Circularly Polarized Radiation Research Articles

A High-Gain circularly polarized magnetoelectric dipole antenna array with metallic radiating structure for Millimeter-Wave applications

A high-gain circularly polarized (CP) magnetoelectric (ME) dipole antenna with metallic radiating structure is presented. The proposed CP antenna element consists of two pairs of metallic posts with a supporting metallic plate, a metallic air-filled elliptical cavity, and a feeding slot on the bottom substrate integrated waveguide (SIW). The two pairs of modified rectangular metallic posts combined with the gaps between them act as radiating ME-dipoles which are surrounded by a metallic air-filled elliptical cavity. The above-mentioned radiating structures are fed by a modified cross-shaped coupling slot etched on the bottom feeding SIW to generate CP radiation, where loading the elliptical metallic cavity significantly improve the CP performance of the antenna element. Then, a 4 × 4 antenna array with full-corporate feeding network is designed, fabricated, and measured, which has an impedance bandwidth of 18.9 % from 37.4 to 45.2 GHz and a 3-dB axial ratio (AR) bandwidth of 14.2 % from 36 to 41.5 GHz. Thanks to the all-metal radiating structures, a maximum measured gain of 20.4 dBic has been achieved. The measured and simulated results are in good agreement.

A Wide-Band Circularly Polarized Euler Spiral Dielectric Resonator Antenna for X/Ku-Band Applications

This paper puts forward a low-profile, circularly polarized (CP), wideband Euler’s Spiral Dielectric Resonator Antenna (ES-DRA) having a footprint of 0.68 λ × 0.68 λ × 0.096 λ and operating in X and Ku-band (8.26–14 GHz). A cross-shaped aperture is used to couple the power from 50 Ω walking stick-shaped microstrip line to the ES-DRA. The antenna generates circular polarization radiation in the frequency band 10.47–11.69 GHz and has a peak gain of 8.1 dBic. There is a good matching between radiation and total efficiency in the operating band. The antenna can be put to use in weather mapping and detecting, long-range tracking radar and missile applications. The prototype has been fabricated and tested for experimental validation and the results are in good coherence with the simulated ones.

A single-layer multimode high gain circularly polarized metasurface antenna using CMA for C-band applications

Abstract This article presents an innovative design for a low-profile, high-gain circularly polarized (CP) antenna using a single-layer metasurface (MTS). The proposed design incorporates an MTS layer, comprising a 4 × 4 array of hexagonal-shaped patches, printed on the top layer of the substrate. The bottom layer features a coplanar waveguide-fed slotted ground. Circular polarization and broadside radiation are achieved through the application of characteristic mode analysis (CMA). CMA is employed to simultaneously excite desired modes, aiming for wideband circular polarization and gain enhancement. Experimental results validate the effectiveness of the design, with compact dimensions of 0.67λ0 × 0.67λ0 × 0.04λ0. The measurements demonstrate an impressive impedance bandwidth of 84.3% within the 3.7–9.1 GHz. Additionally, a 3-dB axial ratio bandwidth of 18.6% is observed between 4.96 and 5.98 GHz and 3.74% between 8.38 and 8.7 GHz. The antenna exhibits excellent radiation pattern characteristics, featuring a maximum gain of 10.08 dBi at 7.1 GHz. The radiation pattern is symmetrical with broadside directionality, making the antenna well-suited for sensing applications.

A low‐profile circularly polarized cavity‐based waveguide aperture antenna

AbstractThis article proposes a new design of a circularly polarized (CP) aperture antenna based on a dual‐mode rectangular waveguide cavity‐resonator. A capacitive iris is employed to attain a strong coupling between the cavity and the input port, resulting in a larger fractional bandwidth (FBW) than a conventional aperture antenna. Another capacitive iris is embedded at the corner of the radiating aperture and extended into the cavity to maintain equal amplitude and a phase difference of 90° between the radiated electric (E) fields of the TE101 and TE110 modes, and thus yielding CP radiation. The proposed antenna has been fabricated using a computer numerical control machine. The antenna has an FBW of 18% at center frequency (f0) f0 = 10 GHz when the reflection coefficient (S11) S11 = −10 dB. The 3‐dB axial ratio bandwidth is 7%. A gain of 8.0 dBic is found at 10.06 GHz. The low profile and competitive performance of the antenna make it a good candidate in radar applications.

