the antenna effective area and a noise equivalent power of 111 pW/√Hz at 336 GHz.

Investigating process technologies for production of carbon composite material antennas for maritime radio communication systems

The paper is dedicated to studying manufacturing prospects of antenna devices from carbon composite materials and suggests technical solutions aimed at water transportation radio communication needs. Principal physical parameters of the carbon composite material used in manufacture and subsequent studies of antenna specimens were compared to those of metals. Peculiarities of manufacturing carbon composite antenna devices have been considered. Antenna specimens were experimentally studied for their electromagnetic characteristics, while their digital copies were studied in simulation. Similarities are pointed out between the main characteristics of composite antennae and their metal analogs. Efficiency of proposed technical solutions and antenna building technologies are demonstrated for application of carbon composite antennas in marine radio communication.

Gynandromorphic Specimens of Culex erythrothorax, Culex pipiens Complex, Culex tarsalis, and Culiseta incidens Collected in Northern San Joaquin Valley, California.

Gynandromorphic insects bear both male and female characteristics. In mosquitoes, gynandromorphy has been documented in multiple species and it can include many different combinations of sex-specific traits such as plumose or filiform antennae, short or elongated palpi, and male or female terminalia. Here we report 4 gynandromorphic specimens of Culex erythrothorax, Cx. pipiens complex, Cx. tarsalis, and Culiseta incidens collected in the Northern San Joaquin Valley of California. Each of the specimens exhibited heads with female characteristics of short palpi and filiform antennae while displaying fully developed external male terminalia including basistyles and dististyles. The potential implication of gynandromorphism in genetic control of mosquito vectors is discussed.

Effects of Macondo Oil on Phytoplankton from Grand Isle, Louisiana

Bioassays were performed on phytoplankton communities from the coastal waters at Grand Isle, Louisiana from February through August 2013 to determine the impact of the water-accommodated fraction of unweathered Macondo well oil on the growth rates and taxonomic composition of the phytoplankton. Pigment analysis indicated that diatoms dominated the natural phytoplankton communities, and with one exception, diatoms were the only class of phytoplankton that grew in control cultures or in artificial seawater amended with the water-accommodated fractions of Macondo well oil at a series of concentrations from 0.1 to 19.2 mg L–1. The growth rates of diatoms were enhanced by roughly 10% at oil concentrations ≤ 0.6 mg L–1 but were reduced by up to 30% at concentrations ≥ 1.0 mg L–1. Ratios of fucoxanthin to chlorophyll a were positively correlated with oil concentrations, an indication that there was some adjustment of the characteristics of the light-harvesting antennae of the diatoms in response to the stress of the oil.

Antennal morphology in the family Dolichopodidae (Diptera)

Nine hundred eighty species belonging to 182 genera of 15 subfamilies of the family Dolichopodidae were investigated to study antennal morphology. Length measurements of scape, pedicel, postpedicel and arista and height measurements of postpedicel bases were performed, and 4 ratios were selected. Use of morphometric characteristics of Dolichopodidae antennae allows meaningful distinctions between subfamilies to be made. Using these criteria, a cladistic tree of Dolichopodidae subfamilies was built.

Radiation Theory of the Plasma Antenna

Several basal theoretical problems for the radiation of plasma antenna are investigated. The system equations are obtained according to the rule of the disturbing current, which is excited by surface waves on the interface between a plasma column and a dielectric tube, and the radiation theory of dielectric antennae. The analysis indicates that there are two kinds of mechanisms to explain the radiation of plasma antennae. The first one is the radiation of the disturbing current, which is similar to the radiation of a metal antenna. In the second case, because the electromagnetic wave partly cannot satisfy the total reflection condition in some specific frequency bands, transmission can be excited in a plasma antenna, which is similar to the radiation of a dielectric antenna. The radiation derived from these two kinds of mechanisms can be superposed in certain frequency bands. In this paper, a radiation directivity function is obtained. The radiation characteristics of plasma antennae are compared with those of metal antennae. The radiation properties of plasma antennae are presented based on numerical calculation. The present results provide an important theory for further investigation in the performance of controlling plasma antennae and plasma antenna arrays.

