Antenna Size Reduction Research Articles

Proposal of a New Planar Micro-Antenna in LTCC Substrate for System on Chip

In this paper some parameters are combined to obtain an efficient antenna miniaturization that could be suitably used in systems on chip applications. Theses parameters are geometries in ring, slot and gap, commonly applied in size reduction of planar antennas. As an important element in sensor networks, the antenna should be compact and lightweight, and have high efficiency and low power consumption. To be well integrated (adapted and matched to the sensor circuits) the antenna design was made in LTCC (Low Temperature Co-fired Ceramic) substrate. The simulations with commercial software are compared with measurements presenting good results. The examples presented suggest the design of new types of structures. The results can be used as a first step guide to design miniaturized patch antennas.

Design of a compact broadband microstrip patch antenna with probe feeding for wireless applications

In this paper the design and development of a compact broadband probe-fed Microstrip patch antenna for bandwidth improvement and antenna size reduction in a single design is proposed. The well-known technique of effective substrate thickness increment is performed to improve the impedance bandwidth, whereas for size reduction the electrical length of the conducting patch has been increased. A compact probe-fed inverted U-shaped microstrip patch antenna with a W-shaped ground plane has been designed and the experimental results are presented.

Integration of Carbon and Nitrogen Metabolism with Energy Production Is Crucial to Light Acclimation in the CyanobacteriumSynechocystis

Light drives the production of chemical energy and reducing equivalents in photosynthetic organisms required for the assimilation of essential nutrients. This process also generates strong oxidants and reductants that can be damaging to the cellular processes, especially during absorption of excess excitation energy. Cyanobacteria, like other oxygenic photosynthetic organisms, respond to increases in the excitation energy, such as during exposure of cells to high light (HL) by the reduction of antenna size and photosystem content. However, the mechanism of how Synechocystis sp. PCC 6803, a cyanobacterium, maintains redox homeostasis and coordinates various metabolic processes under HL stress remains poorly understood. In this study, we have utilized time series transcriptome data to elucidate the global responses of Synechocystis to HL. Identification of differentially regulated genes involved in the regulation, protection, and maintenance of redox homeostasis has offered important insights into the optimized response of Synechocystis to HL. Our results indicate a comprehensive integrated homeostatic interaction between energy production (photosynthesis) and energy consumption (assimilation of carbon and nitrogen). In addition, measurements of physiological parameters under different growth conditions showed that integration between the two processes is not a consequence of limitations in the external carbon and nitrogen levels available to the cells. We have also discovered the existence of a novel glycosylation pathway, to date known as an important nutrient sensor only in eukaryotes. Up-regulation of a gene encoding the rate-limiting enzyme in the hexosamine pathway suggests a regulatory role for protein glycosylation in Synechocystis under HL.

Size reduction and bandwidth enhancement of snowflake fractal antenna

A new small-size and wideband fractal antenna in the shape of a snowflake is proposed. Various iterations of this fractal antenna with probe feed and capacitively coupled feed are compared and an optimised design is presented. It is shown that, with an air-filled substrate and capacitive feed, an impedance bandwidth >49% and, with a slot-loading technique, a reduction of about 70% in patch surface size compared with an ordinary wideband Koch fractal antenna are achievable. The simulation via a finite-element programme, and measured results on the return loss and the E and H-plane radiation patterns of the proposed antennas are presented and shown to be in good agreement.

A PRACTICAL MINIATURIZED U-SLOT PATCH ANTENNA WITH ENHANCED BANDWIDTH

In this paper, an asymmetric U-slot patch antenna with low probe diameter is presented. It will be shown that reduction in probe diameter causes in reduction in bandwidth. One of the characteristics of this antenna is keeping the bandwidth in 30% in spite of reduction in antenna size and use of low probe diameter compared to antenna presented in (1). The presented antenna in this paper has been fabricated by pcb technique and tested. The far-field results have also been presented based on simulation and measurement. Although the antenna has high cross polarisation level, in the case of using circular polarisation, the use of this antenna can be recommended because of its reduced size, high impedance bandwidth, high total gain in spite of having low size, and ease of fabrication.

