Planar Spiral Antenna Research Articles

Low-noise THz MgB2 Josephson mixer

The potential applications for high frequency operation of the Josephson effect in MgB2 include THz mixers, direct detectors, and digital circuits. Here we report on MgB2 weak links which exhibit the Josephson behavior up to almost 2 THz and using them for low-noise heterodyne detection of THz radiation. The devices are made from epitaxial film grown in the c-axis direction by the hybrid physical-chemical vapor deposition method. The current in the junctions travels parallel to the surface of the film, thus making possible a large contribution of the quasi-two-dimensional σ-gap in transport across the weak link. These devices are connected to a planar spiral antenna with a dielectric substrate lens to facilitate coupling to free-space radiation for use as a detector. The IcRn product of the junction is 5.25 mV, giving confirmation of a large gap parameter. The sensitivity of the mixer was measured from 0.6 THz to 1.9 THz. At a bath temperature of over 20 K, a mixer noise temperature less than 2000 K (DSB) was measured near 0.6 THz.

Temperature field simulation and phantom validation of a Two-armed Spiral Antenna for microwave thermotherapy.

In this paper, an Archimedean planar spiral antenna for the application of thermotherapy was designed. This type of antenna was chosen for its compact structure, flexible application and wide heating area. The temperature field generated by the use of this Two-armed Spiral Antenna in a muscle-equivalent phantom was simulated and subsequently validated by experimentation. First, the specific absorption rate (SAR) of the field was calculated using the Finite Element Method (FEM) by Ansoft's High Frequency Structure Simulation (HFSS). Then, the temperature elevation in the phantom was simulated by an explicit finite difference approximation of the bioheat equation (BHE). The temperature distribution was then validated by a phantom heating experiment. The results showed that this antenna had a good heating ability and a wide heating area. A comparison between the calculation and the measurement showed a fair agreement in the temperature elevation. The validated model could be applied for the analysis of electromagnetic-temperature distribution in phantoms during the process of antenna design or thermotherapy experimentation.

A planar equiangular spiral antenna with two annular rings

ABSTRACTThis article presents a novel antenna with an improved impedance bandwidth and axial ratio bandwidth. This new design is comprised of an equiangular spiral and two annular rings on the same plane. These are printed on a Taconic substrate with a dielectric constant of 2.2 and a thickness of 1.52 mm. The proposed antenna has good performance compared with the conventional equiangular spiral antenna. The simulation results are validated through experimental measurements, and the overall size of the spiral antenna is visibly reduced. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2865–2867, 2015

Optimal Design of RF Energy Harvesting Device Using Genetic Algorithm

This paper presents optimal design of an RF energy harvesting device using genetic algorithm (GA). In the present RF harvester, a planar spiral antenna (PSA) is loaded with matching and rectifying circuits. On the first stage of the optimal design, the shape parameters of PSA are optimized using $$\mu {\rm GA}$$ . Then, the equivalent circuit of the optimized PSA is derived for optimization of the circuits. Finally, the parameters of RF energy harvesting circuit are optimized to maximize the output power using GA. It is shown that the present optimization increases the output power by a factor of five. The manufactured energy harvester starts working when the input electric field is greater than 0.5 V/m.

Millimeter wave characteristics of intrinsic Josephson junctions with planar equiangular spiral antenna in misaligned Tl2Ba2CaCu2O8 thin film

An intrinsic Josephson junctions (IJJs) microbridge with planar equiangular spiral antenna (PESA) is proposed and studied by simulation and experiment. This IJJs circuit is simulated firstly to obtain the minimum of reflection coefficient and pattern. Secondly, IJJs with PESA are fabricated on misaligned Tl2Ba2CaCu2O8 superconducting film. The millimeter wave characteristics are investigated by a Febry–Pérot resonator, which consists of a spherical mirror antenna and a plane mirror. At 37.4GHz, the IJJs and the millimeter wave show an optimum coupling, which deviate from the simulation for only 0.004GHz. In addition, the extent of the coupling between IJJs and the resonator is discussed at different angle for the polarization direction of the spherical mirror antenna with the microbridge. The result shows that the strongest coupling is obtained at 0–30° angle. Good conformance of measurements and simulations illustrate the effectiveness of our design in strong coupling between sample and resonator.