Design of dual circular polarized stacked patch antenna for BeiDou navigation satellite systems

In this article, a design of two-layered, dual circular-polarization (CP) and dual-band path antenna is presented for BeiDou navigation satellite (BDS) system applications. A single 50-Ω Co-axial probe feeding arrangement is employed to achieve dual-band operation and it feeds both the antennas simultaneously. This mode introduces the CP radiation on both upper (RHCP) and lower (LHCP) operation bands. The impedance bandwidth is further widened by accommodating two semi-circular stubs on the top patch. The fabricated and experimentally validated prototype radiates at 1.82 and 3.45 GHz (center frequency). The upper and lower operating band exhibits right and left-handed CP radiations, which constructs dual-band operation. The fabricated prototype has a physical size of πr2 × 0.024 λg with an antenna profile of 2.38 mm (0.024 λg). The experimentally validated upper and lower bands impedance bandwidth with |S11| < −10 dB are 21.1% and 11.1%, respectively. The fabricated prototype is a good candidate to use in BDS applications. [Q2

Compact Integrated Circular Polarization Filtering Antenna based on SIW Cavity

In this paper, a compact integrated circular polarization filtering antenna is proposed based on substrate integrated waveguide (SIW) cavity. Firstly, a dual-mode (TE102 and TE201 modes) rectangular cavity is utilized as a common feeding cavity to achieve a dual-mode filtering response. And then, an additional rectangular patch with a slot is coupled from the feeding cavity for circular polarization radiation. To verify the proposed concept, a prototype circular polarization filtering antenna is simulated. The circular polarized filtering antenna resonates at 4.225 GHz with a low cross-polarization and a high gain of 7.23 dBi.

Compact Series-fed Circularly-polarized Patch Array basedon Microstrip Line

A compact single-layer circularly polarized (CP) antenna array is proposed in this paper for 5G/6G applications. The conventional microstrip line is modified as a feeding network by periodically and alternatively loading field blocking stubs, producing a linearly polarized in-phase radiative field aperture. By adding CP corner-truncated patches beside these in-phase fields, a linear high-gain CP antenna array excited by a single feed is obtained. The feasibility of the proposed design is demonstrated through the fabrication and measurement of a 16-element linear array. The results indicate that the 3 dB axial ratio bandwidth is 3.5% (19.60∼20.30 GHz), the -10 dB impedance bandwidth totally covers the 3 dB axial ratio bandwidth, and the peak realized gain is 14.9 dBi under an antenna length of 5.69λ0. This proposed strategy provides a very compact antenna structure to achieve high-gain CP radiation without the requirement of impedance transformers, phase shifters, and open-stop-band suppressing measures. Moreover, the antenna has a per-unit-length CP gain of 5.5/λ0, which is superior to many single-layer high-gain CPantennas.

An all‐metal wideband circularly polarized single‐patch antenna based on TM11 mode

AbstractThis paper proposes an all‐metal wideband circularly polarized (CP) single‐patch antenna based on TM11 mode. The conventional square patch is divided into four small square patch units by loading metal shorting walls under the two vertical centerlines. The shorting walls are windowed to facilitate coupling between the adjacent units. When the TM11 mode is excited, the coupling windows not only distribute energy but also provide the 90° phase difference required for CP radiation. An additional feeding network is not required, and its profile is less than 0.05λ0 (λ0 is the free space wavelength at the center frequency). Three minima in the axial ratio (AR) response are present. The results show that right‐hand circularly polarized (RHCP) radiation is achieved. The measured 3 dB AR bandwidth is 6.9%, ranging from 1.52 to 1.62 GHz, and the RHCP realized peak gain is 7.72 dBic. An all‐metal construction suitable for satellite communication systems is designed that has superior performance in harsh space environments.