Left-Handed Effect of Composite Rectangular SRRs and Its Application in Patch Antennae

We concentrate on describing the important influence and physical law of the split resonant ring (SRR) based left-handed materials on patch antennae. The finite-difference time-domain method, together with the finite element method is used to study the characteristics of patch antennae based on composite rectangular SRRs. A novel composite rectangular SRR system is formed by assembling the conventional patch antennae and SRRs, it is found that electromagnetic wave resonance occurs near f = 3.15 GHz, the equivalent permittivity and permeability are both negative, and the electromagnetic wave's tunnel effect and evanescent waves' enhancing effect are formed, which can improve the localization extent of electromagnetic wave's energy apparently. Such effects can improve the antenna's radiation gain and its matching condition. The phenomenon indicates that such composite rectangular patch antennae are promising in wireless communications such as mobile phones, satellite communication and aviation.

Experimental Investigations of Planar Dielectric Disk Antennae

The results of experimental investigations of planar dielectric disk antennae with different dielectric substrates and radiating elements are represented. Geometric and electric parameters of antenna prototypes have been chosen in accordance with the theoretical calculations [1] to provide the conditions of the ТМ01 mode excitation in the electromagnetic structure under study. It has been determined that the use of substrates with different values of the permittivity gives rise to the change in the antenna patterns and the field intensity in their lobes. Moreover, the use of dielectric disks with high permittivity (ed =90) provides an increase in the power radiated into the free space as well as a frequency band enhancement. Recently dielectric disk antennae have been used in increasing frequency as an alternative analogue of well-known planar disk metallic antennae. In accordance with the theoretical prerequisites [1] the use of a dielectric radiating element instead of metallic one must lead to an increase in the level of the power radiated into the free space as well as a frequency band enhancement of the antennae of this type. In this case, the using of disks and substrates, as elements of the antenna, with different values of the dielectric permittivity can have an influence on radiation characteristics of this type antennae. The purpose of this paper is the investigation of planar dielectric antennae and the determination of influence of permittivities of substrates and radiating elements on their characteristics. EXPERIMENT The results of experimental investigations of planar disk antennae are represented in the paper (Fig. 1). They consist of a dielectric substrate with the radius rs and a * Originally published in Radiophysics and Electronics, Vol. 10, No 1, 2005, pp. 98–101. ISSN 0040-2508 © 2005 Begell House, Inc. 727 A.S. ANDRENKO, I. V. IVANCHENKO, N. A. POPENKO, AND M. M. KHRUSLOV dielectric disk with the radius rd placed on a metal shield. To minimize the influence of the edge effects on the antenna pattern, we have taken the diameter of the substrate which is 3.5 times larger then the diameter of the disk. In the operating frequency band 8-10 GHz, the ratio of the dielectric permittivities ed and es of the disk and the substrate correspondingly as well as the diameter of the disk and the thickness hs of the substrate have been determined from the conditions of the ТМ01 resonant mode excitation in the structure [1]. As an antenna exciter we have used a vertical electric dipole in the form of a piece of the coaxial cable central core. The length of this piece is determined by the thickness of the substrate (Fig. 1). FIGURE 1. The configuration of the structure under the study: 1 is a dielectric disk; 2 is a dielectric substrate; 3 is a perfectly conducting shield; 4 is a coaxial cable We have measured the standing wave ratio, the near field distribution, and the antenna pattern with the following configuration (Table 1). Table 1 No Dielectric disks Substrates 1 rd = 22 mm, hd = 0.25 mm, ed = 7 rs = 220 mm, hs = 4 mm, es = 2.5 2 rd = 22 mm, hd = 0.25 mm, ed = 7 rs = 80 mm, hs = 4 mm, es = 2.05 3 rd = 25 mm, hd = 0.5 mm, ed = 90 rs = 220 mm, hs = 4 mm, es = 2.5 4 rd = 25 mm, hd = 0.5 mm, ed = 90 rs = 80 mm, hs = 4 mm, es = 2.05 1

