Quadrifilar Helical Antenna Research Articles

A compact channel patch antenna with reconfigurable circularly polarized pattern for mobile satellite communications

A compact dual-band circularly polarized antenna with a characteristic of pattern reconfiguration is proposed for S-band satellite handsets. The antenna works as a patch antenna in a channel shape with no ground beneath reaching an overall size of 0.55λ × 0.14λ × 0.1λ. The dual-band performance is realized through multi-branch slots of the patch. The antenna mainly consists of a channel metal patch, a channel dielectric, and a simple feeding network. The overall shape of slot can be changed by the PIN diode on the patch to adjust the surface current direction, which in turn achieves 180° switching of the left-hand circularly polarized radiation beam direction. In addition, by combining the quadrifilar helical antenna, which is switchable in the end-fire beam direction, the designed antenna can realize the switching of four main beam directions to achieve 360° 3D spatial coverage. The proposed antenna is fabricated and measured to verify the proposed design. The test results show that the designed antenna obtains circularly polarized radiating characteristics in S-band with the center frequency of 1.98 GHz and 2.2 GHz, and the test results and simulation results are basically consistent, which indicates the superior performance of the designed antenna.

S-Band Transceiver Antenna for Telemetry and Telecommand Applications

In this article, a novel compact, single-fed circularly polarized transceiver patch antenna is designed and developed for Telemetry, Tracking, and Command (TT&C) applications. Conventionally two distinct antennas are required for TT&C functionality, but the proposed solitary patch antenna accomplishes both tasks by reducing power, cost, antenna weight, and placement complexity. Since TT&C requires isotropic coverage, a Quadrifilar Helical antenna is placed on the earth-facing side, while the proposed antenna is mounted on the non-earth facing side and serves as a null filling antenna for the microsatellite developed by the PES University. The antenna consists of a diagonally fed radiating patch with two circular radiators stacked on top of each other with spacers to achieve 13.5% wider bandwidth for uplink (2.025-2.11 GHz) and downlink (2.2-2.29 GHz) applications. The simulated result shows that the antenna achieves a good impedance matching and axial ratio by covering a wide impedance bandwidth of 370 MHz, a wide beamwidth of 120° and cross-polarization isolation of 15dB. The antenna is fabricated using space-qualified material and tested along with the satellite structure at DARE, DRDO, Bangalore. It is also robust and can withstand thermal shock and vibration. Experimental validation shows that the simulated results agree well with the measured results.

Dual-Band Spiral Printed Quadrifilar Helical Antenna Miniaturized by Surface and Inner Dielectric Loading

The design and implementation of a spiral-folded printed quadrifilar helical antenna (FPQHA) is presented for a global positioning system (GPS) $L1$ -/ $L2$ -band application. The proposed FPQHA can be miniaturized by inserting dielectric loading inside the helix, covering the radiation elements by the dielectric sealant and turning the radiation elements into the form of parallelogram spirals. The manufactured antenna’s radiation elements are printed on a hollow rod ceramic substrate with a diameter of 12 mm and a height of 24.7 mm. The measurement results of the proposed FPQHA mounting on unmanned platform fit very well with the simulations, which validates the design methods and suggests that the proposed FPQHA is suitable for GPS $L1$ -/ $L2$ -band applications.

Design and analysis of Quadrifilar helical antenna for Cube-Sats using C-band frequency range for satellite communication

Design and analysis of Quadrifilar helical antenna are presented in this paper. The proposed antenna is designed for Cube-Sats in the low earth and medium earth orbits. It is a combination of four helical antennas, each separated by 90?, and excited separately at the feeding point. The antenna is designed for operation at 4.5 GHz with an impedance bandwidth of 11.11 %. Design of the antenna is done in two steps. The first step being the design of a ground plane, which can make the antenna operate at 4.5 GHz. The second step is to analyze the antenna?s performance for different helix angles using the best ground plane dimensions obtained in the first step. The gain versus frequency curve has been obtained and the designed antenna is having a gain of more than 4 dB at the resonant frequency of 4.5 GHz.

