Antenna Length Research Articles

Design of Compact D-shaped Frequency Reconfigurable Slot Antenna for Ku/K Band Applications

In this paper, a new compact design of frequency reconfigurable slot antenna is presented. The proposed radiating patch consists of two symmetrical D shape slots and incorporates four PIN diodes with two stubs which cover a small dimension area of 8.6 × 6.0 × 1.6 mm3. The ground plane is modified by etching two parallel rectangular slots to enhance the bandwidth and design parameter of the antenna. RF pin diodes are used as a switching mode in the slotted D section of the patch which affects the electrical length of the slot antenna, therefore switchable frequency response is obtained. The antenna produces four dual-band states and twelve triple-band states among the sixteen states of diode configuration. The designed antenna resonates at six different resonating frequencies such as 17.4 GHz, 17.5 GHz, 18.9 GHz, 19.0 GHz, 24.9 GHz, and 25 GHz and covers the wide range of frequency from 17.2 to 25.5 GHz which makes it applicable to function at the Ku and K band applications. Simulation of an antenna is done by Ansys HFSS 17.0 software. The results of the simulation show that the antenna has achieved a stable radiation pattern with an appreciable gain of 10 dB, peak directivity 4.26 dBi, peak gain 5.66 dBi, and a maximum bandwidth of 1 GHz with 98% radiation efficiency at these operating frequency bands.

Sigambra sundarbanensis sp. nov. (Annelida, Pilargidae) from the Indian sector of Sundarbans Estuarine System, with remarks on parapodial glands

A new pilargid species, Sigambra sundarbanensis sp. nov., is described from the rivers Matla and Thakuran, in the central Indian sector of the Sundarbans Estuarine System. This species is characterized by several characters such as the starting position of the notopodial hooks, the length of the median antenna and the variation in number of the neuropodial chaetae. These characters distinguish the new species from its congeners. Some parapodial glands have been found in individuals of this species. The new species closely resembles Sigambra parva (Day, 1963). Additionally, an updated key of genus Sigambra is provided, along with a table indicating their morphological variations and a global map showing their type localities.

Trait-density relationships explain performance in cladoceran zooplankton.

Traits have been used extensively to predict and understand performance in response to the abiotic environment, but their role for understanding competitive interactions is less understood, especially in nonplant systems. In this study, we evaluate how traits interact with intraspecific density to modulate performance (per capita birth rate) and whether the traits associated with intraspecific competitive ability are similar across multiple species. We used an experimental system of four cladoceran zooplankton species, experimentally manipulated the density of conspecifics, and measured a range of morphological and life history characteristics (body mass, body length, second antenna length, eye diameter, relative growth rate, age at first reproduction, and birth rate). With causal modeling, we identified significant trait-density relationships for three out of four species, although the specific traits that predicted birth rate varied from species to species. In general, individuals at higher densities displayed smaller morphological traits and shifts towards slower relative growth rates and delayed onset of reproduction. We also asked more generally if there are consistent trait-mediated impacts of density across multiple species. The interspecific model identified significant trait-density relationships for body length, age at first reproduction, and relative growth rate. Unexpectedly, we found little evidence for trait-based competition due to mechanisms such as limiting similarity or hierarchical competition, and rather noted the potential for trait plasticity and constraints on plasticity affecting performance in response to the competitive environment.