Graphite as a structural material for the in-vessel components for plasma diagnostics in the millimeter and sub-millimeter ranges

Abstract The possibility to use the carbon-graphite materials (CGM) instead of metals for fabrication of the in-vessel components for plasma diagnostics in the mm and sub-mm ranges on large-scale fusion devices was investigated. The reflectivity of different kinds of CGMs (more than 20) was measured in the wavelength range of 10 μm-30 mm and was found to be only little below the values for metal analogues. The effects of surface roughness, pulsed plasma impact, heating and neutron irradiation on the reflectivity of CGM-made reflectors were analyzed. The role of graphite protection of the first wall in the energy balance in a fusion reactor was evaluated using the reflectivity data obtained. The working characteristics of antennae, waveguides and resonator fabricated of CGMs are presented as measured before and after pulsed plasma impact and/or heating up to 1000C. The CGM-made diagnostic components demonstrated much stronger resistance to pulsed power plasma impact than metal-made ones and at the same time reasonable working characteristics. Therefore they can successfully replace the metallic components in cases when similar (i.e., CGM) materials are used for the first wall protection.

On the possibility of using carbon-graphite materials for the inner elements of millimetre and sub-millimetre diagnostics of a fusion plasma

The paper presents data on radiotechnical characteristics of antennae and reflectors for mm and sub-mm wavelength ranges, made of carbon-graphite materials (CGM). It is shown that the reflectivity value of plane reflectors made of different kinds of CGM depends mostly on the surface roughness being close to that of metallic reflectors, and does not change significantly under neutron irradiation. Characteristics of CGM-made antennae are not much different from those for antennae made of metal. Pyramidal antennae made of CGM maintains its properties under imitated plasma disruption much better than a similar metallic one would.

The heat is on — but how? A comparison of TUMT devices

To compare the heat characteristics of the microwave antennae, the absorbed energy in the target volume and the cooling capacity of the catheters of three common devices for transurethral microwave thermotherapy (TUMT), i.e. the Prostcare, Prostatron and ProstaLund. The microwave emission from the respective catheters or antennae was measured in a tissue-equivalent 'phantom' prostate. From these measurements the distribution of absorbed energy from the respective catheters and antennae was calculated from the characteristics of the phantom, the absorbed energy and the temperature difference before and after heating. The cooling capacity of the different catheters were measured by submerging each catheter in a thermally isolated water bath at a known temperature and determining the cooling of the water bath caused by the catheter. The design of the microwave antenna influenced the heating profile significantly. The energy absorbed by the prostate model varied among the devices, but was between 13 and 21% of the stated applied energy. The cooling capacity also varied, being least in the Prostcare and greatest in the ProstaLund catheters. Users of TUMT should be aware of possible back-heating along the catheter, as this limits the microwave power that can be used safely. Furthermore, the 'treatment energy', which is commonly used as an indicator to describe the intensity of TUMT treatments, is ambiguous and not stringent, in that the microwave energy absorbed in the prostate is only a small fraction of this value.

A Survey of the Performance Characteristics of Television Receivers and Antennae for the UHF-TV Project'

A Survey of the Performance Characteristics of Television Receivers and Antennae for the UHF-TV Project'

An automatic contour plotter for the investigation of radiation patterns from directive antennae

An instrument is described which permits the rapid and accurate plotting of the complete radiation characteristics of directive antennae. The information is presented in the form of a contour map. This gives far more information than can be obtained from a simple polar diagram. The instrument itself is described in Section 2, and an example of the type of record produced is given. Section 3 describes the use of the device in solving a particular production problem and Section 4 gives a method of balance line plotting which was developed.

An automatic contour plotter for the investigation of radiation patterns of directive antennae

An instrument is described which permits the rapid and accurate plotting of the complete radiation characteristics of directive antennae. The information is presented in the form of a contour map. This gives far more information than can be obtained from a simple polar diagram.The instrument itself is described in Section 2, and an example of the type of record produced is given. Section 3 describes the use of the device in solving a particular production problem and Section 4 gives a method of “balance line” plotting which was developed.