Antenna Size Research Articles

Design of Circular Patch Array Microstrip Antenna Using Slot for ISM Band

This paper presents a Microstrip Antenna Analysis for the ISM Band with a circular patch design with a radius of 17 mm at a frequency of 2,400 – 2.484 GHz. The fabricated array antenna has a very compact width and length of 9.5 x 7.5 cm each. Therefore, an increase in bandwidth on the monopole antenna can be applied to the array arrangement. So to get the best antenna design, two optimizations of antenna size changes are carried out during the simulation: optimization of patch radius and slot length. The radius variation is used to shift the frequency range and slot length for impedance matching, as seen from the S11 value of less than -10 dB. From each change, the best results are taken. Experiments get the best antenna simulation results and are then fabricated. From the measurement results on the fabricated antenna, the lowest S11 value is -19.602 dB, and the gain is 3.52 dBi. The slot technique's optimization process has successfully shifted the frequency to approximately 100 MHz and increased the bandwidth by about 5% or 40 MHz.

Development of a compact transverse slot array antenna using corrugation in groove gap waveguide technology

SummaryWe present the proof of concept of a compact slot array antenna with proper side lobe level in groove gap waveguide (GGW) technology. Four transverse slots are etched at the GGW broad wall along with the nulls of standing TE10 wave existing inside the shorted GGW. To decrease the sidelobes and antenna size, corrugations are applied through the wave path inside the GGW. Proper use of corrugations can reduce the wavelength inside the GGW leading to reduction of the distance between adjacent transverse slots, which can help to suppress the grating lobe problem and consequently enhance the radiation efficiency, which is a challenge in transvers slot array antennas. The designed antenna is optimized to achieve maximum gain, lowest grating lobe level, and return loss at 15 GHz using HFSS simulator. The achieved gain is about 13 dBi, and the SLL is better than 15 dB. To confirm the simulation results, the designed antenna was fabricated and tested. Both simulation and measurement results confirm that the grating lobes are well suppressed at the antenna operating frequency.

Photosynthetic apparatus of barley plants treated with 5-aminolevulinic acid: mechanisms of adaptation to drought

A significant effect of soil drought on the morphometric parameters of the leaves of barley plants of the Brovar and Avans varieties, the accumulation of reactive oxygen species, as well as the content of photosynthetic pigments in them has been established. It has been shown that during drought, the treatment of leaves of barley plants of the Brovar variety with 5-aminolevulinic acid causes a decrease in the content of proteins of photosystem antenna complexes, which leads to a decrease in the size of the light-harvesting antenna and is an effective mechanism for protecting the photosynthetic apparatus from oxidative stress. Fine adjustment of the photosynthetic apparatus components of leaves of barley plants ofthe Brovar variety to drought may be a key factor in determining the resistance of this variety to this type of abiotic stress. In the Avans variety, these adaptation mechanisms are either absent or manifest to a lesser extent, which leads to a more intensive development of oxidative stress in plants of this variety under the action of soil drought.

Design and analysis of broadband circularly polarized compact planar antennas for 2.45 GHz RFID handheld reader applications

AbstractIn this article, an innovative design of a broadband circularly polarized compact planar antenna for RFID (radio frequency identification) receivers is presented. The suggested structure used the concept of slots loaded parasitic element printed underneath a coplanar waveguide-fed radiator to achieve the circularly polarized (CP) radiation and size reduction. A parasitic element loaded with F-slot and L-slot, and a window-type slotted ground plane was used to achieve resonance at 2.45 GHz with right-handed circularly polarized radiation for RFID handheld reader application. Experimental results confirmed that the designed antenna of size 16.5 × 14.8 × 1.6 mm3 attained a −10 dB impedance bandwidth of 15.8% (from 2.330 to 2.716 GHz) and 3 dB AR bandwidth of 3.43% (from 2.410 to 2.494 GHz). An axial ratio of 0.43 dB was achieved in the boresight of the antenna at the 2.45 GHz RFID band. The concept of electric field distribution on the antenna was used to elaborate the excitation of CP radiation in the antenna.

