Sequential-phase Feeding Network Research Articles

A Broadband MS-Based Circularly Polarized Antenna Array Using Sequential-Phase Feeding Network.

This paper introduces the design of a circularly polarized metasurface-based antenna array for C-band satellite applications that owns broadband operation and high gain characteristics. The single radiating element comprises a Y-shape patch and an above-placed 2 × 2 unit-cell metasurface. Further improvement in operating bandwidth and broadside gain is achieved by arranging four single elements in a 2 × 2 configuration and a sequential-phase feed network. A prototype has been fabricated and measured to validate the feasibility of the proposed antenna array. The measured operating bandwidth is 20% (4.50-5.50 GHz), which is an overlap between a -10 dB impedance bandwidth of 29.8% (4.50-5.99 GHz) and a 3 dB axial ratio bandwidth of 20% (4.50-5.50 GHz). Across this operating band, the peak broadside gain is 10.5 dBi. Compared with the recently published studies, the proposed array is a prominent design for producing a wide operating bandwidth and relatively high gains while maintaining the overall compact dimensions.

A wideband and high-gain circularly polarized reconfigurable antenna array based on the solid-state plasma

In this paper, a wideband and high-gain circularly polarized (CP) antenna array with polarization-reconfigurable characteristics is presented based on the solid-state plasma (SSP). The proposed antenna is composed of switchable rotating radiation structures and a switchable feed network by simulating the different SSP branches. To investigate the CP operating mechanism, a reconfigurable CP element is designed through characteristic mode analysis (CMA). A switchable sequential-phase feed network is then proposed which can provide separately two rotational excitations. A spoof surface plasmon polariton (SSPP) is adopted for radiation patches to improve gain and axial ratio (AR) bandwidth. Finally, a high-gain and wideband 2 × 2 CP reconfigurable antenna array is designed. This array achieves left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) modes when different SSP branches are excited. The array has an overlapped impedance bandwidth of 61.9 % (3.17 to 6.01 GHz) and an overlapped AR bandwidth of 40.2 % (4.01 to 6.03 GHz) in two CP states, and the peak gain is 11.68 dBic.

A new broadband cross-dipole CP antenna with modified square-cavity reflector

ABSTRACTA new broadband cross-dipole CP antenna with modified square-cavity reflector is proposed in this work. The cross-dipole CP antenna is composed of four rotated L-shaped patches, a pair of vacant-quarter feeding loops as sequential-phase feeding network, two modified trapezoid-microstrip lines as impedance tuner, and a square-cavity reflector with four parasitic strips. Different from the traditional vacant-quarter rings, the modified vacant-quarter loops with trapezoid-microstrip lines are utilized to increase the impedance bandwidth (IBW) and provide 90° phase difference. First, the rotated L-shaped patches are used to obtain wide CP operation. Second, a square-cavity reflector is utilized for enhancing the radiation gains. Moreover, four parasitic strips are inserted into the reflector to increase the CP bandwidth. Therefore, multiple CP resonant points could be stimulated simultaneously by fully utilizing these elements, resulting in a wide CP performance. Finally, the proposed cross-dipole CP antenna has a wider −10 dB IBW of 100% (1.0–3.0, 2.0 GHz), broader 3-dB ARBW of 71.2% (1.25–2.65, 1.95 GHz), and a higher radiation gain, which can cover the WiBro (2.3–2.39 GHz) and GPS (L1 1.575 GHz) bands.

Dual-Band Circular-Polarized Microstrip Antenna for Ultrawideband Positioning in Smartphones With Flexible Liquid Crystal Polymer Process

This article proposes a dual-band circular-polarized (DBCP) microstrip antenna using flexible liquid crystal polymer (LCP) manufacturing process for ON-smartphone ultrawideband (UWB) positioning application. To achieve dual-band circular polarization in a low profile, the proposed antenna is designed with a cross-slot-loaded patch with four L-shaped feeding probes and a sequential phase feeding network. A circle of capacitive via fence is loaded surrounding the patch for area miniaturization, which is adaptive for the limited space of flexible printed circuit (FPC) in smartphones. Based on the UWB positioning protocol, a three-element antenna array is constructed in a low profile of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.015\lambda _{0}$ </tex-math></inline-formula> with required isolation of 17 dB. Experimental results show the overlapped bandwidth of the efficiency and the axial ratio (AR) covering the demand bands of 6.30–6.80 and 7.75–8.10 GHz. With the properties of dual wideband operation, circular polarization, and ultralow profile, the proposed antenna exhibits feasible solutions for the UWB positioning application in space-limited smartphones.

