Planar Helical Antenna Research Articles

A Low-RCS and High-Gain Planar Circularly Polarized Cassegrain Meta-Antenna

Achieving highly directive radiation with broadband operation, low scattering, and thin profile for a circularly polarized (CP) antenna is particularly challenging and yet rarely reported. Here, we propose a strategy of a CP Cassegrain meta-antenna by combining a planar helical antenna, a metasurface main reflector, and a metamaterial subreflector. The main reflector is designed to achieve focusing for CP waves at 13 GHz. The subreflector is chessboard-configured chiral metamaterial slab composed of two different types of chiral meta-atoms, aiming to achieve spin- and direction-selective CP transmissions and reflections. The distance between two reflectors is half of focal length, which enables our antenna to be dubbed as a folded reflectarray. The low radar cross section (RCS) is achieved based on scattering cancellation technique by realizing near 180° reflection phase difference between two neighboring chessboard submeta-atoms. Thanks to the architecture of the two reflectors, the proposed antenna exhibits high gain and low profile simultaneously according to image theory. For verification, a planar CP Cassegrain antenna, excited by a left-handed CP (LCP) planar helical antenna, is numerically studied, fabricated, and experimentally measured. Numerical results are in good agreement with the experimental ones, showing a peak right-handed CP (RCP) gain of 26.6 dBi at 12.6 GHz. Furthermore, the backward monostatic RCS of the antenna is dramatically reduced over −10 dB in a broad bandwidth from 8.4 to 15.7 GHz when it is illuminated by an LCP planar wave. Our proposed Cassegrain antenna features simultaneously broadband, high gain, low profile, and low RCS, providing a new avenue to low-profile CP reflectarrays with invisibility.

A 28 GHz Broadband Helical Inspired End-Fire Antenna and Its MIMO Configuration for 5G Pattern Diversity Applications

In this paper, an end-fire antenna for 28 GHz broadband communications is proposed with its multiple-input-multiple-output (MIMO) configuration for pattern diversity applications in 5G communication systems and the Internet of Things (IoT). The antenna comprises a simple geometrical structure inspired by a conventional planar helical antenna without utilizing any vias. The presented antenna is printed on both sides of a very thin high-frequency substrate (Rogers RO4003, εr = 3.38) with a thickness of 0.203 mm. Moreover, its MIMO configuration is characterized by reasonable gain, high isolation, good envelope correlation coefficient, broad bandwidth, and high diversity gain. To verify the performance of the proposed antenna, it was fabricated and verified by experimental measurements. Notably, the antenna offers a wide −10 dB measured impedance ranging from 26.25 GHz to 30.14 GHz, covering the frequency band allocated for 5G communication systems with a measured peak gain of 5.83 dB. Furthermore, a performance comparison with the state-of-the-art mm-wave end-fire antennas in terms of operational bandwidth, electrical size, and various MIMO performance parameters shows the worth of the proposed work.

V-Band End-Fire Radiating Planar Micromachined Helical Antenna Using Through-Glass Silicon Via (TGSV) Technology

In this paper, we demonstrate a V-band planar micromachined helical antenna (PHA) with end-fire radiation on the glass substrate. The planar rectangular helical configuration is realized using the novel through-glass silicon via (TGSV) technology. The proposed micromachined antenna is designed and fabricated on a borosilicate glass substrate of thickness 350 μm, which has a very low-dielectric loss compared to silicon at millimeter-wave bands. The proposed PHA is fed by a microstrip line, and the planar helical configuration with 3.25 turns with a truncated ground plane is designed for achieving wideband end-fire radiation with seven tungsten-coated silicon vias and six connected gold arm patterns, which are fabricated using the TGSV technology. The electrical length of the proposed antenna is (3 λ o ×1.4 λ o ). The designed antenna operates at the center frequency of 58 GHz. A prototype of the proposed antenna is fabricated by micromachining technology and tested. The simulated and measured results show that the proposed antenna has a wide operational bandwidth of 50.3 to 65 GHz for |S 11 | <; -10 dB with a fractional bandwidth (FBW) of 25.5%. The measured peak gain is 6.3 dBi, and measured efficiency is 62% at the center frequency of 58 GHz. All measurements are in close agreement with simulated results. The proposed planar helical antenna with end-fire radiation is useful for applications in traveling-wave-tubes operating in millimeter-wave and higher frequencies, millimeter-wave on-board wireless communication, radar imaging, and tracking applications.

Planar Helical Antenna of Circular Polarization

A planar helical antenna is presented for achieving wideband end-fire radiation of circular polarization while maintaining a very low profile. The helix is formed using printed strips with straight-edge connections implemented by plated via-holes. The currents flowing on the strips and along via-holes of the helix contribute to the horizontal and vertical polarizations, respectively. Besides, the current on the ground plane is utilized to weaken the strong amplitude of the horizontal electric field generated by the one on the strips. Thus, a good circular polarization can be achieved. Furthermore, a tapered helix and conducting side-walls are employed to broaden the axial ratio (AR) bandwidth as well as to improve the end-fire radiation pattern. The designed antenna operates at the center frequency of 10 GHz. Simulated results show that the planar helical antenna achieves wide-impedance bandwidth ( $\vert S_{11} \vert ) from 7.4 to 12.8 GHz (54%) and 3-dB AR bandwidth from 8.2 to 11.6 GHz (34%), while retaining a thickness of only $0.11{{{\lambda }}_0}$ at the center frequency. A prototype of the proposed antenna is fabricated and tested. Measured results are in good agreement with simulated ones.

Nanosecond pulsed laser processing circuits on the copper clad polyimide

Precision processing of miniaturised circuits on the surface of three-dimensional (3-D) structure is of great importance for the telecommunication equipment. Laser micro-machining technologies have led the way in the development of innovative solutions in manufacturing high-accuracy circuits. In this paper, fine strip-line of planar helical antenna on the copper clad polyimide (CCPI) is fabricated based on the application of nanosecond pulse laser. In order to obtain the optimised processing parameters for planar helical antenna, ablation experiments of single grooves are performed and the effect of process parameters, such as laser wavelength, single pulse energy density, repetition frequency, scanning speed, laser spot overlap coefficient and milling times, are quantitively analysed. And the strip-line of planar helical antenna is processed under the optimised condition (laser single pulse energy density is 25 J/cm2, frequency is 30 kHz, laser spot overlap coefficient is 0.9, and milling times is 1). Experimental results indicate that the minimum width of micro-strip can reach 50 μm, and form error of strip-line edge processed by nanosecond pulse laser is less than ±10 μm, which could match the geometric accuracy requirement of the micro-strip antenna.