Extra‐large MIMO enabling slow fluid antenna massive access for millimeter‐wave bands

Fluid antenna multiple access (FAMA) is a new way of accommodating a large number of users on a single channel for massive connectivity, with slow FAMA (s-FAMA) being the practical version for achieving this. The impressive performance is understood to be achievable if the users have independent Rayleigh fading envelopes. With mobile networks vamping up the operating frequencies in 5G and beyond, nevertheless, the channel will have less multipath and become more directional. It is unclear if s-FAMA still performs well and how its performance is affected by different channel parameters. To address this, this letter first develops a multipath fading channel model capable of modelling a mixture of directional line-of-sight (LoS) and non-LoS paths over the ports of a fluid antenna system. The results indicate that a large number of paths in the channel is essential to the performance and a large Rice factor will degrade the performance rapidly. Also, contrast to the initial belief, the size of the fluid antenna plays a more important role than the number of ports or resolution of the fluid antenna. To restore the gain of s-FAMA, it is proposed to employ extra-large multiple-input multiple-output (XL-MIMO) at the base station (BS) to scramble the channel and create artificial multipath so that the users' envelopes can become independent Rayleigh again. The results confirm that XL-MIMO enabling s-FAMA is an effective technique for massive connectivity in the directional millimeter-wave (mmWave) bands.

Compact Wide-Beam Circularly Polarized End-Fire Antenna Combining Ground Radiation Mode and Vertically Polarized Mode

A compact wide-beam endfire antenna with ground radiation mode and vertically polarized mode for circular polarization (CP) is presented in this article. The antenna is constructed based on a configuration of coupled-mode patch antenna (CMPA), which consists of two coupling cavities with a shorting wall, and can generate vertically polarized modes. The CP is realized through a pair of orthogonally polarized modes of horizontal and vertical polarizations. Meanwhile, rendering them acquires an equal amplitude and a 90° phase difference. The horizontally polarized radiation mode is realized through inserting a crossed ground slot. Offset probe feed is used to excite all the radiation modes and introduce an additional phase shift for the CP. A set of offset ground slots (OGSs) are then applied to perturb the electromagnetic coupling of the modes and adjust the phase and magnitude of the radiating electric fields (E-fields). Several effects are synthesized, which results in a wide-beam circularly polarized (CP) endfire radiation. Aiming to improve the radiation performances, a cavity-backed planar reflector was applied in the experiment. Simulated and measured results are detailed and analyzed, which demonstrate that the measured 3 dB axial ratio (AR < 3 dB) bandwidth (ARBW) ranges from 3.385 to 3.428 GHz (1.2%), and the peak gain can be up to 3.4 dBi if the planar reflector is added. The measured half-power beamwidth (HPBW) and 3 dB ARBW can be up to 88°/114° and 53°/112° at 3.4 GHz, respectively. The antenna size (excluding the reflector) is maintained at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.49\lambda _{0}\times 0.25\lambda _{0}\times 0.017\lambda _{0}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the wavelength in free space, performing a compact configuration.

Miniaturized Broadband Dual-Polarized Dipole Antenna Based on Multiple Resonances and its Array for Base-Station Applications

A novel bandwidth enhancement method using loading multiple parasitic structures to realize broadband miniaturized antenna is proposed. Based on the proposed strategies, one miniaturized wideband dual-polarized dipole antenna covering LTE/CDMA/GSM bands (690–960 MHz) for base-station application is designed. The antenna consists of two folded bowtie-shaped dipoles fed with a pair of crossed baluns, and is further loaded on a ceramic block with high permittivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon$ </tex-math></inline-formula> ) for miniaturization. A parasitical square loop is loaded for bandwidth enhancement at a lower frequency. In addition, four split rings with a small square loop are firstly adopted for antenna resonance tuning, the impedance bandwidth is thus improved effectively. The antenna size is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18\,\times \,0.18\,\times \, 0.22\,\,\lambda _{0}$ </tex-math></inline-formula> at the center frequency. The measured result of the fabricated prototype exhibits a relatively large operation bandwidth of 32.73% (VSWR < 1.6) with stable radiation patterns and relatively flat broadside gains. Moreover, to verify the feasibility of the proposed miniaturized antenna element in the base-station application, an array of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\,\times \, 4$ </tex-math></inline-formula> is further designed. The measured results of the array indicate isolation over 20 dB with an impedance bandwidth of 32%. Due to the good performance and compact feature, the proposed miniaturized broadband antenna element can find large application potential in multiband wireless communication base stations.