Size Reduction of a Low-Profile Spiral Antenna Using Inductive and Dielectric Loading

This letter discusses a miniature low profile ultrawideband (UWB) spiral. The antenna is miniaturized using a combination of dielectric and inductive loading. In addition, a ferrite coated ground plane is adopted in place of the traditional metallic ground plane for profile reduction. Using full-wave simulations and measurements, it is shown that the miniaturized spiral can achieve similar performance to a traditional planar spiral twice its size.

Design and Development of a Novel Compact Soft-Surface Structure for the Front-to-Back Ratio Improvement and Size Reduction of a Microstrip Yagi Array Antenna

In this letter, a novel antenna structure based on a microstrip Yagi array antenna and a soft surface (SS) ring is proposed, that enables a highly directional gain in addition to an improved front-to-back (F/B) ratio of more than 20 dB. The SS ring is shown to be capable of greatly improving the performance while miniaturizing the design's size by half. The implementation of the SS ring to a microstrip Yagi array antenna is demonstrated to verify its functionality in suppressing surface waves, showing that an improvement of at least 3 dB in the F/B ratio can be obtained. The design is investigated at the center frequency of 5.8 GHz; however, the structure can be easily scaled to other frequency ranges. A design analysis is performed to give insight into the operational mechanism of the SS ring and the critical dimensions that affect the SS structure surrounding the antenna array. In addition, measurements are presented to validate the results obtained via simulation. The principles established in this letter can be applied to other planar antenna designs.

Disk-Loaded 다이폴과 Folded 다이폴로 동작하는 Reconfigurable 안테나

본 논문에서는 PIN 다이오드를 사용하여 disk-loaded 다이폴 안테나와 folded 다이폴 안테나로 형상이 변화하는 새로운 구조의 소형 안테나를 개발하였다. 개발된 안테나는 PIN 다이오드의 RF on/off 특성을 이용하여 안테나의 전기적 길이를 변화시켜 이중 대역에서 동작하며, 저주파 대역에서는 높은 복사 저항 값을 가지는 folded 다이폴 안테나로 동작하고 고주파 대역에서는 수평 방향으로 무지향성의 복사 패턴과 수직 방향으로 도넛 형태의 복사 패턴을 가지는 disk-loaded 다이폴 안테나로 동작한다. 제안된 안테나는 <TEX>$20{\sim}300$</TEX> MHz에서 30cm 다이폴 안테나에 비해 크기가 소형화 되었음에도 높은 이득을 가진다. 또한, <TEX>$300{\sim}1,300$</TEX> MHz에서 <TEX>$80^{\circ}$</TEX> 이상의 넓은 빔 폭을 가짐으로써 방향 탐지 안테나로 사용이 가능하다. In this paper, we propose a reconfigurable antenna which operates as a disk-loaded dipole antenna and a folded dipole antenna alternatively using RF on/off switches. The antenna can change its effective length to achieve dual-band operation; operates as the folded dipole antenna for stepping up the radiation resistance in low frequency band of <TEX>$20{\sim}300$</TEX> MHz, and as the disk-loaded dipole antenna for an omni-directional radiation pattern (horizontal plane) and a donut-shaped radiation pattern (vertical plane) in high frequency band of <TEX>$300{\sim}1.3$</TEX> GHz. In the low band, the proposed antenna shows higher gain than a conventional dipole antenna with a reduced antenna size. In the high band, the antenna maintains a broad beamwidth of about <TEX>$80^{\circ}$</TEX>, thus the antenna can be applicable to antennas for direction finding applications.

Reconfigurable Ground-Slotted Patch Antenna Using PIN Diode Switching

This letter presents a reconfigurable ground-slotted patch antenna using a PIN diode connection in slots to achieve dual-frequency operation. Slots in the ground plane increase the electrical length and thereby reduce antenna size by 53%. By controlling PIN diode conduction, we achieved band hopping while still satisfying the bandwidth requirements for K-PCS and WiBro bands.