A High-Gain Circularly Polarized Antenna Array Based on a Chiral Metastructure

In this article, a chiral metastructure absorber (CMMA) is combined with a circularly polarized (CP) antenna array based on a sequential-phase feed network, and the differential absorption of left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) by CMMA unit is used to improve the axial ratio beamwidth (ARBW) of CP antenna array by absorbing the cross-polarization of the antenna array. The proposed CMMA unit achieves good circular dichroism at 4.9–5.2 GHz, which improves the ARBW of the antenna in this frequency band. In addition, the feed network of the antenna proposed in this article is in three-dimensional (3-D) form to reduce the coupling between the feed network and the radiation patches, so that higher gain can be obtained. The measured impedance bandwidth of the antenna is 80% (2.81–6.81 GHz), the axial ratio (AR) bandwidth is 70.8% (3.68–7.22 GHz), and the peak gain is 15.28 dBi.

Wideband Isotropic Antenna With Miniaturized Ground for Enhanced 3 dB Coverage Ratio

In this letter, a wideband three-dimensional (3-D) isotropic antenna is proposed with improved 3 dB coverage ratio. Based on the investigation about the effect of the metallic ground size on isotropic radiation, a compact sequential-phase feeding network made of lumped components with miniaturized ground is elaborately designed for wide operating bandwidth and enhanced 3 dB coverage ratio in 3-D space. In the measurement, the antenna prototype is with the size of 70 × 70 × 0.5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (0.23 × 0.23 × 0.0017 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ). The measured result shows that the proposed antenna provides the 6 dB gain variation fractional bandwidth of 4% and the 3 dB coverage ratio of more than 80%, leading to promising usage for wideband isotropic radiation applications.

Wearable Wideband Circularly Polarized Array Antenna for Off-Body Applications

A wideband circularlypolarized (CP) wearable antenna for 5 GHz (5.15–5.825 GHz) wireless body area network is presented and analyzed. The emphasis of this work is on the additional resonance generated by the mutual coupling of a 2×2 compact patch array. As the proposed antenna is fed by a sequential-phase feeding network, the resonance can be used to achieve unidirectional radiation with improved CP bandwidth. To alleviate the loading effects of the human body, a modified strip feedline, comprising two pairs of arc-shaped slots cut on the bottom ground, is introduced. Moreover, the adoption of textiles as substrate and conductor provides flexibility and conformability, allowing the antenna to be integrated with garments. The prototype with the dimensions of 40 mm × 40 mm × 4 mm (0.73 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.73 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.07 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) was fabricated. The measured results indicate that a wide impedance bandwidth of 43% (4.25–6.63 GHz), a half-power beamwidth of 60°, and a 3 dB AR bandwidth of 34% (4.71–6.67 GHz) are achieved. Furthermore, the antenna performance is proved to be stable under structural deformation and human body loading. Finally, transmission losses and link budgets are evaluated, enabling the antenna to be a robust solution for off-body communications.

A circularly polarized antenna array with sequential-phase feed network

In this paper, a simple broadband circularly polarized (CP) patch antenna design is proposed. The antenna uses a 2 × 2 array fed by a sequential-phase feed network to improve the axial ratio (AR) bandwidth and gain, and an L-shaped slot is used to remove the coupling between the feed network and the radiation patches. Similarly, to reduce coupling, the height between two substrates is discussed as an important parameter. The proposed antenna is fabricated to verify the simulated results. Measured results show that the impedance bandwidth is 65.2% (1.68–3.31 GHz), the AR bandwidth obtained at the same time is 61.6% (1.86–3.39 GHz), and the effective relative bandwidth is 58% (1.86–3.31 GHz), and the peak gain is about 7.13 dBi at 2.7 GHz.