First report of morphometrics and length-length relationships of the common grass yellow butterfly, Eurema hecabe (L.) (Lepidoptera: Pieridae)

The present investigation was conducted to study the morphometrics and length-length relationships (LLRs) of the Common Grass Yellow Butterfly, Eurema hecabe (L.) (Lepidoptera: Pieridiae). Samples were collected randomly from the Rajshahi University Campus (RUC), Bangladesh, and the pictures were taken with a DSLR camera (Canon 750D) and measured using ImageJ software (l.48v). Here, a total of 14 different morphometric lengths viz. total body, antenna, wings (fore- and hindwing) and legs (fore-, mid- and hindleg) were evaluated. Total length (TL) was recorded as a minimum of 11.51 mm and a maximum of 22.01 mm, whereas antenna length (AL) has differed from 5.78-8.68 mm. The highest morphometric mean was found in forewing base-apex (FWBA) as 21.45±2.21 mm, and the lowest mean of length was recorded in the hindleg (HL) as 6.21±0.67 mm. The FWBA was larger than the TL about 33% followed by the forewing base-tornus (FWBT), hindwing base-apex (HWBA), hindwing base tornus (HWBT) and forewing cubitus2 vein (C2V). According to co-efficient of determination (r2) values, the best-fitted model of LLRs was TL vs. foreleg (FL) among 13 equations. The allometric coefficient ‘b’ was suggested positive allometric growth. These works will be very useful for species recognition and taxonomic study of butterflies in the RUC as well as in Bangladesh.

Abnormalities in two Bosmina longirostris s.l. (OF Müller, 1785) populations (Crustacea: Branchiopoda: Bosminidae)

Abnormal trunk morphology is observed in two populations of Bosmina longirostris. One population is from a trout cultivation pond, the other from a pond with a very high angling pressure. The length and shape of the first antenna (trunk) of part of the population are abnormal. No abnormalities were observed at three locations, with low or no angling pressure. The observations are considered in the context of the described variation in the first antenna of this species. Possible causes of the abnormalities are discussed.

A tapered CPW fed leaky‐wave antenna based on substrate integrated waveguide with reduced side‐lobe level

A novel method for confining the undesired radiation of the feed transition of a low-profile leaky-wave antenna (LWA) is demonstrated in this paper. The proposed design method uses novel tapered CPW transitions resulting in variation of the parasitic capacitance and electrical length of the feed. This leads to the reduction of the side-lobe level (SLL), which is dictated by the feed and the slotted sections of the antenna. The undesired radiation from the feed becomes crucial in the low-profile antenna in which the surface-mounted connector along feed transition is the only practical feeding mechanism. The key novelty of the proposed approach is the reduction of SLL by exclusively modifying the feed structure rather than the slotted radiation section. To validate the proposed approach, a modified compact feeding mechanism for LWA is designed. The antenna is realized based on the substrate integrated waveguide (SIW). The antenna's length, width, and height are 110 mm, 31 mm, and 0.5 mm, respectively. The operating frequency band was chosen as 26 to 30 GHz, covering an allocated 5G band. The measured peak realized gain and SLL are 6.1 dBi and − 11.4 dB, respectively. An improvement of 5.7 dB in SLL compared to the conventional LWA was observed. The simple fabrication process and efficiency of the proposed method make it a viable approach for reducing the SLL of the low-profile antennas. Compactness, low SLL, and proper gain of the reported antenna make it a suitable candidate for 5G vehicle to everything (V2X) communications and mm-wave navigation systems.

5G wideband on‐chip dipole antenna for WSN soil moisture monitoring

Recently, soil dielectric constant detection has been used in the irrigation of vastly differing farming conditions. Soil monitoring has seen a push toward fifth generation (5G) telecommunications technology, due to the higher speed and bandwidth required to connect a huge number of sensor nodes simultaneously. A novel architecture for a fully integrated, unequal arms dipole antenna is presented in this article. The proposed on-chip antenna is implemented using UMC180 nm CMOS technology. A dipole radiator is added on the upper metal layer, a ground sheet set at the lower metal layer and a patch layer is added on the intermediate metal layer. This configuration has improved the antenna impedance bandwidth by 38%. In addition, it increased the electrical length of the dipole antenna to reduce the antenna resonant frequency by 10 GHz. The proposed antenna has a total area 1300 × 250 μm, and its wide bandwidth extends from 21 to 40 GHz at reflection coefficient |S11| < –7 dB, which makes it suitable for on-chip wireless sensor network applications in 5G technology. All Simulations are completed by using the Ansys HFSS (high-frequency structure simulator) ver.15 and the simulated results show a good comparison with measurements. To investigate the proposed antenna's performance in different environmental conditions, practical measurements for soil dielectric constant in different compositions with variable moisture ratios are applied. The resulting values are used in antenna simulation and have ultimately proved the antenna's improved capability to sense soil moisture in different conditions.