Printed quadrifilar square‐helical antennas with folded arms for satellite applications

In this study, a new straightforward method for construction of the printed quadrifilar helical antennas is presented. Folded helices with square shapes are used as the arms of the proposed antenna for satellite applications. The proposed structure is consisting of four printed flat walls with similar patterns of arms on each wall. Patterns of the folded arms are printed on four flat substrates with removed ground layers and the antenna structure is obtained by connecting these substrates. Two versions of the proposed antennas are designed for operating at 435 MHz with isolated and connected arms. Both antennas have minor responses at 145 MHz; however the large antenna with connected arms has better results. In addition, the large antenna has wider bandwidth and higher gain at both operating frequencies. Furthermore, the proposed antenna can be used as a wideband antenna with 34% bandwidth.

Polarization and Pattern Reconfigurable Cuboid Quadrifilar Helical Antenna

A novel cuboid quadrifilar helical antenna (QHA) with polarization and pattern reconfigurabilities is presented. The proposed antenna consists of a reconfigurable radiator and a switchable feeding network. The radiator combines two individual QHAs in a cuboid, which can be alternatively activated. The feeding network provides switchable quadrature excitations to the radiator. By controlling the p-i-n diodes on the radiator and the feeding network, four working states including both polarization and pattern agilities are achieved. The polarization of the antenna can be switched between two orthogonal circular polarizations, and the radiation pattern can be changed between broadside and backfire modes. A prototype designed to operate at 0.9 GHz band is developed and measured. The measured results validated that the antenna achieved the four working states with stable wide-beam radiation patterns. Moreover, the proposed antenna obtained wide impedance and axial-ratio bandwidths (36.2% and 22%, respectively) in a compact size ( $0.26\lambda _{0}\times 0.26\lambda _{0}\times 0.25\lambda _{0}$ ). The proposed antenna which has attractive electrical characteristics can be applied to various wireless communications, e.g., RFID readers, subway, and railway communications.

Steerable miniaturised printed quadrifilar helical array antenna using digital phase shifters for BGAN/GPS applications

A novel electronically steerable phased array antenna is developed for global positioning system/broadband global area network (GPS/BGAN) navigation applications. The array is composed of 2 × 2 printed quadrifilar helical antennas (PQHAs) integrated with digital phase shifters for beam steering over the transmit/receive bands. The feed network of each PQHA is based on a sequential rotation to achieve wideband circular polarisation (CP). An elegant control network with the embedded microcontroller is designed to provide driving bits to the phase shifters with reduced phase error. The meandered line design maintains high-performance CP radiation up to ±60° off-axis, within 1525 to 1660 MHz, and its size is 44% of the design with straight lines. The array gain is positive over 1450-1800 MHz beyond the BGAN band, with better than 13 dB return loss and <;2.2 dB axial ratio. The measured broadside gain of the array exceeds 8.5 dBi at 1600 MHz, and has a wide beam steering of ~±80° over the BGAN band. The developed antenna represents a significant technical advance to the design and manufacturing of PQHA array, it has a compact size, low cost and lightweight with a relatively large bandwidth and almost hemispherical coverage with excellent right-hand circularly polarized radiation.

Quarter‐wavelength printed quadrifilar helical antenna design for UHF RFID handheld reader applications

AbstractThis article presents a compact size and light weight PQHA for handheld UHF RFID reader applications. Quarter‐wavelength inverted‐F resonators are employed as the basic radiation elements for the four arms of the QHA. The height of the designed reader antenna is only 27 mm so that it features compact size but still preserves satisfactory electrical performance. The antenna is fed by a four‐port quadrature phase feeding system fabricated by only lumped elements. The feeding system printed on a FR4 substrate measures only 60 × 60 × 1.6 mm3. The measured fractional bandwidth of the proposed PQHA system is about 21% and the 3‐dB axial ratio bandwidth ranging from 800 to 1000 MHz covers the whole UHF RFID band. The measured maximum gain is around 3.2 dBic in the North American band and the 3‐dB beamwidth is about 120° at 920 MHz. The measured reading distance along line of sight is approximately 7.2 m using a commercial 4W EIRP reader and a standard tag. The advantages of the antenna are easy implementation, light weight and low cost, making it suitable for handheld UHF RFID reader applications.