Wideband circularly polarized array antenna based on weakly coupled sequential phase feed network

AbstractThis letter introduces a wideband circularly polarized (CP) array antenna for wireless communication application. The array consists of 2 × 2 sequentially rotated symmetric antenna elements and a wideband weakly coupled feed network providing stable 90° phase difference. By using the proposed feed network and introducing the slot coupling feed, the CP array antenna can achieve a wideband CP performance with a low profile of 0.03 λ0 (at 5.0 GHz). The proposed antenna exhibits the impedance bandwidth (IMBW) of 73.9%, axial ratio bandwidth (ARBW) of 53.6%, and 3‐dB gain bandwidth (GBW) of 60% with the peak gain of 10.4 dBi and the maximum efficiency of 82%. The measured results are in good agreement with the simulated results, indicating that a promising application in compact wideband C‐band wireless systems.

Broadband circularly polarized crossed‐dipole antenna and its array for long‐term evolution communication systems

The performance of a broadband circularly polarized crossed-dipole antenna for long-term evolution services is presented in this study. The antenna consists of a pair of trapezoidal-shape dipoles, four trapezoidal parasitic elements, and a pair of three-quarter printed rings that generate a 90° phase difference between the dipoles. The axial ratio (AR) bandwidth is extended using two principal factors in this article. The first one is using trapezoidal parasitic elements, and the second one is employing the feed network in the sequentially rotated technique. Its 2 × 2 array with a sequential-phase feeding network is introduced to achieve a noticeable improvement on the proposed dipole antenna performance. The measured results approve that the impedance and AR bandwidths of the proposed crossed-dipole antenna are 44% (1.95–3.05 GHz) for S11 < −10 dB and 31% (2.2–3 GHz) for AR ≤ 3 dB, respectively. Furthermore, by applying a 2 × 2 array structure for the proposed antenna, the impedance, and AR bandwidths increased by 63% and 31%, respectively. Indeed, using trapezoidal parasitic elements adjacent to the dipole arms leads to generating further surface currents and causes to extend the impedance. A sequential-phase feeding network is in charge of extending the AR bandwidth of the antenna simultaneously.

An array of staircase‐shaped circularly polarized DRA

A wide band circularly polarized (CP) aperture coupled staircase shaped wideband dielectric resonator antenna (SSCPDRA) array is implemented. The proposed array is composed of identical four SSCPDRA elements. The wideband CP and gain of the single element is enhanced by using 2 × 2 array with sequential phase feeding network. The measured results outputs emphasize that the proposed array is operated at frequency band from 8 to 12.3 GHz (43%). In addition, it has 3 dB axial ratio extended from 8.35 to 12.2 GHz (38.5%). Furthermore, the radiation pattern has broadside direction with the usability within the X-band applications.

Wideband circularly polarized aperture coupled DRA array with sequential-phase feed at X-band

A novel 2 × 2 wideband dielectric resonator antenna (DRA) array with circular polarization and fed with a sequential-phase feeding network at the X-band is presented in this paper. The proposed DRA array is fed by an aperture coupled feeding network. Each DRA element is constructed by joining two identical pieces of half-cylindrical shape; those are shifted with respect to each other to produce two orthogonal modes, in order to achieve a broadband circular polarization and wideband impedance matching simultaneously. The rigorous analysis and optimization processes throughout this paper are carried out numerically. The proposed array demonstrates a maximum realized gain of 10.3 dB. The measured matching bandwidth ranges from 8 to 12 GHz (40%), with about 37% 3-dB axial ratio bandwidth within the matching bandwidth. The quadruple DRA elements array is fabricated, and its scattering parameters and far-fields performance are measured to validate the numerical results. Acceptable agreement between the simulated and measured results is accomplished. It is demonstrated that the proposed antenna is a potential candidate for radar and satellite applications at X-band.