Empidadelpha pokekeao (Diptera: Empididae): a new species from New Zealand

ABSTRACT Empidadelpha pokekeao sp. nov. (Empididae: Empidinae) is described from male specimens collected in native forest at Sullivan’s Dam, Dunedin, New Zealand and in snow tussock at Macraes Flat, New Zealand. The species is distinguished from other species of Empidadelpha by the colouration of the body and legs, the remarkable length of the male antenna, and the distinctively darkened wings with a large dark cloud anteroapically. The two only other New Zealand species of this genus, E. propria Collin, 1928 and E. torrentalis Miller, 1923, were also examined and are discussed here.

Reconfigurable SIW-Based Leaky-Wave Antenna Composed of Longitudinal Cells

A novel fixed frequency beam-steering leaky-wave antenna (LWA) is presented in this manuscript. Radiation occurs through thin offset longitudinal slots etched on a substrate integrated waveguide (SIW). The beam-steering is achieved by implementing GaAs varactor diodes on the backside of the antenna. Sweeping the bias voltage from 1V to 15V causes the phase constant variation, leading to the 25° beam-steering at 28.5 GHz. The key novelties of the proposed reconfigurable antenna are the low-profile and electronic beam-steering capability using a single varactor diode per cell located on the antenna's backside. Moreover, placing the components on the backside reduces the unwanted blockage effects on the radiation. The antenna's thickness, length, and width are 0.32 mm, 95 mm, 24 mm, respectively. The measured peak realized gain of the proposed antenna at 28.5 GHz is 9 ± 0.8 dBi. Low-profile, small gain variation, ease of fabrication, and electronic beam-steering capability make the proposed LWA suitable for the 5G beam-steering applications. A detailed sensitivity analysis along with the experimental validations were performed to prove the validity of the proposed novel design.

Performance of defected ground structure with miniaturized microstrip patch antenna using RMPA substrate material

Abstract A parallel structural antenna with the acts slot configuration is indicated for process of 5G wireless technology. The direct slot configuration defined within the patch antenna drives the 5G mid band and twin band frequency reaction in the frequency location without the conditions. Next, a 2-D Double Periodic Electronic Band (EBG) shape is carried out below the metal ground aircraft to request an extended impedance bandwidth for RMPA Materials. The slot duration and feature changed into designed for an impedance bandwidth of 12.49% and 4.49% at three pass band frequencies of 532 GHz and, 835 GHz respectively. Simulated with measured gain and reflection coefficient of correct settlement for bending bandwidths. The antenna array length is 33.5 mm × 33.5 mm. The antenna modified structure and the experimental effects were compared with all the other existing systems. The proposed antenna, which makes use of the EBG structure, suggests pics and excessive sensitivity steady with a massive impedance bandwidth, meeting the necessities of the IoT software program supplied with the resource of 5G technology.

Morphometric measurement of hog plum leaf beetle Podontia 14-punctata (Chrysomelidae: Coleoptera)

