Search

This work describes the design, fabrication, and testing of an Archimedean spiral or spiral antenna using polymer extrusion 3D printing of polycarbonate base material. The spiral antenna design was simulated using CST Microwave Studio (R), and the resulting 3D printed antenna characterized in terms of return loss, directivity, and polarization. The antenna design was embedded into a 3D printed structure using a unique ultrasonic method while a ground plane was inserted through a thermal embedding process. These fabrication methods provide process flexibility, which allows multiple conductive antenna layers to be additively constructed in a single build sequence. The method described can be used to create unique electromagnetic structures such as waveguides directly in a 3D printed dielectric part. The spiral antenna was tested with three variations of microstrip feed line used to match 50 impedance and introduce a 180 degrees phase shift between the two arms of the spiral. These include a Duroid balun attached to feed of the antenna after fabrication, a Duroid balun embedded into the polycarbonate during fabrication, and the same microstrip design fabricated out of copper mesh and embedded into the structure using the polycarbonate as a dielectric substrate. The results of these three approaches will be discussed. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1662-1666, 2016

This paper reports the investigation on a new spiral antenna constructed using well-known Fibonacci sequence. Its performance has been compared first with a universal logarithmic spiral antenna (LSA) of nearly the same dimension. Next the discontinuous geometry of the proposed Fibonacci spiral antenna (FSA) has been exploited to fractalize it using Koch curve. The fractalized Koch-FSA has nearly two-third of physical size miniaturization while retaining antenna radiation characteristics.However like other spiral antennas, the multiband behavior of FSA is evident because of conducting ground plane just below it. The geometries of the antenna have been simulated using CST Microwave studio and fabricated over lossy FR-4 substrate with dielectric constant er = 4.33, loss tangent tanδ = 0.0025 and thickness, ts = 1.5 mm. The measured results are in well agreement with simulations. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1315–1319, 2016

For avoiding a dead zone where the tag cannot be detected in the ultrahigh-frequency (UHF) radio frequency identification (RFID), a SELECTABLE SECTORAL ANTENNA ARRAY USING a QUADRUPLE FEEDING NETWORK FOR ITEM-LEVEL TAGGING IN UHF RFID APPLICATIONS is presented. The proposed antenna array consists of a 2 × 2 circular polarized quadrifilar spiral antenna array and a quadruple feeding network for multiple beams. It generates single, dual, and quad beams with a hemispheric coverage by a beam switching, and its maximum gain and 3 dB beamwidth are approximately 7.8 dBic and 60°, respectively. Compared with the conventional antennas, the proposed antenna array provides the improved tag identification with the dead zone avoidance in the reading range. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1523–1526, 2015

Effects of lossless cavity-backing on time-domain performance of a two-arm combined equiangular/power spiral antenna are discussed. The impact of cavity depth is studied and guidelines for achieving low pulse distortion are established. The resistive arms' termination is found to be necessary to achieve a compromise between good time and frequency performances at the expense of efficiency at low frequencies. Developed antenna with diameter to depth ratio of 8:1 has wide-angle fidelity factor of 90% while maintaining VSWR 5 dBic, and axial ratio

A right-hand circularly polarized beam steering spiral antenna is presented in this article. It is designed using the standard p-i-n technology, enhanced with arm switches and biasing lines. The ensuing design is easily manufactured and is functionally competitive with the more complex ones, based on RF-MEMS. Three beams, tilted 40° with respect to the spiral central axis, are generated at 3.3 GHz, suitable for WiMax systems at this frequency. These beams are directed at approximately 90°, 180°, and 270° in the azimuth space. Beam directions depend on various configurations of the seven p-i-n diodes added to the spiral structure. The states of the diodes are subjected to the two DC bias voltages connected to the spiral arm. The radiation performance over the 200-MHz bandwidth (3.2–3.4 GHz) is relatively stable. Measurements in this band show the reflection coefficient below −10 dB and the axial ratio below or close to 3 dB at the peak beam directions. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1636–1640, 2014