Wideband circularly polarized sequentially rotated microstrip antenna array with sequential-phase feeding network

A wideband 2 × 2 sequential-phase fed circularly polarized (CP) microstrip antenna array (MAA) with sequentially rotated elements is proposed. Firstly, the antenna element loaded with shorting pins is studied as compared to the traditional counterpart. Then, a feeding network is designed to be connected together in a sequential rotation manner, resulting in forming a four-port network to allow symmetrical positioning of CP microstrip patch elements. After that, straight strips are added to the feeding network in order to increase the distance and reduce coupling between array elements. They also play a role in improving the impedance matching of the array. Finally, the proposed antenna array is designed and simulated. The results are presented that its impedance bandwidth is about 36.3% at 24.1~34.8 GHz for |S 11 | < −10 dB and axial-ratio (AR) bandwidth is about 20.4% at 24.2~29.7 GHz for AR < 3 dB. Besides, a peak gain of 11.1 dBic is simulated over the operating frequency range, which is significantly improved compared to the classic and existing works.

Gain and bandwidth enhancements of sequential‐fed circularly polarized patch antenna array using multiple parasitic elements

This paper presents a circularly polarized (CP) antenna array with wideband operation and high gain characteristics. The single array element is composed of a slotted CP patch and parasitic elements. It has been found that besides improving the operating bandwidth (BW), properly choosing a number of parasitic elements can also contribute to a significant increase in the antenna gain over the entire operating band. For further boost in the performance, multiple array elements are arranged in 2 × 2 configuration and fed by a sequential-phase feeding network. In comparison with the related works in the literature, the proposed design shows approximately 3-dB higher gain. The design concept has been validated by experiments. The fabricated array has a measured operating BW of 28% (4.6-6.1 GHz) and a peak broadside gain of 15.8 dBic.

Compact bidirectional circularly polarized dedicated short range communication antenna for on‐board unit vehicle‐to‐everything applications

This article presents a newly circularly polarized (CP) antenna for V2X's dedicated short range communications applications. Its CP characteristic is enabled by a 70 Ω sequential phase feeding network and sequential rotation technique designed on top of the substrate. It has features of ≈90° phase difference in sequence between ports of S21 = 2.4°, S31 = −87°, S41 = −180°, and S51 = −276°, resulting in a 2.19 dB axial ratio centered at 5.9 GHz. The length of the SP feeding network to each ports designed in the different form of meander lines are the key to control the generated phase at the center frequency It also contributes to the smaller final size of 0.59λ × 0.59λ. The proposed antenna operated from 5.850 to 5.925 GHz with a gain between 4 and 6 dBi. The gains are radiated in bidirectional mode due to the presence of the complimentary dipoles located on the opposite side of the substrate. These features indicate the suitability of the proposed antenna in compliance to the ITS-G5 OBU V2X standard.

Circular polarization realization in array antennas by a modified sequential phase feeding mechanism of linearly polarized elements

AbstractNovel designs of a circularly polarized 2 × 2 and 4 × 4 slot array antennas (CPSAAs) are proposed. Sequential phase feed network composed of a section of 270° and four strips is utilized to feed the array structures. Array elements are simple linearly polarized wide slot antennas (WSAs) composed of simple radiating patches with truncation on four corners and slotted ground plane on substrate backside. Each WSA operates over the UWB frequency band of 3.1–10.6 GHz. When the WSAs are arranged in the form of 2 × 2 and 4 × 4 CPSAAs, frequency bands of 3–13.1 and 1.4–12.3 GHz are covered, respectively. More importantly, CP is generated at 4.5–8 and 4.6–8.8 GHz for 2 × 2 and 4 × 4 CPSAAs, respectively. This is while; the WSAs are linearly polarized elements. Higher gain values and wider bandwidths are obtained with respect to single WSA. Design process and performance analysis of the single and array antennas are discussed through the paper.