The objective of this article is to find out the morphometric measurement of Hog Plum Leaf Beetle Podontia 14-punctata (Chrysomelidae: Coleoptera). The result showed that the mean length and breadth of the 1st, 2nd, 3rd, 4th instars larvae were 1.93, 10.02, 12.0, 20.42 mm and 0.99, 1.48, 3.41, 6.55 mm respectively and the weight were 4.367, 24.695, 75.282, 315.7 mg respectively. The average length breadth and weight of male pupae were 12.7, 6.90 mm and 1.75 g, respectively and female pupae were 14.5, 8.5 mm and 2.272 g, respectively. The average length of antenna of male and female were 7.1 and 8.05 mm, respectively. The length of 3rd legs or long leg of male and female beetle was 12.0 and 13.1mm, respectively. The length of fore wing (elytra) and hind wing in male were 11.6 and 18.0 mm and female were 13.1 and 21.5 mm, respectively. The average length and breadth of abdomen of male and female were 9.2, 7.05 mm and 11.1 and 7.6 mm respectively. The length of head of male and female were 5.0 and 5.6 mm, respectively.

Graphene characterization based nano dipole antennas design for nano network wireless communication applications

Graphene-enabled nano antennas constitute a novel paradigm which is a current trend of research among designers. Graphene-based nano-antennas with nanometer in size have shown to radiate electromagnetic waves at the terahertz (THz) frequency band. Proposed research activity is an attempt of Terahertz Nano dipole antenna design through the Finite Difference Time Domain (FDTD) based numerical simulation software, i.e. CST. Graphene material as adipole antenna has been explored to get a radiation performance. Before hand absorption, reflection and transmission characteristics of the grapheme layer has been explored. Designed antenna is analyzed in terms of the reflection coefficient, and radiation pattern etc. An attempt has been done for resonance study of graphene based nano dipole antennas, in that patch antenna length parameteris changed and performance is observed. The impact of most crucial parameter, i.e., chemical potential on the grapheme radiation performance has been analyzed in terms of reflection coefficient. Proposed antenna may be suitable for wireless nano communication applications.

Propagation of Surface Plasmon Waves along Multi Wall Carbon Nanotube with Gold Core

We have studied the propagation of surface plasmon waves along multiwalled carbon nanotube with gold core. We have modeled the shells of multiwalled carbon nanotube as impedance sheets with axially directed surface conductivity incorporating inter shell coupling in an integral equation approach. We have found that in low frequency regime optical interband transitions did not occur and guided waves propagated with low attenuation in an multiwalled carbon nanotube which has metallic shells. In the same frequency range the axial polarizability of a finite length multiwalled carbon nanotube has a resonant behavior due the antenna length matching effect. The shells with surface conductivity due to interband transitions suppressed guided wave propagation. Surface Plasmon wave propagation in a multiwalled carbon nanotube with gold core showed that in the near infrared and visible regime the shells behaved as lossy dielectric materials and suppressed surface wave propagation along the gold core. The electromagnetic characteristics of carbon nanotube based antennas have been examined in different frequency regime ranging from the microwave to the visible regime. Carbon nanotube has been demonstrated to play a crucial role connected electrically to planner periodic structures of single wall carbon nanotubes, carbon nanotube bundles and carbon nanotube arrays. The inter shells interaction leaded to inter shell electron tunneling or hopping. Fermi momentum of two incommensurable shells do not coincide within the first Brillouin zone and the inter shell tunneling vanished. In the presence of localized defects inter shell conduction increased and defectfree shells were managed by neglecting intershell conduction. We have used microscopic model for multiwalled carbon nanotube and radiation characteristics were determined by its waveguiding properties, the dispersion equation for guided wave propagation on an infinitely long multiwall carbon nanotube. We have found that the guided wave has strong retardation and high attenuation so that the frequency of a geometric resonance is not connected to the free space wave length but to a shorter effective wavelength that depends on the material properties. The obtained results were compared with the previously obtained results and were found in good agreement.