Fabrication of a planar spiral antenna using direct writing technology

Radio frequency identification (RFID) is a non-contact automatic identification technology that allows transmission of information and power via radio frequency signals. It has advantages including a short recognition distance, favorable efficiency, and reliable security. Planar antennas are an important aspect of RFID tags, and are usually manufactured by winding, screen-printing, and etching methods. These production processes typically involve thermal/mechanical stresses, chemical corrosion and other manufacturing processes which restrict the choice of substrate. On the other hand, direct writing technology provides a number of advantages, including no restrictions on the substrate, reduced costs, and simplified manufacturing processes. Because of these advantages, we propose a fabrication process for a spiral antenna using direct writing technology of a conductive material. The direct writing system was developed using a dispensing system and a 3-axis stage system. Consequently, a planar spiral antenna for an NFC tag was fabricated. The inductance of the fabricated spiral antenna was in good agreement with the designed value.

Application of Gbest-guided artificial bee colony algorithm to passive UHF RFID tag design

In this paper, new planar spiral antennas with meander lines and loads for passive Radiofrequency identification tag application at ultra-high-frequency band are designed and optimized using the global best (gbest)-guided Artificial Bee Colony (GABC) algorithm. The GABC is an improved Artificial Bee Colony algorithm, which includes gbest solution information into the search equation to improve the exploitation. The optimization goals are antenna size minimization, gain maximization, and conjugate matching. The antenna dimensions were optimized and evaluated in conjunction with commercial software FEKO. GABC is compared with other popular algorithms. The optimization results produced show that GABC is a powerful optimization algorithm that can be efficiently applied to tag antenna design problems.

Shape Optimization of Wideband Antennas for Microwave Energy Harvesters Using FDTD

This paper presents parameter and topology optimizations of wideband antennas for microwave energy harvesters based on finite difference time-domain computations. The antenna shapes are optimized to reduce return losses in a specific frequency band using micro-genetic algorithm. The shape parameters of a two-arm planar spiral antenna are optimized. In addition, the topology optimization is performed using normalized Gaussian network, where spatial symmetries are assumed. It is shown that the return losses of the optimized antennas are <−10 dB from 1 to 2 GHz in which they have isotropic directivity.

CPW-fed compact UWB spiral antenna for multiband applications

A CPW-fed compact planar spiral antenna is presented. Different sections of the spiral monopole can excite multi resonant modes which makes the antenna suitable for multiband applications. The spiral is designed for dual band operation in GSM 1800 and UWB band. By using shorting strips between the arms of the spiral monopole, the frequency of the first operating band is lowered to WMTS band without change in overall antenna size. The antenna prototype is fabricated and tested. Simulated and measured readings are in good agreement. Radiation patterns are stable in all the intended bands of operation and group delay is nearly constant in the UWB range.

A Study on a Miniaturized Planar Spiral Antenna for Partial Discharge Detection in GIS

Ultra-high frequency (UHF) detection method can effectively detect the signals of partial dis- charge (PD) in electrical equipment. Hence the authors designed a sensor of miniaturized planar spiral antenna for detecting PD in gas insulated substations (GISs), which is sine-wave meandered based on the traditional Ar- chimedean spiral antenna in order to reduce the antenna's size. The test results indicate that this antenna has a wide-frequency band of 0.92~3GHz in terms of the voltage standing wave ratio (VSWR) which is smaller than 2. The antenna is smaller and its structure is simpler, its diameter is 97mm and its height is 51mm�◊ Besides, this antenna has an ultra-wideband, great directivity and the feature of omnidirectional radiation. Therefore, the pro- posed antenna is quite promising for PD on-line detection applications.