Miniaturization and Cross-Polarization Reduction of Quarter-Wave Microstrip Antennas Based on Magnetic Currents Reconstruction

In this work, a simple method is proposed to simultaneously reduce the size and cross-polarization level (XPL) of quarter-wave microstrip antennas by reconstructing the magnetic currents along the radiation edges. A design example of five shorted elements is given with a comparison of the quarter-wave microstrip antennas at 1.88 GHz. Measured results show an over 64% size reduction and 17-dB cross-polarization suppression enhancement for the proposed scheme as compared with the conventional one. Moreover, the proposed scheme exhibits good broadside radiation patterns with a gain of 5.4 dBi and the half-power beamwidths of about 104° in the E-plane and 84° in the H-plane.

Manganese Limitation of Phytoplankton Physiology and Productivity in the Southern Ocean.

Although iron and light are understood to regulate the Southern Ocean biological carbon pump, observations have also indicated a possible role for manganese. Low concentrations in Southern Ocean surface waters suggest manganese limitation is possible, but its spatial extent remains poorly constrained and direct manganese limitation of the marine carbon cycle has been neglected by ocean models. Here, using available observations, we develop a new global biogeochemical model and find that phytoplankton in over half of the Southern Ocean cannot attain maximal growth rates because of manganese deficiency. Manganese limitation is most extensive in austral spring and depends on phytoplankton traits related to the size of photosynthetic antennae and the inhibition of manganese uptake by high zinc concentrations in Antarctic waters. Importantly, manganese limitation expands under the increased iron supply of past glacial periods, reducing the response of the biological carbon pump. Overall, these model experiments describe a mosaic of controls on Southern Ocean productivity that emerge from the interplay of light, iron, manganese and zinc, shaping the evolution of Antarctic phytoplankton since the opening of the Drake Passage.

Light-induced damage to photosystem II at a very low temperature (195 K) depends on singlet oxygen.

Photosynthetic organisms, like evergreen plants, may encounter strong light at low temperatures. Light, despite being the energy source of photosynthesis, irreversibly damages photosystem II (PSII). We illuminated plant thylakoid membranes and intact cyanobacterial cells at -78.5°C and assayed PSII activity with oxygen evolution or chlorophyll fluorescence, after thawing the sample. Both UV radiation and visible light damaged PSII of pumpkin (Cucurbita maxima) thylakoids at -78.5°C, but visible-light-induced photoinhibition at -78.5°C, unlike at +20°C, proceeded only in the presence of oxygen. A strong magnetic field that would decrease triplet chlorophyll formation by recombination of the primary radical pair slowed down photoinhibition at -78.5°C, suggesting that singlet oxygen produced via recombination of the primary pair is a major contributor to photoinhibition at -78.5°C. However, a magnetic field did not affect singlet oxygen production at +25°C. Thylakoids of winter leaves of an evergreen plant, Bergenia, were less susceptible to photoinhibition both at -78.5°C and +20°C, contained high amounts of carotenoids and produced little singlet oxygen (measured at +20°C), compared to thylakoids of summer leaves. In contrast, high carotenoid amount and low singlet oxygen yield did not protect a Synechocystis mutant from photoinhibition at -78.5°C. Thylakoids isolated from Arabidopsis thaliana grown under high light, which reduces PSII antenna size, were more resistant than control plants against photoinhibition at -78.5°C but not at +20°C, although carotenoid amounts were similar. The results indicate that visible-light-induced photoinhibition at -78.5°C depends on singlet oxygen, whereas photoinhibition at +20°C is largely independent of oxygen.