Distributed Lumped Loads and Lossy Transmission Line Model for Wideband Spiral Antenna Miniaturization and Characterization

A lossy transmission-line model that incorporates the radiation resistance of small loop antennas is introduced to characterize the input impedance of a spiral antenna over a large frequency range. This model also leads to a concept of controlling the current velocity and impedance on a spiral antenna by introducing distributed reactive loading along the spiral arms. An important application of the concept is to reduce antenna size and this is demonstrated by numerical simulation examples.

Active integrated antenna for mobile TV signal reception

AbstractThis paper proposes a small‐sized field‐effect transistor (FET) based active integrated antenna (AIA) for terrestrial digital multimedia broadcasting (T‐DMB) signal reception, which is one of the mobile TV services allocated to 200 MHz band. The commercially used T‐DMB antenna is a 120 mm long monopole, but the size of the proposed one is reduced to 50 mm by the method of active device integration. The active device integrated to the radiator influences not only on the current distribution at the radiator but also the input impedance, results in an antenna size reduction with an enhanced gain. In addition to this, a band‐pass filter is designed at the input port of the radiator. This plays a role as a matching circuit between a radiator and an active device as well as provides a band‐selection function simultaneously to be free of other high intensity signals existing around the T‐DMB band. The antenna effective length related to the same‐sized monopole and noise figure are measured to verify the validity of the proposed antenna. The performance of the proposed FET based AIA shows the feasibility of designing absolutely small‐sized antenna with active devices integrated compared to an operating frequency band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2998–3001, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22968

Size reduction of microstrip patch antennas with left-handed transmission line loading

A procedure for designing an electrically small microstrip patch antenna (MPA) is developed, wherein the length of a side of the MPA is reduced to significantly less than a half-wavelength. The MPA is loaded with a resonant circuit equivalent to that of a left-handed transmission line to artificially increase the effective wavelength of the device, thus creating a resonance equivalent to, but at a lower frequency than the unloaded {10} mode. The field distribution in the loaded MPA remains relatively unperturbed, unlike the {0} mode case that attempts to decrease the size by introducing a shorting-post; consequently, very low cross-polarisation behaviour is observed. The theory to predict the full spectrum of resonant frequencies of the antenna is developed, with finite-difference time-domain simulations used to finalise the antenna design. Finally, an electrically small ((lambda/6)times(lambda/4)) and thin (<lambda/65) antenna is fabricated at 465 MHz using low-temperature co-fired ceramic technology and tested for key figures of merit, including the resonant frequency and radiation pattern. The shortened antenna not only shows performance comparable to a conventional unloaded MPA, but also exhibits good cross-polarisation. The loaded MPA achieved an area reduction of 83% as compared to an unloaded version

LOWPASS FILTER DESIGN OF HILBERT CURVE RING DEFECTED GROUND STRUCTURE

LOWPASSFILTERDESIGNOFHILBERTCURVERINGDEFECTEDGROUNDSTRUCTUREJ.Chen,Z.-B.Weng,Y.-C.Jiao,andF.-S.ZhangNational Key Laboratory of Antennas and Microwave TechnologyXidian UniversityXi’an 710071,ChinaAbstract—In this paper,a novel Hilbert curve ring (HCR) fractaldefected ground structure (DGS) and its equivalent circuit areinvestigated. Furthermore,an improved HCR DGS cell model withopen stubs loaded on the conductor line is then presented to improvethe out-band suppression. By employing three cascaded improvedHCR DGS cells,an L-band microstrip low-pass is designed andfabricated. This lowpass filter achieves a quite steep rejection property;a low in-band insertion loss of below 0.5dB and a high out-bandsuppression of more than 33dB.1. INTRODUCTIONRecently,there has been an increasing interest in the applicationsof defected ground structure (DGS) in microwave and millimeter-wave applications [1–3]. The DGS of the microstrip line employsan intentional defect on the ground and it provides band rejectioncharacteristic from the resonance property. The applications of theDGS are developed in divider,filter,and amplifier circuits. Thedefect of the conventional DGS is with the dumbbell shape or therectangle shape,these conventional DGSs,however,have a flat slopeof their rejection characteristic. To fabricate a lowpass filter with steeprejection property,many these DGSs are needed to be cascaded,whichalso means higher in-band insertion and larger size.Different from Euclidean geometries,fractal geometries have twocommon properties,space-filling and self-similarity. It has been shownthat the self-similarity property of fractal shapes can be successfullyapplied to the design of multi-band fractal antennas,such as theSierpinski gasket antenna [4],while the space-filling property of fractalscan be utilized to reduce antenna size [5,6].