Low Noise Nanometer Scale Room-Temperature &lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;${\hbox{YBa}}_{2}{\hbox{Cu}}_{3}{\hbox{O}}_{7-x}$&lt;/tex&gt; &lt;/formula&gt; Bolometers for THz Direct Detection

We present a detailed investigation of the responsivity and the noise in room temperature THz direct detectors made of ${\hbox{YBa}}_{2}{\hbox{Cu}}_{3}{\hbox{O}}_{7-x}$ (YBCO) thin-film nano-bolometers. The YBCO nano-bolometers are integrated with planar spiral antennas covering a frequency range from 100 GHz to 2 THz. The detectors were characterized at 1.6 THz, 0.7 THz, 400 GHz and 100 GHz. The maximum electrical responsivity of 70 V/W and a minimum noise equivalent power (NEP) of ${\hbox{50}} {\hbox{pW/Hz}}^{0.5}$ were measured, whereas the highest optical responsivity was 45 V/W. The $(1/f)$ noise in nano-bolometers is independent on the device volume and can be found as $(V_{N}/V)^{2}=6\times 10^{-11}\times 1/f {\hbox{Hz}}^{-1}$ for a given modulation frequency $f$ and a dc voltage $V$ .

Design of load-ended spiral antennas for RFID UHF passive tags using improved artificial bee colony algorithm

In this paper, new planar spiral antennas for passive RFID tag application at UHF band are designed and optimized using a new artificial bee colony (ABC) algorithm. We apply the improved ABC (I-ABC), which is an improved version of the original ABC algorithm. The I-ABC introduces the best-so-far solution, inertia weight and acceleration coefficients to modify the search process. The optimization goals are antenna size minimization, gain maximization and conjugate matching. The antenna dimensions were optimized and evaluated using I-ABC in conjunction with commercial EM software. We compare the I-ABC with the original ABC algorithm. The obtained results show that both algorithms are powerful optimizers that can be efficiently applied to tag antenna design problems. I-ABC produces better results than the original ABC algorithm in terms of solution accuracy and success rate. RFID tags with dimensions less than 3cm, maximum gain that reaches the value of 1.46dBi and read distance more than 10m were among those obtained by the algorithm.

Polarization states imaging of electromagnetic wave

An experimental technique for visualizing in-plane distributions of polarization states for an electromagnetic wave has been proposed and demonstrated successfully; distributions of rotating electric near-field vectors Exy as well as their elliptic traces have been imaged electrooptically at a series of distances from the surface of a side-fed planar spiral antenna. The visualization was brought about by merging Ex and Ey phasor videos acquired complementarily by the live electrooptic imaging technique.

Transmission line analysis of the Archimedean spiral antenna in free space

This paper examines the transmission line structure of a planar Archimedean spiral antenna. A novel analysis is performed by unwinding the spiral into an equivalent straight transmission line to understand its impedance properties and the radiating mechanism. A relation between the input impedance of the spiral antenna and the characteristic impedance of our proposed model is established. The analytical solution completes the lossy transmission line modelling for the input impedance of the spiral antenna. The value of the stable input resistance in the spiral’s radiation region is found not due to the radiation resistance of the loop antenna, but it is dominated by the propagation characteristics of the slot-line mode, that is the travelling wave on the spiral. The accuracy of this proposed model is verified by full-wave simulations, the Babinet’s principle, and measurements. Examination of the radiation mechanism and discussion on the effects of other parameters such as feeding design are also provided.

FAR-FIELD SYMMETRY ANALYSIS AND IMPROVEMENT OF THE CAVITY BACKED PLANAR SPIRAL ANTENNA

The far-fleld pattern symmetry of the cavity backed planar spiral antenna is analyzed. We discover that the back radiation of the planar spiral and the cavity efiects degrade the pattern symmetry. To improve the pattern symmetry, an improved method to reduce the back radiation is proposed. Then a novel antenna conflguration is designed. The center section of the planar spiral is replaced with a conical spiral. So the back radiation at higher frequency band can be restrained. The broadside gain, axial ratio and pattern symmetry are compared. The results show that this novel conflguration can achieve better far-fleld symmetry at a wider band.