MIMO antenna array with the capability of dual polarization reconfiguration for 5G mm-wave communication

This communication presents a polarization reconfigurable antenna array (PRAA) with Multi-input Multi-output (MIMO) formation for 5th generation (5G) millimeter wave (mm-Wave) communications. At first a single corner curtailed diagonal slotted cylindrical patch is printed on Roger RT Duriod 5880 and the overall size of the single antenna is 12 × 12 × 0.787 mm3. The circular polarization (CP) is realized by adding the diagonal slot in the circular patch. The antenna design is extended into two elements antenna array which occupies 20 × 20 × 0.787 mm3 footprint. The collection is formed using a T-shaped power divider/combiner. Pin-diodes are integrated with the patches to switch the polarization state between LP (Linear polarization) and CP radiation. The edge-to-edge distance between antenna elements is 6 mm. The design covers the 25.2–29.4 GHz band, and the maximum peak gain is 11.5 dBi. Moreover, a two-port (2 × 2) MIMO design is formed to increase the channel capacity. To isolate the ports, a sin-like slot is engraved in the ground, defected ground structure (DGS) technique of mutual coupling reduction; it can easily be implemented and increases the design efficiency. The port isolation is well above 30 dB for the entire operating band. Moreover, the Mean Effective Gain (MEG), Diversity Gain (DG), and Envelope Correlation Coefficient (ECC) are investigated, which are key performance metrics of MIMO. A prototype of the realized MIMO antenna system is fabricated, and the simulated outcomes carried out by Computer Simulation Technology (CST) tools are validated by experimental findings.

Miniaturized wideband implantable slotted loop antenna for biotelemetry applications

Abstract Small size of the implantable antenna is the major concern in Implantable Medical Devices. A compact implantable wideband radiator working at the ISM band is proposed for biotelemetry applications. The overall dimension of the proposed radiator is 10 mm ⁎ 15 mm ⁎ 0.8 mm and the thickness includes substrate and superstrate thickness. The Coaxial feeding method is employed here. The inner and outer diameter of the coaxial feed is 1 and 1.5 mm respectively. The design process starts with a creation of rectangular patch of size 10 mm ⁎ 15 mm and the coaxial feed is located at (2.5, 7). Then slot like loops are introduced on a rectangular patch. This compact size is achieved by introducing small loops on a rectangular patch along with triangular cuts at the bottom right and top-left of the patch. The antenna is simulated with a tissue model (Skin, Fat, Muscle, Bone) and measured with a Body Equivalent Fluid (phantom). The −10 dB bandwidth is obtained over 1340 MHz (1.66–3 GHz) and the fractional bandwidth of 54.7% at the ISM band. The simulated gain and radiation efficiency of the radiator are −13.5 dBi and 3.15% respectively. The measured return loss of the proposed antenna is −30.53 dB and the SAR value averaged over 1 g tissue is 302.6 W/kg with 1 W input power. When compared to the previous works mentioned in the literature the proposed antenna displays wider bandwidth, high gain, low SAR and high radiation efficiency.

Particle Swarm Algorithm Based on Homogenized Logistic Mapping and Its Application in Antenna Parameter Optimization

Aiming at the problems of computing complexity, long time-consuming and low accuracy in the process of antenna optimization design, a particle swarm optimization algorithm based on chaotic ergodic search is proposed in this paper. In order to improve the rationality of the selection of the initial population of the traditional particle swarm optimization algorithm and enhance the diversity of particles in the iterative process of the algorithm, this algorithm introduces a uniform Logistic chaotic map into the traditional particle swarm optimization algorithm, so as to improve the convergence speed and optimization performance of the particle swarm optimization more effectively. In this paper, the Logistic map is selected in the chaotic map, and the analysis shows that although it has good long-term periodicity and initial value sensitivity, the data does not obey the uniform distribution, which makes the omission range when the sequence value is small, which reduces the chaos. The efficiency of traversal, in view of this shortcoming, this paper proposes a method of homogenizing Logistic, and deduces and analyzes it. It is concluded that this homogenized Logistic method has better randomness and can better reflect the characteristics of uniform distribution of data. Further, based on the optimization algorithm, the rectangular microstrip antennas with two feeding modes are optimized, and the antenna size obtained by empirical formula is modeled and analyzed in HFSS software. The research results show that the optimization algorithm in this paper can bring faster convergence speed and more accurate optimization results for antenna optimization.