Dual band dual circularly polarized patch antenna for Ku-band applications

This paper proposes a duplex antenna, with four square patches to form a sequential rotating array, which can generate dual circular polarization radiation. A feeding network consisting of power dividers, phase shifters and couplers feeds the antenna with ±90° phase difference and achieves dual circular polarization. A band stop filter with low reflection is employed in the receive port to increase the isolation in the transmitting band (14–14.5 GHz) to over 30 dB. The receive port achieves a gain of over 4.8 dBi and an axial ratio under 3 dB in the receiving band (10.7–12.7 GHz). The transmit port has a gain of more than 5.1 dBi and a 3 dB axial ratio in the whole frequency band (10.5–15 GHz).

Compact and bandwidth-enhanced circular-polarized dipole antenna for 5G base-station applications

ABSTRACT A miniaturized and wideband circular-polarized (CP) dipole antenna with couple-feed has been developed for 5G base-station applications. In this design, two novel L-shaped short stubs working as the couple feed are introduced to excite the orthogonal dipole with the orthogonal phase difference. Therefore, CP radiation is realized on the orthogonally arranged dipoles. In addition, a stub-loaded square-ring dipole is utilized to generate another resonant frequency at low frequency, which broaden the working bandwidth and achieve the miniaturization design. To further expand the impedance and axial ratio bandwidths, four branch lines are adopted in the center of crossed square-loops dipoles. The proposed CP antenna using couple feed was finally fabricated and tested. The simulated and measured impedance bandwidth for |S11| < −10 dB is 65.0% from 1.55 to 3.05 GHz. The measured 3 dB axial ratio bandwidth is 37.5% (1.95–2.85 GHz). The measured results prove that this CP antenna can be applied to wideband base-station applications.

Circularly-Polarized Ring Slot Antenna Fed by a V-Shaped Coupling Strip

A design for circularly-polarized (CP) ring slot antennas is described. The antenna is fed by a V-shaped coupling strip loaded with a resistor. For the slot antenna with a thin slot width, the proposed feeding mechanism can directly generate good CP radiation and fine tuning of antenna parameters is unnecessary. When the slot width is increased, CP radiation with low axial ratio can also be obtained as long as the included angle of the V-shaped coupling strip is properly adjusted. Numerical analyses of the key parameters of the V-shaped coupling strip are provided. A number of the CP prototypes with various slot widths are fabricated. Experimental results demonstrate that the feeding mechanism can give good CP performances for the case that the slot width is varied from 0.008 to 0.09 e0, and the antenna gain is not significantly degraded when the loading resistance is small enough.

A low-profile wideband circularly polarized metasurface antenna based on characteristic mode analysis

Abstract A low-profile wideband circularly polarized (CP) metasurface antenna is demonstrated for C-band applications. The metasurface consists of 4 × 4 square patches with Z-shaped slots. Characteristic mode analysis is used to investigate the modal behavior of the metasurface, and a pair of degenerate modes is chosen as the operating modes. The CP radiation is realized by exciting a pair of degenerate modes of the metasurface through a slot antenna, which is used as a feed structure with a 90° phase difference. The CP bandwidth is further widened by combining the resonance modes of the metasurface and slot antenna. The measured results show that the −10 dB impedance bandwidth of the antenna is 3.47–4.76 GHz, and the 3 dB axial ratio bandwidth is 3.5–4.9 GHz with a peak gain of 6.9 dBic. Moreover, the antenna exhibits well left-hand CP radiation performances with a low profile of 0.046λ0.