A Design of an Origami Reconfigurable QHA with a Foldable Reflector [Antenna Applications Corner

This article presents a design of an origami reconfigurable circularly polarized quadrifilar helical antenna (QHA) with a foldable reflector that can operate in K, Ka, and extremely high-frequency (EHF) bands. A 10:1 scale prototype of the proposed antenna is built and validated through measurements and simulations.

A Study on the Control of BDS/GPS Self-phase Quadrifilar Helical Antenna for Ship

A Study on the Control of BDS/GPS Self-phase Quadrifilar Helical Antenna for Ship

Design of novel multiband folded printed quadrifilar helical antenna for GPS/WLAN applications

A tunable multiband folded printed quadrifilar helical antenna (FPQHA) is proposed. Creating slot on the arms of FPQHA is a simple approach for designing multiband helical antenna. Also varying width and length of the slot can cause to tune the interested frequency bands. The operating frequency ranges in L/S/C band that covers L1 GPS band and most of the commercial wireless communication systems, such as WLAN [IEEE 802.11 (2.4/3.6/5 GHz)], LTE and WiMAX (2.5/3.5 GHz).

Subject‐loaded quadrifilar helical‐antenna RF coil with high B1+ field uniformity and large FOV for 3‐T MRI

AbstractA novel method for excitation of RF B1 field in high‐field (3‐T) magnetic resonance imaging (MRI) systems using a subject‐loaded quadrifilar helical antenna as an RF coil is proposed, evaluated, and demonstrated. Design, analysis, characterization, and evaluation of the novel coil when situated in a 3‐T MRI bore and loaded with different phantoms are performed and cross‐validated by extensive numerical simulations using multiple computational electromagnetics techniques. The results for the quadrifilar helical‐antenna RF body coil show (a) strong field penetration in the entire phantoms; (b) excellent right‐hand circular polarization (RCP); (c) high spatial uniformity of RCP RF magnetic field, B1+, throughout the phantoms; (d) large field of view (FOV); (e) good transmit efficiency; and (f) low local specific absorption rate (SAR). The examples show that the new RF coil provides substantially better B1+‐field uniformity and much larger FOV than any of the previously reported numerical and experimental results for the existing RF coil designs at 3 T in literature that enable comparison. In addition, helical RF body coils of different lengths can, for instance, easily provide an excellent RCP and highly uniform B1+‐field within the MRI maximum FOV length of 50 cm, and even 100 cm. The proposed MRI RF coil yields a remarkable improvement in the field uniformity in the longitudinal direction, for various phantoms, with comparable efficiency and SAR levels.

A three-dimensional circularly polarized antenna with a low profile and a wide 3-dB beamwidth

An improved three-dimensional circularly polarized quadrifilar helix antenna (QHA) with low profile and wide 3-dB beamwidth is proposed and its performance is investigated both numerically and experimentally. The proposed modified QHA is comprised of a short-circuited quadrifilar helical antenna printed on a thin FR4 substrate, with its four ports terminated by 50 Ω resistances. In addition, four monopoles with 90° phase progression are positioned around the quadrifilar helical antenna, and four Archimedean spirals are used to top-load the monopoles. Simulated and measured results show that the proposed antenna achieves a bandwidth of 23.8%, has a 3-dB beamwidth greater than 170°, and its axial ratio is less than three in the entire upper hemisphere over a wide frequency band.

Multi-band conical and inverted conical printed quadrifilar helical antennas with compact feed networks

Comparison between radiation patterns of quadrifilar helical antennas with three shapes of cylindrical, conical and inverted conical is provided in this paper. Multi-folded printed lines are used as the arms of quadrifilar helical antennas and the heights of them with their supports are fixed at 35cm to make a valid comparison. These antennas have multiple resonance frequencies and they can be used for multiband applications. Radiation patterns of the three shapes are compared at three resonance frequencies, 435MHz, 620MHz and 755MHz. It is indicated that the conical antenna has a wider beam-width and the inverted conical antenna has higher gain at broadside. In addition, three compact feed networks based on miniaturized single layer Wilkinson power dividers for three frequency bands of the antennas are designed and their parameters are reported. Furthermore, the conical antenna and the feed networks are fabricated and simulation results are validated by the measurement results.