Genetic algorithms for the design of planar THz antenna

This paper proposes a genetic algorithm for the design of passive components operating at THz frequencies and its experimental validation using an exemplar patch antenna. The patch antenna is based on an SU8 substrate, with a binary array describing the placement of metal “bits” replacing the conventional patch. These “bits” are constrained at 25 × 25 μm2, ensuring ease of fabrication. Optimal configurations of this array are determined using a finite-difference time-domain solver coupled to the genetic algorithm, which simulates and optimizes for maximum power collection in the frequency range of 0.10–5.0 THz. The aim was to produce an evolved patch antenna design with double the power collection efficiency across the majority of the frequency range compared to a reference, plain patch antenna of the same size. This was successful with a 5.3 dB mean improvement in simulated power collection compared to a plain reference patch. A vector network analyzer in conjunction with 0.80–1.0 THz frequency extenders was used to validate the simulation results. The antennas were arranged in pairs with variable feed length to determine the feedline attenuation and validate the simulated antenna directionality.

A VHF Band Small CRLH Antenna Using Double-Sided Meander Lines

In this paper, a miniaturized very-high frequency (VHF) band antenna using both top and bottom meander lines is proposed. To design a compact size antenna in the VHF band, a Composite Right/Left-Handed (CRLH) transmission line is applied to antenna structure; additionally, both top and bottom meander lines were used to achieve a greater inductance. The CRLH transmission line unit cell operates at 88 MHz, and the fabricated antenna is designed by arranging 7-unit cells. The overall size of the proposed antenna is 0.087λ × 0.02λ × 0.0003λ at the lowest operating frequency, and the antenna operates at 84 MHz. The VSWR 3.5:1 reference operating bandwidth of the antenna is 2%. The received power of the proposed CRLH antenna was measured to verify the antenna performance.

Modeling of a Compact Dual Band and Flexible Elliptical-Shape Implantable Antenna in Multi-Layer Tissue Model

A flexible antenna of compact size with a dual band elliptical-shape implantable is designed for biomedical purposes. The suggested antenna has an elliptical shape to be more comfortable for being implanted in human tissue. The implantable antenna is printed on RO3010 substrate with 2 mm as a thickness and 10.2 as a dielectric constant. It consists of an active planar C-shaped element and a parasitic planar inverted C-shaped element. The proposed antenna is designed with a major axis radius of 12 mm and a minor axis radius of 8 mm. It operates in dual bands: The Industrial Scientific and Medical band (ISM) [2.4 GHz–3.5 GHz] and Medical Implant Communications Service band (MICS) [394 MHz–407.61 MHz]. A short-circuited pin is used to minimize the antenna’s overall size and for further size reduction a capacitive load is used between the radiator and the ground plane. For biocompatibility, a thin-thickness layer of Alumina is used as a superstrate. The suggested antenna is tested in a multi-layer tissue model and the Specific Absorption Rate (SAR) value is computed. The proposed antenna was fabricated, and the reflection coefficient is measured and compared with simulated results.

Environmentally relevant copper concentrations stimulate photosynthesis in Monoraphidium sp.