Circularly‐Polarized Laser Equivalent to Two Phase‐Shifted Linearly‐Polarized Sources

AbstractCompact circularly‐polarized (CP) light sources are important for chirality‐based applications at the chip level. The CP light is conventionally generated by passing the linearly‐polarized (LP) one through quarter wave plates which are too thick for packed integrations. In this work, the in‐plane submicron phase shifter substitutes the quarter‐wave plate in the creation of CP light. After the lasing field of a holed microdisk is coupled into the nearby waveguide and phase shifter, it is guided into two grating couplers that output orthogonally LP waves vertically. The two LP waves are phase‐shifted by and combine into the coherent CP radiation in the far‐field zone. Experimentally, the fabricated devices exhibit a degree of circular polarization as high as 74%. This device scheme is simple and effective in that it relies on no extrinsic materials, large‐area auxiliary structures, or specialized operation conditions critical for CP radiation. The compatibility issues for integrated photonic systems are of less concern in such schemes.

Wideband single‐fed circularly polarised patch antenna

AbstractA two‐layered wideband single‐fed circularly polarised (CP) antenna is presented by the authors. A single‐fed corner‐truncated square patch with four identical rectangular matching branches acts as a bottom‐driven patch to generate CP radiation. To broaden the 3‐dB axial ratio (AR) bandwidth, a similar patch with a larger size is loaded atop the driven patch as a parasitic patch. The measured results show that the proposed CP antenna has a 17.9% impedance bandwidth from 2.13 to 2.55 GHz and an 11% 3‐dB AR bandwidth from 2.15 to 2.4 GHz, respectively. The measured total gain is 7.1 dBic. The results indicate that the proposed antenna is a good candidate for Wireless Local Area Network band applications.

CRLH‐TL‐loaded metamaterial antenna with frequency band and polarization reconfigurability

SummaryIn this communication, an asymmetric co‐planar waveguide (ACPW)–fed composite right–left‐handed transmission line (CRLH‐TL)–based frequency band and polarization reconfigurable antenna (RA) is presented. The reconfigurability is achieved by using a PIN diode. When the diode is in OFF state, meander line works as part of ground. Hence, the antenna is like a circular patch antenna working at 5.15 GHz. In the ON state, the antenna works as a CRLH‐TL‐based antenna with an additional lower band resonating at 2.45 GHz. The antenna also has circular polarization (CP) property. The lower 2.4 GHz band is covering for IEEE 802.11 b/g/n/ax/be applications, whereas the higher band is covering the WiFi bands of IEEE 802.11a/h/n/ac/ax/be applications with CP radiation (upper band). This antenna is effective in a scattering environment such as in urban areas and indoor communication.

Three-Dimensional Printed mm-Wave Circularly Polarized Filtering Antenna With Flexible Design and Spurious Suppression

In this communication, a 3-D printed circularly polarized (CP) filtering antenna with spurious suppression for 5G mm-wave applications is presented. First, a composite resonator, serving as both the last-stage resonator of a waveguide filter and an aperture antenna, is utilized to realize a filtering linearly polarized (LP) antenna. The 4 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> -order electric cross-coupling topology is employed to generate two radiation nulls at both sides of the passband, enhancing the selectivity. Then, a polarizer is presented and placed in front of the LP antenna to obtain the CP radiation. The operating principles of the polarizer are analyzed in detail, which features flexible size and insensitivity to the original filtering response. To demonstrate the concept, three filtering CP antennas with different polarizer dimensions are designed, exhibiting similar responses. After that, to suppress spurious modes and extend the spurious-free region, the defected ground structures (DGSs) are introduced. Finally, all three CP antennas are fabricated using 3-D printing and tested. Measured results show that 10 dB return loss and 3 dB AR bandwidths for all antennas are about 7% and 9%, respectively.