Lutein is needed for efficient chlorophyll triplet quenching in the major LHCII antenna complex of higher plants and effective photoprotection in vivounder strong light

BackgroundLutein is the most abundant xanthophyll in the photosynthetic apparatus of higher plants. It binds to site L1 of all Lhc proteins, whose occupancy is indispensable for protein folding and quenching chlorophyll triplets. Thus, the lack of a visible phenotype in mutants lacking lutein has been surprising.ResultsWe have re-assessed the lut2.1 phenotypes through biochemical and spectroscopic methods. Lhc proteins from the lut2.1 mutant compensate the lack of lutein by binding violaxanthin in sites L1 and L2. This substitution reduces the capacity for regulatory mechanisms such as NPQ, reduces antenna size, induces the compensatory synthesis of Antheraxanthin + Zeaxanthin, and prevents the trimerization of LHCII complexes. In vitro reconstitution shows that the lack of lutein per se is sufficient to prevent trimerization. lut2.1 showed a reduced capacity for state I – state II transitions, a selective degradation of Lhcb1 and 2, and a higher level of photodamage in high light and/or low temperature, suggesting that violaxanthin cannot fully restore chlorophyll triplet quenching. In vitro photobleaching experiments and time-resolved spectroscopy of carotenoid triplet formation confirmed this hypothesis. The npq1lut2.1 double mutant, lacking both zeaxanthin and lutein, is highly susceptible to light stress.ConclusionLutein has the specific property of quenching harmful 3Chl* by binding at site L1 of the major LHCII complex and of other Lhc proteins of plants, thus preventing ROS formation. Substitution of lutein by violaxanthin decreases the efficiency of 3Chl* quenching and causes higher ROS yield. The phenotype of lut2.1 mutant in low light is weak only because rescuing mechanisms of photoprotection, namely zeaxanthin synthesis, compensate for the ROS production. We conclude that zeaxanthin is effective in photoprotection of plants lacking lutein due to the multiple effects of zeaxanthin in photoprotection, including ROS scavenging and direct quenching of Chl fluorescence by binding to the L2 allosteric site of Lhc proteins.

Size Reduction of Cavity-Backed Slot Antennas

A technique for reducing the dimensions of the cavity of a cavity-backed slot antenna (CBSA) is presented, which facilitates proper fabrication and integration of miniaturized slot antennas on multilayer substrates. This is accomplished by replacing the solid metal around the traditional slot antennas with a specific metallic pattern that can be viewed as a series of parallel strip lines placed around the slot antenna. This metallic pattern is then modified by designing the parallel strips in a compact fashion to reduce the overall antenna dimensions and obtain a reduced-size CBSA. It is shown that, for a simple straight slot antenna, the overall occupied volume of the modified cavity backing the slot antenna can be reduced by more than 65% without affecting the high radiation efficiency of the antenna. A number of traditional cavity backed slot antennas and the proposed modified CBSAs are designed, fabricated, and measured. The reduced-size CBSAs show a very low input VSWR, low cross-polarized radiation levels, and high radiation efficiency. Despite their small ground plane size, the proposed cavity backed slot antennas have front-to-back ratio (FTBR) values in the range of 6-7 dB