Microalgae require copper (Cu) in trace levels for their growth and metabolism, it is a vital component of certain metalloproteins. Although this element has been widely studied concerning microalgae physiology, the effects of environmentally relevant levels have been less studied. We studied the photosynthesis and growth of the Chlorophyte Monoraphidium sp. exposed to Cu ranging from low (1.7nM) to high (589.0nM) free Cu ions (Cu2+) concentrations. The growth rate was unaffected by Cu concentrations in the range of 1.7-7.4nM Cu2+, but decreased beyond it. The relative maximum electron transport rate (rETRm), saturation irradiance (Ek), photochemical quenching (qP and qL), and PSII operating efficiency [Formula: see text] were stimulated in the 3.4-7.4nM Cu2+ range, concentrations slightly higher than the control, whereas non-photochemical quenching (NPQ) gradually increased with increasing Cu2+. The photosystem II antenna size [Sigma (II)440] increased under high Cu (589.0nM), which resulted in a decrease in the quinone A (QA) reduction time (tau). In contrast, the QA re-oxidation time was unaffected by Cu exposure. These findings show that a slight increase in Cu stimulated photosynthesis in Monoraphidium sp., whereas high Cu reduced photosynthesis and increased the dissipation of captured light energy. This research is a contribution to the understanding of the dynamic photo-physiological responses of Monoraphidium sp. to Cu ions.

Design of a metasurface filtering antenna with tunable radiation nulls

In this article, a low profile wideband metasurface filtering antenna with tunable radiation nulls is proposed. Metasurface structure is used to excite adjacent resonant modes to obtain broadband responses. A U-shaped slot is introduced into the microstrip line to generate a radiation null in the lower stopband. Complementary split-ring resonators (CSRRs) are etched on the metasurface unit to produce another radiation null in the upper stopband edge to improve the filtering effect. The radiation nulls position can be flexibly controlled by changing the size of U-shaped slot and CSRRs. For verification, the corresponding antenna is fabricated and tested. The antenna size is 0.556 λ 0 × 0.556 λ 0 × 0.044 λ 0 (30 × 30 × 2.4 mm3). The measured results agree well with the simulated. The antenna operates from 4.9 to 6 GHz with a flat gain (5.5 dBi), a sharp passband skirt and stable radiation patterns.

Design of multi-band and high radiation intensity piezoelectric antenna based on external circuit

AbstractThis paper presents a novel method to improve the working bandwidth and radiation intensity of piezoelectric antenna by using external circuit. This method makes the piezoelectric antenna combined with roles of high radiation intensity and multiple resonant frequencies without changing the structural size of the piezoelectric antenna. The experimental results show that, compared with the original piezoelectric antenna, the tuning range of the resonant frequency of the piezoelectric antenna caused by the series capacitance and inductance is +13.6 and −24%, respectively. The series inductance will produce new resonance frequency, which provides a new method for the multi-band operation of the piezoelectric antenna. The LLC (series and parallel circuit) composite circuit can increase the number of resonant frequencies of the piezoelectric antenna from 1 to 3, and the S11 at the resonant frequencies are all lower than −10 dB, and the radiated magnetic field of the piezoelectric antenna is increased by 42.3% at least. This method makes the piezoelectric antenna have the dual functions of high radiation intensity and multi-band, which has great significance for broadening the application field of piezoelectric antenna.

A Compact Low-Profile Antenna for Millimeter-Wave 5G Mobile Phones

This paper presents a very low profile and simple antenna design for dual beam and dual-band operation to be employed in future 5G mobile phones operating in the millimeter-wave bands of 26.75–30.31 and 35.83–41.22 GHz. The two distinct resonances at 28 and 38 GHz are achieved using a meta-material-based structure consisting of a closed-ring resonator (CRR) and a split-ring resonator (SRR) by co-centrically combining two planar hexagonal rings; i.e., an inner split-ring resonator (SRR) and an outer closed-ring resonator (CRR). The antenna has a high gain of 4.5 dBi. The antenna also exhibits a dual-beam radiation pattern in one of its planes. The overall antenna size is 6 × 8 mm2 and is manufactured using a low-cost PCB fabrication process. The antenna’s dual-beam operation, broadband characteristics, high gain, and low profile makes it a potential candidate for future millimeter-wave mobile phones, especially in applications where space diversity is required.