A Circularly-polarized Patch Antenna for BDS Applications

The BDS (Beidou) Navigation Satellite System has been a powerful tool in real-time navigation and positioning. In the transitional stage between BDS-2 and BDS-3, it would be a top priority to ensure the antenna is compatible with the two systems. In our investigations, a circularly-polarized (CP) patch antenna is proposed for receiving B1I signals. This antenna is a newly designed slit-loaded square patch structure. The T-shape structure with F-shape slots is deployed on each edge of the antenna, and a single feed is employed to excite right-hand CP radiation. In simulations, all the parameters of the antenna are optimized through Ansys HFSS. In experiments, the processed antenna is further testified, where the measured bandwidth is compared with the simulated one to verify the effectiveness of the antenna.

An ultra‐wideband dual circularly polarized slot antenna with high isolation

SummaryAn ultra‐wideband dual circularly polarized (CP) slot antenna with high isolation is presented. Two L‐shaped probes are on the upper layer, both a ladder strip outside and a bent strip in the center on the bottom layer. The L‐shaped probes and the ladder strip result in four impedance resonance modes, and the bent strip moderates real and imaginary impedances to achieve an ultrawide impedance bandwidth. Furthermore, two L‐shaped strips on the ladder strip make two linear polarized Modes 1 and 2 into two CP modes at the low‐ and mid‐frequency bands. Meanwhile, the bent strip combined with the L‐shaped probes creates the third CP resonance mode at the high‐frequency band. The cutting corner and bent slots on the ladder strip change the amplitude and the phase of the electric fields Ex and Ey to realize ultra‐wideband CP radiation. In addition, the port–port isolation is enhanced because the currents are concentrated on the bent strip, and the coupling current path is cut off with the bent slot. The fabricated antenna achieves a −10‐dB impedance bandwidth of 111% (1.7–5.94 GHz), a 3‐dB axial ratio bandwidth of 101% (1.7–5.2 GHz), and a port–port isolation of better than 20 dB. Besides, our antenna obtains a high peak gain of 8.1 dBi and a lower profile of 0.004 λL, where λL is the lowest frequency wavelength of the operating bands in vacuum. These performances make the proposed design competitive for wireless communications.

A 1-bit electronically reconfigurable beam steerable metasurface reflectarray with multiple polarization manipulations

A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the two PIN diodes between ON and OFF states, the isotropic and anisotropic reflections can be flexibly achieved. For either the isotropic reflection or the anisotropic reflection, the two operation states achieve the reflection coefficients with approximately equal magnitude and 180° out of phase, thus giving rise to the isotropic/anisotropic 1-bit metasurface unit cells. With the 1-bit unit cells, a 12-by-12 metasurface reflectarray is optimally designed and fabricated. Under either y- or x-polarized incident wave illumination, the reflectarray can achieve the co-polarized and cross-polarized beam scanning, respectively, with the peak gains of 20.08 dBi and 17.26 dBi within the scan range of about ±50°. With the right-handed circular polarization (RHCP) excitation, the left-handed circular polarization (LHCP) radiation with the peak gain of 16.98 dBic can be achieved within the scan range of ±50°. Good agreement between the experimental results and the simulation results are observed for 2D beam steering and polarization manipulation capabilities.

Low-profile shared-aperture metasurface array antenna with ultra-wideband radar cross section reduction and circularly polarization

This paper proposes a circularly-polarized (CP) metasurface antenna with ultra-wideband radar cross section (RCS) reduction. Initially, the relationship between RCS reduction and phase difference with different reflection amplitudes is analyzed theoretically. Inspired by the shared-aperture principle, a high-frequency resistive layer is introduced into the antenna element to further fulfill ultra-wideband RCS reduction and low-profile requirements. Numerical simulations demonstrate that the inserted layer has no effect on the radiation performance of the antenna array. Then, the proposed element and its orthogonal unit are arranged in a checkerboard pattern for good CP radiation. In this configuration, the proposed metasurface array antenna has a maximum gain of 16.7 dBi with 72.1% aperture efficiency. The bandwidth of 5 dB RCS reduction with x- and y-polarized incidences is 7.10–17.95 GHz and 7.34–17.85 GHz, respectively. The proposed design is verified by the fabrication of prototype antennas and measurements.