A new spiral patch microstrip antenna frequency independent, able to generate a range of frequencies for the transmission and reception of ultrawideband signals, is presented. This antenna operates perfectly with frequencies above 2 GHz without the need for adjustments in its parameters. Measured results have been compared with simulated results and found to be in a good agreement. The spiral antenna produces a remarkable bandwidth to VSWR 2:1. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:861–864, 2014

The 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

This 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

A new planar spiral antenna with integrated impedance transformer is presented which needs no external balun and can be fed by a coplanar waveguide.The proposed structure has a return loss of

The ultrawide-band antenna with original transformer providing the required electromagnetic matching of the coaxial cable with the small-size single-arm equiangular spiral antenna is proposed. The measured input reflection coefficient of the small-size spiral antenna is less than −10 dB within the frequency band from 7.5 to 40 GHz. The near-fields, radiation patterns and axial ration within the impedance antenna bandwidth are presented and discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2190–2194, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27018

Performance of an offset-fed curl antenna over artificial magnetic conductor (AMC) ground planes is investigated.An extensive parametric study is carried out and shown that by proper selection of the AMC ground plane and spiral parameters, a moderate axial ratio and wide impedance bandwidths can be obtained. The performance results for a design example are provided and discussed. The effect of the air gap between the AMC and antenna substrates is also studied and shown that the operating frequency moves to higher frequencies. The results are verified by experiment. The simulation studies were carried out using the finite element software HFSS v10.1. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1036–1041, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25929

In this article, a new antenna is introduced for ingestible capsule endoscope systems. As capsule endoscope systems are supposed to operate in the human body and they transmit internal image data with high resolution to external receivers, a wideband small antenna is required. To obtain these properties, the proposed antenna is designed in the form of thick-arm spiral structure. The total height of the antenna is 5 mm and the diameter is 10 mm. The fractional bandwidth of the proposed antenna is 21% with VSWR < 2, which is wide enough for WBAN in body communication and it has the isotropic radiation pattern. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:529–532, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25808

A novel quadrifilar spiral antenna is proposed for use in personal communications mobile terminals exploiting the “big low earth orbit” (big-LEO) satellite system (uplink 1.61–1.63 GHz; downlink 2.48–2.5 GHz). Feeding of the antenna from the outer periphery is proposed, to avoid the complexity and space requirements of a centre feed; an externally fed antenna can also be fed either by coaxial cables or stripline. Moreover, the hybrid phasing network and the matching network (if required) can be located outside and possibly printed in the same plane as the antenna structure. Versions of the design were investigated using the method of moments and in hardware realizations. These had a finite ground plane with air dielectric between the spirals and the ground plane. Performance suitable for satellite mobile system applications was demonstrated, including dual-band matching. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:987–990, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25090

A two arm Archimedean spiral antenna is modified to form various slow wave structures that have much lower operating frequency than the conventional spirals, making them compact elements for wideband array applications. Uni-directional patterns are obtained from a slow wave modified circular star spiral with electromagnetic band gap (EBG) structure. Measured return loss of circular star spiral at 2 GHz backed by perfect electric conductor at λ/4 is −16.37 dB and this is improved to −20.25 dB when the antenna is placed over an EBG at a separation of λ/10. The radiation pattern of antenna on EBG provides a back lobe suppression of 30 dB over an isolated planar modified spiral antenna. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1270–1274, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24303

The air bridged RF-MEMS capacitive series switches in single pole single throw transmission lines for reconfigurable antenna applications are presented. The RF characteristics of capacitive series switches are analyzed, measured, and compared with microstripline and coplanar-waveguide, which are generally used for transmission lines of MEMS reconfigurable circuits. RF-MEMS series switches are fabricated in both transmission lines on a glass substrate (er = 7.4 and tan δ = 0.001). The reconfigurable beam steering spiral antenna (fo = 11 GHz), which is monolithic integrated with RF-MEMS capacitive series switches on the same glass substrate, is also presented as an example of the use of in-line capacitive series switches. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 3130–3134, 2007; Published online in Wiley Inter-Science (www.interscience.wiley.com). DOI 10.1002/mop.22971