Compact broadband circularly polarized slot-patch antenna array

A simple design of circularly polarized slot-patch antenna array with broadband operation and compact size is presented in this article. The antenna element consists of a circular slot and a semicircular patch, which are etched on both sides of a substrate. For the gain and axial ratio (AR) bandwidth enhancement, its array antennas are implemented in a 2 × 2 arrangement and fed by a sequential-phase feeding network. The final 2 × 2 antenna array prototype with compact lateral dimension of 0.8λL × 0.8λL (λL is the lowest frequency within AR bandwidth) yielded a measured impedance bandwidth of 103.83% (2.76-8.72 GHz) and a measured AR bandwidth of 94.62% (2.45-6.85 GHz). The peak gain values within the AR bandwidth are from 2.85 to 8.71 dBi. A good agreement between the simulated and measured results is achieved. This antenna array is suitable for multiservice wireless systems covering WiMAX, WLAN and C-band applications such as satellite communications.

Circularly polarized antenna array with a new sequential phase feed network utilizing directional coupler

This is a presentation of a new design of circularly polarized (CP) antenna array having a wide axial ratio (AR) bandwidth and high-gain. It uses an innovative feed network which consists of compact directional couplers and a delay line describing a new kind of sequential phase (SP) feed network. Furthermore, in this work, we report and discuss the features of the feed network and single element. In the following, the single element antenna and the 2 × 2 CP antenna array are designed, prototyped and tested. The antenna array is designed by a multilayer microstrip structure with a compact size of 75 × 52 mm2. Moreover, a metal reflector is utilized to enhance the antenna gain and achieve a unidirectional radiation pattern over the operating frequency band. According to the experimental results, the CP antenna array has a return loss (RL) bandwidth of 2.42 GHz (5.83–8.25 GHz), AR bandwidth of 1.11 GHz (6.76–7.87 GHz), and peak gain of 12.15 dBic. It seems that the performance of the proposed design is admirable for C-band frequency.

Broadband circularly polarized slot antenna arrays using linked elliptical slots forC- andX-band applications

Compact broadband circularly polarized elliptical slot antenna arrays (CPESAAs) are devised based on 2 × 2 and 4 × 4 circularly polarized (CP) elliptical slot antennas and a sequential phase feed network. To realize the circular polarization, eight rectangular stubs are embedded in the feed structure to excite two orthogonal E vectors in 2 × 2 CPESAA configuration. Moreover, by taking four rectangular slots out from each array element, return loss and axial-ratio bandwidths are noticeably increased. The investigated simple array element has a compact size of 20 × 20 × 1 mm3. As well, 2 × 2 CPESAA occupies a compact size of 55 × 60 × 1 mm3, which operates within the frequency band 4.18–9.35 GHz. Thus, 76.4% of S11&lt; −10 dB and 51.4% of CP bandwidth (4.43–7.5 GHz) are covered. Moreover, proposed 4 × 4 CPESAA is printed on 110 × 110 × 1 mm3FR4 substrate and covers the frequency band of 1.15–12.98 GHz with CP at 2.95–8.82 GHz. Throughout the study, the design process of the proposed antenna arrays are presented and discussed in detail.

High-Gain Windmill-Shaped Circularly Polarized Antenna Using the High-Order Mode and Ground-Edge Diffraction

In this letter, the high-order mode and ground-edge diffraction of a slot antenna are used to achieve a high gain. To inhibit the multilobes at the high-order mode, ground-edge diffraction is utilized to form a single main lobe by changing the size of the ground plane of the slot radiator. Then, this slot antenna is employed to construct a windmill-shaped array antenna for circular polarization. A four-way sequential-phase feeding network is designed to feed the four slot elements, which are placed in orthogonal positions to form a windmill shape. A reflector is placed under the four slot elements to make the proposed antenna unidirectional. The slot elements are excited in the high-order resonant mode, instead of the fundamental resonant mode, and ground-edge diffraction of the slot elements is used to make the radiation pattern form a single strong lobe with increased gain at the +z -direction. The antenna is studied and designed using simulation and measurement. Measured results show that the proposed antenna has a common bandwidth (overlapping of the impedance bandwidth, the axial-ratio bandwidth, and the 1 dB gain bandwidth) of 4.73-5.53 GHz (0.8 GHz, 15.6%), a realized peak gain of 13.4 dBi, and an efficiency higher than 89.2%.