Novel Spiral Antenna Design Using Artificial Bee Colony Optimization for UHF RFID Applications

In this letter, a new planar spiral antenna for passive radio frequency identification (RFID) tag application at UHF band is designed and optimized using the Artificial Bee Colony (ABC) algorithm. The optimization goals are antenna size minimization, gain maximization, conjugate matching, and in consequence the maximization of the read range. The antenna dimensions were optimized and evaluated using ABC in conjunction with commercial electromagnetic (EM) software. The comparison of the results obtained by ABC to respective ones of other popular evolutionary algorithms show that ABC can be efficiently applied to tag antenna design problems. To validate the theoretical results, designed RFID tags were fabricated, and their reading efficiency was evaluated experimentally. The results of simulation and those received via measurements prove that the proposed method for the design of passive RFID tag antennas is efficient, as antennas with dimensions less than 3 cm, gain that reaches the value of 1.6 dBi, and read range about 6 m were obtained.

A Rectangular Planar Spiral Antenna for GIS Partial Discharge Detection

A rectangular planar spiral antenna sensor was designed for detecting the partial discharge in gas insulation substations (GIS). It can expediently receive electromagnetic waves leaked from basin-type insulators and can effectively suppress low frequency electromagnetic interference from the surrounding environment. Certain effective techniques such as rectangular spiral structure, bow-tie loading, and back cavity structure optimization during the antenna design process can miniaturize antenna size and optimize voltage standing wave ratio (VSWR) characteristics. Model calculation and experimental data measured in the laboratory show that the antenna possesses a good radiating performance and a multiband property when working in the ultrahigh frequency (UHF) band. A comparative study between characteristics of the designed antenna and the existing quasi-TEM horn antenna was made. Based on the GIS defect simulation equipment in the laboratory, partial discharge signals were detected by the designed antenna, the available quasi-TEM horn antenna, and the microstrip patch antenna, and the measurement results were compared.

A compact broadband spiral antenna for millimeter wave applications

ABSTRACTThe planar spiral antenna being connected with the waveguide and operating in the long‐wave region of the millimeter range is proposed. The antenna has the bandwidth of 6 GHz and the axial ration which does not exceed −3dB in the frequency band 32–36.5 GHz. The radiation pattern shape is slightly changed within the operational frequency band. The results of simulations and experimental data are in good agreement. The nature of radiation pattern and axial ration changing within the operational frequency band is explained from the analysis of near‐field distributions measured at two orthogonal polarizations. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:293–297, 2014

Design of Broadband Planar Spiral Antenna for Partial Discharge in Cable

The detection of partial discharge in power cables is an effective method to diagnosis early fault of XLPE cable . When partial discharge occurs, it emits abundant frequency component in ultra-high frequency (UHF) band, and broadband planar spiral antenna is an effective sensor to detect UHF partial discharge signals. High frequency electromagnetic simulation software Ansoft HFSS is used to simulate and analysis planar Equiangular spiral antenna and Archimedean spiral antenna. The simulation results show that the two kinds of antennas work effectively in 400 MHZ ~ 1 GHZ frequency band and are high sensitivity and superior performance. Because of with smaller size and larger gain, the Archimedean spiral antenna is used to detect UHF signals of partial discharge in XLPE cable.

Electric Micro-Propulsion in Low Temperature Co-fired Ceramics

This work focuses on the fabrication and assembly of miniature inductively-coupled plasma (ICP) electrostatic thrusters using DuPont's 951 Low Temperature Co-Fired Ceramics (LTCC). The use of LTCC allows for integration of electrical and fluidic features inside a hermetically sealed device that is resistant to plasma erosion. LTCC also allowed for the creation of cylindrical and planar structures which could be mated to form a single device. The thruster consists of a planar base, an antenna disc, and a plasma containment cylinder. The planar base contains internal fluid distribution channels as well as electrical interconnections. The antenna disc houses straight-through gas ports, electrical interconnects, as well as a planar spiral ICP antenna. The containment cylinder is used to contain argon plasma created by a radio frequency (RF) signal sent through the ICP antenna. The development of the fabrication process will be presented for the incorporation and alignment of all three LTCC components together to create a single thruster body. The results of the electrical and fluidic integration of the device will be evaluated and presented.