A spiral antenna with a helix loaded is investigated in this paper. Through combining the spiral with a helix together, circular polarization can be achieved in dual bands. Since the helix is loaded in the lower part of the spiral, this technique doesn't increase the antenna's volume but at the same time introduces another CP band. The experimental result shows that the lower band and upper band are 4.0% and 62.07% respectively. The characteristics of impedance, current distribution and radiation pattern will also be presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1939–1942, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22596

This paper describes a compact, self-complementary square-spiral antenna on a GaAs substrate with a broadside high-directivity (∼29 dB) frequency-independent pattern when coupled through a silicon hyperhemisphere. The driving-point resistance undulates between ∼100 and 300Ω from 200 GHz to 1 THz—much higher than the 72Ω value from Booker's modified formula, but quite beneficial for coupling to high-impedance broadband devices. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 524–529, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21398

Based on a planar inverted-F antenna (PIFA) configuration, two different shaped (meandered and spiral) antennas are designed using finite-difference time-domain (FDTD) simulations and measurement results. The antennas are installed on an implantable medical device in a biological-tissue simulating model. The impedance-matching and radiation characteristics of two PIFAs are compared in order to observe which shape is more appropriate for wireless communication links of implantable medical devices. Additionally, the effects of the human skin's thickness on the antennas are studied in order to consider medical devices which are implanted in various subcutaneous tissues. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 567–572, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21409

A patch array is tested as reflector. The reflection coefficient for a plane wave is measured, the findings are explained by the functioning of a single patch. A λ/2 dipole and a 2-arm spiral antenna are fitted with this reflector. It enhances the gain with the complete structure remaining small. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 172–175, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10548

A broadband antenna designed to radiate high directive circularly polarized radiations is presented. This design utilizes spiral arms to achieve a broad frequency bandwidth and radiates circularly polarized fields. To enhance the directivity, the spiral arms are axially elevated to have a radiation beamwidth narrower than that radiated from an analogous spiral antenna in the upward direction. This antenna is suitable for many microwave applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 303–305, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24040

This article introduces a miniaturized compound spiral slot antenna with a wideband balun and a back cavity. The simulated and experimental results show that the proposed antenna presents good circular polarization and wideband properties. Its measured return loss is less than −10 dB in the frequency range 0.75 to 8 GHz (10.7:1) and the axial ratio is less than 3.5 dB in the range 0.95 to 8 GHz. Comparing with the conventional spiral antenna, the proposed antenna diameter is only one fourth of that of the former, therefore the antenna size is significantly reduced. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2799–2801, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23801

A new type of artifical metallic electromagnetic structure, high impedance electromagnetic surface (HIS), has been developed that is characterized by having high surface impedance. In this paper, the HIS is used as the antenna ground plane to suppress the propagation of surface waves and improve performance of Archimedean planner spiral antenna. Measured results reveal that the HIS can remarkably increase the gain of main lobe, decrease the back lobe, and reduce the mutual coupling between receiving antenna and transmitting antenna. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 129–131, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22097

A dual spiral-loop strip antenna fed by coplanar stripline (CPS) is proposed and developed for circularly polarized printed antennas with miniaturized size and broad bandwidth. The overall size is reduced in circumference by about 33%. A printed feeding circuit is designed and implemented using uniplanar CPS technology in order to realize good impedance matching. The predicted results are validated by the experiment. The measured bandwidths under a 3-dB axial ratio and voltage standing-wave ratio are found to about 10% and 6%, respectively. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 506–508, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21030

This paper presents a two-arm microstrip spiral antenna with a circular aperture on the ground plane that produces either an axial beam or a tilted beam, depending on the operating frequency. A 50-Ω microstrip feedline is divided into two 100-Ω lines that feed the spiral antenna from the outer end of the spiral arms with a 180° phase difference at fo. The antenna is realized on a planar form without any balun circuit using a microstrip structure, which is easily compatible with millimeter- and microwave-integrated circuits. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 453–455, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10636

A low-profile offset-fed spiral antenna over an artificial magnetic conductors (AMC) ground plane is studied in which the AMC ground plane has a two-layer structure with an air-gap present between the layers.The effect of such air gaps on the axial ratios of the antenna is investigated. The predicted numerical results are verified by testing a prototype sample of the proposed antenna showing a satisfactorily agreement between them. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2422–2423, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26248