Miniaturisation of quadrifilar helical antenna: impact on efficiency and phase centre position

This study addresses the intrinsic limitations of the miniaturisation of very-high frequency-band quadrifilar helical antennas. Several designs with a relative size (i.e. the ratio between antenna's heights after and before the miniaturisation) down to 27% are obtained using an optimisation process based on intensive full-wave electromagnetic simulations. Reported simulation and experimental results underline the impact of height reduction on the antennas main descriptors: radiation pattern, directivity, polarisation purity, input matching, efficiency and maximum achievable gain. It was observed that the efficiency and the gain do not decrease linearly with the reduction of the antenna height and the input matching is slightly improved for the compact antennas. The shape of radiation pattern and the polarisation purity are not significantly degraded for relative size down to 27%.

Octafilar Helical Antenna for Portable UHF-RFID Reader

Octafilar helical antenna (OFHA) is proposed for handheld ultra-high-frequency (UHF) radio frequency identification (RFID) reader. The investigated antenna configuration consists of OFHA placed on reader device in the presence of human hand model. The antenna is designed at UHF band centered at 915 MHz. The antenna return loss, axial ratio, gain, co-polarized and cross-polarized field components are calculated using the finite element method (FEM) and compared with that calculated by finite integration technique (FIT) for verification of the simulated results. A comparison between the performance of the quadrifilar helical antenna (QFHA) and the octafiliar helical antenna (OFHA) designed at 915 MHz in the presence of the reader device and human hand model is investigated. The OFHA introduces high gain, high front to back ratio, good axial ratio and omnidirectional coverage.

Size Reduced Multi-Band Printed Quadrifilar Helical Antenna

A simple and innovative method for designing a spiral folded printed quadrifilar helix antenna (S-FPQHA) for dual-band operations is presented. The axial length of a conventional PQHA is miniaturized of about 43% by meandering and turning the helix arms into the form of square spirals. Parametric studies are performed to explore the performance improvements. Based on the studies a dual band antenna working in L1/L5 GPS application is realized with a good gain and a good circular polarization. Measured results are presented to validate the concept.

Design of a Printed Quadrifilar-Helical Antenna on a Dielectric Cylinder by Means of a Genetic Algorithm [Antenna Applications Corner

This paper presents the application of a genetic algorithm (GA) to the optimization of an S-band quadrifilar-helical antenna, which is printed on a dielectric cylinder. This antenna was designed for LEO satellite applications. Its saddle-shaped pattern should compensate for free-space loss variations in the satellite's footprint. The steady-state genetic algorithm was used for this optimization and an elitist strategy was implemented. The selection strategy in the present genetic algorithm was proportionate selection.

Compact Printed Quadrifilar Helical Antenna With Iso-Flux-Shaped Pattern and High Cross-Polarization Discrimination

In this letter, a technique for the miniaturization of conventional printed quadrifilar helical antennas using simple sinusoidal profiles is described and supported by experimental results. The challenge is to reduce the size of the antenna while maintaining iso-flux radiation patterns and high cross-polarization discrimination. The miniaturization design approach simulation and measurement results are given in the case of a specific design of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> -band telemetry link antenna for meteorological stratospheric balloon payloads, but the achieved results can be extended to any quadrifilar helical antenna with shaped pattern. Size reduction close to 50% is reached while preserving major radiation pattern characteristics and good axial-ratio performance over a wide angular range.

A Broadband Folded Printed Quadrifilar Helical Antenna Employing a Novel Compact Planar Feeding Circuit

A broadband printed quadrifilar helical antenna employing a novel compact feeding circuit is proposed in this paper. This antenna presents an excellent axial ratio over a wide beamwidth, with a 29% bandwidth. A specific feeding circuit based on an aperture-coupled transition and including two 90° surface mount hybrids has been designed to be integrated with the quadrifilar antenna. Over the bandwidth, the measured reflection coefficient of the antenna fed by the wideband compact circuit has been found to be equal to or lower than -12 dB and the maximum gain varies between 1.5 and 2.7 dBic from 1.18 to 1.58 GHz. The half-power beamwidth is 150°, with an axial ratio below 3 dB over this range. The compactness of the feeding circuit allows small element spacing in array arrangements.