Hexagonal ring microstrip patch antennas for PCS and S-band radar applications

In this study, two hexagonal ring microstrip patch antennas for Personal Communication Service (PCS/1850-1990 MHz) and S-band (2000-4000 MHz) radar applications are proposed and simulation results for antenna performance parameters are presented. The antennas consist of a hexagonal ring patch, a ground plane and a dielectric substrate in between. Edge length of each square antenna is 25 mm. Substrate height is 4.3 mm. Relative permittivity and loss tangent of the substrate material are 15.5 and 0.0001, respectively. Distance from center of the antennas to inner and outer hexagon corners are 4 mm and 10.19 mm, respectively. The antennas are fed by a 50-ohm coaxial probe. Depending on the feed location, resonant frequency and therefore application choice is achieved. Center of the antennas is denoted as (0, 0) mm. For the feed location of (-1.50, -4.19) mm, the antenna for PCS application resonates between 1830-2035 MHz with a bandwidth of 205 MHz. Voltage Standing Wave Ratio (VSWR) value at 1900 MHz is 1.1097. Unidirectional radiation patterns are obtained for both Ø=0ᴼ and Ø=90ᴼ planes. Maximum radiations occur at boresight with radiation levels of 12.09 dB and 12.10 dB for Ø=0ᴼ and Ø=90ᴼ planes, respectively. Maximum gain is 3.26 dBi for Ø=0ᴼ plane and 3.09 dBi for Ø=90ᴼ plane. For the feed location of (-7.36, 0.95) mm, the antenna for S-band application resonates between 3280-4015 MHz covering S-band with a bandwidth of 735 MHz. The frequency range and bandwidth are suitable for the radar application. VSWR value at the resonant frequency of 3650 MHz is 1.0164. Again, unidirectional radiation patterns are obtained for both Ø=0ᴼ and Ø=90ᴼ planes. Maximum radiations occur at boresight with radiation levels of 5.82 dB and 5.75 dB for Ø=0ᴼ and Ø=90ᴼ planes, respectively. Maximum gain is 4.14 dBi for Ø=0ᴼ plane and 4.03 dBi for Ø=90ᴼ plane.

One-Sixteenth Spherical Homogeneous Dielectric Lens Antenna Using Partially Reflective Surface for Size Reduction and High-Gain Radiation

Size reduction of a 1/16 spherically sectoral homogeneous dielectric lens antenna is developed in this letter by integrating a planar partially reflective surface (PRS) to produce high-gain radiation. Such a PRS, optimized by a full-wave simulator and the geometrical optics (GO) ray tracing method, has replaced the external longitude portions of ground planes in the original sectoral lens antenna to make an aperture size of 11 × 15 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which reduces the radius of the spherical dielectric lens by more than 33.3% (from 6 to 4 cm). The overall antenna length is reduced by 56% (from 15 to 6.59 cm). The PRS plate with a ground plane is designed by ray tracing to reach a relatively uniform field distribution on the PRS aperture for high-gain radiation. An antenna gain of 18.94 dBi has been achieved at 9 GHz from a sectoral lens fabricated by a 3-D printer using ABS (ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> = 2.429) material. The design was well validated by both numerical simulations and measurements with good agreement.

A New Species of Freshwater Amphipods Echinogammarus (Amphipoda, Gammaridae) from Algeria

Several samples of amphipods were obtained from six stations in the upper reach of the Youkous Stream, near Hammamet. This study describes a new species, Echinogammarus monodi n.sp., differing from other Echinogammarus species in the length of the first antenna, the setation of the third article of the mandibular palp (bearing three rows of A-setae and two rows of B-setae), the merus and carpus of pereopods 5 with long setae only, and the exopodite of uropod 3 with numerous groups of long simple setae. A full description of the new species and information about its distribution is given in this paper.