Design of a compact ultra-wideband antenna

A simple method for the design of ultra-wideband antennas in planar format is presented. This method is demonstrated for a high-dielectric-constant substrate material, which allows for a considerable antenna size reduction. Simulations are performed using Ansoft's High-Frequency Structure Simulator (HFSS) for antennas assuming DuPont951 (er = 7.8) and RT6010LM (er = 10.2) substrates. For the 1-mm-thick DuPont951, the designed antenna with 22 X 28 mm dimensions features a 10-dB return-loss bandwidth from 2.7 GHz to more than 15 GHz. For the 0.64-mm-thick RT6010LM a 20 X 26 mm antenna exhibits a 10-dB return loss bandwidth from 3.1 to 15 GHz. Both antennas feature nearly omnidirectional properties across the whole 10-dB return-loss bandwidth. The validity of the presented UWB antenna design strategy is confirmed by measurements performed on a prototype developed on RT6010LM substrate.

Advances in non-linear apodization

Selected new methods and applications of non-linear apodization for irre gula rly-shaped and parse coherent apertures and arrays are presented. The benefits include unproved impulse response performance, i.e., reduced peak sidelobes and integrated sidelobe power, along with impr oved mainlobe res olution, compared to classic windowing techniques. Non-linear apodization (NLA) techniques can also strve as powerful engines for effective superresolution and bandwidth extrapolation of coherent data for filling spars e apertures. The sparse aperture filling property of superresolution algorithms for radar data forms the basis for a new concept which is introd uced here: Synthetic Multiple Aperture Radar Technology (SMART). Increased swath and/or reduced antenna size are some of the benefits postu lated for SMART applied to synthetic aperture radar (SAR) systems. The benefits of the se new methods and applications for non-linear apodization are then demonstrated for two specific applications: 1) sidelobe control for Y -type synthetic aperture radiometers, such as the European Soil Moisture and Ocean Salinity (SMOS) system [12] and JPL's propos ed GeoSTAR [13] concept; and, 2) ftlling of spa rse synthetic apertur e radar data by exploiting the band width extrapolation properties of non-linear apodization based superresolution techniques. The methods that have been developed and demonstrated herein have potential application to a wide range of passive and active microwave remote sensing and radar systems.

Realization of a compact microstrip antenna: An optimization approach

A new compact square microstrip patch antenna is proposed using the optimization approach, namely, the genetic algorithm (GA). The antenna is designed at three different frequencies, 785 MHz., 1.57 GHz, and 2.46 GHz, for mobile communication, GPS, and Bluetooth applications, respectively. The simulations are carried out using IE3D from Zeland Software, which is based on the method of moments (MoM). The antenna consists of a probe-fed truncated-corner square patch with four inserted slits along the four diagonals and four angular grooves along the four edges of the patch. The proposed design has a reduced antenna size, as compared to the conventional microstrip antenna at a given operating frequency. The return loss, impedance, and axial-ratio bandwidth are determined and compared with the conventional square-patch antenna. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.

A Novel Analysis of Minkowski Fractal Microstrip Patch Antenna

Various techniques and geometries have been introduced for size reduction of Microstrip patch antennas, since this class of antennas in spite of inherent application deficiencies; possess preferred benefits in comparison with other choices. This paper presents an evaluation on a novel microstrip patch antenna using Minkowski fractal geometry. Simulation and experimental results indicate efficiency of this technique from the viewpoint of miniaturization for four designed patch antennas by four different depression coefficients. Simulation results are obtained using Ansoft HFSS.

A miniaturized antenna for 2G/3G frequency‐band applications

AbstractA novel miniaturized printed monopole antenna suitable for cellular handset terminals is presented. A substantial reduction in antenna size was achieved due to the use of the inverted‐F antenna concept combined with a capacitive feeding system. The antenna operates in three frequency bands, that is, GSM 1800, PCS 1900, and UMTS, with VSWR ≤2.5. The compactness of the antenna structure allows it to be placed on the top as well as the bottom of a handset. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 399–402, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21362