Patch-Antenna-Based Structural Strain Measurement Using Optimized Energy Detection Algorithm Applied on USRP

A new structural health monitoring (SHM) program using spectrum sensing and radio-frequency identification technology is presented to measure structural strain. The proposed program involving universal software radio peripheral (USRP) provides an economical alternative to these type of measurements as compared to high-end equipment while this method can achieve more flexible data processing. The overall system for strain detection consists of three main parts: 1) a patch antenna as the sensor for strain; 2) an USRP as a measuring instrument; 3) a computer for data processing. The patch antenna can be used to measure structural strain by interrogating resonant frequency shift due to changes in antenna length. In this article we use the optimized energy detection algorithm applied on USRP to detect the spectrum of the patch antenna, the final measurement results show that the patch antenna sensor has a strain sensitivity 1.7678 kHz/ $\boldsymbol{\mu } \boldsymbol{\varepsilon }$ while the error between the measured value and the true value of the stress is 2.443% after corrected by machine learning.

Side-Lobe Level Reduction of Half-Mode Substrate Integrated Waveguide Leaky-Wave Antenna

In this communication, we introduce a novel design for mitigating the side-lobe level (SLL) of the half-mode substrate integrated waveguide (HMSIW)-based leaky-wave antenna (LWA). Applying a novel approach through modification of the side aperture of HMSIW, we achieved an SLL of −13.8 and −11.2 dB in the upper hemisphere and full space, respectively. The key novelty of this communication is the reduction of SLL in full space while the state-of-the-art antennas only mitigated the SLL in the upper hemisphere. Furthermore, tapering the open side aperture in a thin trapezoid shape led to a significant reduction of beam squint. The operating frequency band of the antenna matches the allocated 5G wireless network millimeter-wave bands from 26 to 30 GHz. The measured peak realized gain of the antenna is 10.6 dBi at 28.5 GHz. The length, width, and height of the HMSIW antenna are 70, 15, and 0.5 mm, respectively. The antenna was fabricated on a Rogers RT/Duroid 5880 substrate. Excellent agreement between the measurements and simulated results was observed. The discrepancies between the measured and simulated results were analyzed by a complete and thorough sensitivity analysis that included the effects of the fabrication tolerances, connectors’ misalignment, and bending due to the mechanical stress. High gain, low SLL, and compactness are among the advantages of the proposed antenna making it a suitable candidate for the miniaturization of 5G communication systems.

An Ultrawideband and High-Gain Antenna Based on 3-D Impedance-Matching Metamaterial Lens

In this article, we present an ultrawideband and high-gain antenna based on a 3-D impedance-matching metamaterial (IMM) lens. First, we design a 3-D IMM lens which can convert spherical-like waves to plane ones and is nearly perfect impedance-matching with the free space. To realize the 3-D lens, we propose and design two kinds of ultrawideband sandwich-structured metamaterial unit cells that can cover the refraction index ranges from 1.25 to 1.4 and from 1.4 to 3.8, respectively. We also design a double-ridged pyramid horn antenna as an ultrawideband feed source. Measured results verify that the presented lens antenna can work in an ultrawide bandwidth from 5.2 to 15.13 GHz, and the relative bandwidth is 97.7%. Moreover, it achieves a high aperture efficiency of more than 66% from 5.2 to 14.3 GHz, with a relative bandwidth of 93.3%. A maximum aperture efficiency of 85.6% is obtained at 11.5 GHz. The proposed lens antenna has an average of 2 dB gain enhancement versus optimal horn with the same aperture area. And the length of the lens antenna reduces to 22% compared to a bare horn antenna with the same gain and aperture efficiency.

Secure transmission for heterogeneous cellular network with limited feedback

We study physical layer secure transmission with limited feedback in heterogeneous cellular networks. A transmission protocol is designed to obtain more secure and accurate channel state information (CSI) for enhancing the secrecy performance. Under the proposed protocol, we derive expressions of coverage probability and secrecy outage probability to analyze the security performance with different system parameters such as feedback CSI length and number of antennas. Furthermore, an iteration algorithm is proposed to balance the tradeoff between the feedback and transmission time, and maximize the average secrecy throughput under coverage and secrecy outage constrains. Numeric results demonstrate the optimal feedback overhead and the maximum average secrecy throughput are influenced by the number of antennas.