High Gain Circularly Polarized Research Articles

High-Gain Circularly Polarized 500–750 GHz Lens Antenna Enabled by Silicon Micromachining

High-Gain Circularly Polarized 500–750 GHz Lens Antenna Enabled by Silicon Micromachining

Development of Compact Wideband and High Gain Circularly Polarized Antenna for C-Band Applications

Development of Compact Wideband and High Gain Circularly Polarized Antenna for C-Band Applications

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.

High Gain Circularly Polarized Array Antenna Based on High-Order Mode ESIC for 5G Millimeter-wave Application

High Gain Circularly Polarized Array Antenna Based on High-Order Mode ESIC for 5G Millimeter-wave Application

A Compact High-Gain Circularly Polarized Wideband Antenna Array with Sequential Phase Feed and Truncated Ground for ISM, 5G Mid-Band and Ku-Band Applications

A Compact High-Gain Circularly Polarized Wideband Antenna Array with Sequential Phase Feed and Truncated Ground for ISM, 5G Mid-Band and Ku-Band Applications

Development of a Broadband and High-Gain Circularly Polarized Array of Multilayer Slot Antennas for X-Band Wireless Communication Networks

This paper presents a wideband cavity-backed slot antenna array designed for X-band wireless communication systems. The antenna element consists of a circular slot combined with a cross-slotted patch; both are fed by an L-shaped microstrip line through proximity coupling to extend the impedance bandwidth and gain. The reduction of beam squint in the radiation patterns, caused by the asymmetric feed line, is achieved through intelligent optimization of the dimensions and position of the cross slot on the patch. Additionally, a back cavity is included to provide unidirectional radiation and enhance gain. The antenna exhibits right-hand circularly polarized (RHCP) radiation patterns with high gain over a wideband frequency range. To further improve the axial ratio (AR) bandwidth and gain, the antenna is utilized in a 2 × 2 array configuration with a sequential rotation feed network. The overall dimensions of the proposed array are 1.42 λ 0 × 1.42 λ 0 × 0.45 λ 0 , where λ 0 represents the wavelength at the center frequency of 10 GHz. The fabricated array is then tested, and the measurements show an impedance bandwidth of 60% (7 GHz-13 GHz) with S 11 < − 10 dB, a 3 dB AR bandwidth of 42% (7.45-11.65 GHz), and a peak gain of 11.14 dB. The simulated and measured results exhibit good agreement, validating the effectiveness of the design.

Characteristic Mode Inspired Broadband Circularly Polarized Folded Transmitarray Antenna

The circularly polarized (CP) antennas with high gains have gained growing interest due to their significant advantages, but the existing works usually suffer from narrow bandwidths. In this work, a novel circularly polarized folded transmitarray antenna (CPFTA) inspired by the characteristic mode analysis (CMA) method is proposed to achieve a broadband and high-gain CP radiation. The proposed CPFTA consists of a top-layer multifunctional metasurface (MTS), a bottom-layer polarization conversion metasurface (PCM) integrated with a linearly polarized (LP) microstrip feed source. Enabled by the CMA, the unit cell etched with an asymmetric U-slot of the MTS is optimized to generate two pairs of CP modes to broaden the bandwidth of the CPFTA. Moreover, a modified broadband E-shaped LP microstrip antenna is integrated with the PCM, resulting in a compact profile. A CPFTA prototype is fabricated and characterized to verify the effectiveness of the design. The measured results show that the fabricated antenna could obtain an impedance bandwidth of 31.7%, a 3 dB axial ratio (AR) bandwidth of 36.5%, and a 3 dB gain bandwidth of 30.1% with a peak gain of 22.35 dBic at 9.55 GHz.

Broadband High-Gain Circularly Polarized Antenna for Conformal Applications

A broadband high gain circularly polarized (CP) antenna with low profile for conformal applications is proposed. The antenna is composed of a complete ground plane, a loop patch, a feeding patch and four parasitic patches. The loop patch with a sequential phase difference of 90 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> is designed to achieve circular polarization resonating in TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{11}$</tex-math></inline-formula> mode. The four parasitic patches surrounding the loop patch are designed to excite another CP resonant mode, which will widen the bandwidth and improve the gain. To verify the conformal capability of the proposed antenna, the performance under different bending radii is compared and discussed. Finally, the proposed antenna with a profile of 0.054 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula> is the free-space wavelength at the operation frequency of 5.5 GHz) is fabricated and measured. The measured -10 dB impedance bandwidth is 34.8%, 3 dB axial-ratio (AR) bandwidth is 20%, and peak gain is 11.2 dBic.

Subwavelength-Cavity High-Gain Circularly Polarized Antenna with Planar Metamaterials

We present a specific subwavelength-cavity high-gain circularly polarized ultra-thin antenna made of planar metamaterials. The antenna is designed to operate at 2.80 GHz with a fixed thickness of approximately 1/6 of the operating wavelength in free space. The asymmetric unit cells of the metamaterial antenna exhibit two characteristics, namely, negative permeability and polarization selection. A linear-polarization micro-strip patch, which can realize circular polarization without a complicated feeding network, is embedded in the cavity as a feed. The circular polarization mode of the antenna can be changed by simply rotating the planar metamaterial horizontally. Simulations and experiments conducted on this antenna yielded results that are in good agreement with each other. This new subwavelength planar antenna can have potentially important applications in communication, early warning systems, and radio observation.

A Wideband and High-Gain Circularly Polarized Antenna Array for Radio-Frequency Energy Harvesting Applications

A wideband millimeter-wave (mmWave) circularly polarized (CP) complementary antenna array is proposed herein for radio-frequency energy harvesting (RFEH) applications. The element is constructed of a CP magneto-electric (ME)-dipole antenna and innovatively introduces the complementary source technique to improve the CP radiation performance. The detailed analyses are provided to elaborate the operating principles of the element. Simulated results for the element reveal an impedance bandwidth of 25.7%, a 3-dB axial ratio (AR) bandwidth of 24.8%, and a gain of 8.7 ± 1.6 dBic over the spectrum. The element shows the stable radiation pattern and wide AR/impedance overlapping bandwidth (33.87–43.15 GHz) for RFEH applications covering the 35-, 37-, and 39-GHz bands. To enhance the gain for practical applications, the element is employed in the design, fabrication, and testing of a planar <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> 4 array fed by a full-corporate substrate-integrated waveguide (SIW) network. Measured results indicate that the array achieves an impedance bandwidth of 20.2%, a 3-dB AR bandwidth of 24.3%, and a 3-dB gain bandwidth of 22.8%. Thus, the proposed array features a low profile and excellent performance, which makes it a desirable candidate for mmWave RFEH applications.

A High-Gain Circularly Polarized Filtering Stacked Patch Antenna

A high-gain circularly polarized (CP) filtering stacked patch antenna with independently controllable radiation nulls is designed without an additional filtering circuit/network in this letter. The lower radiation patch consists of a square outer loop and a three-quarter circular inner ring to realize CP radiation, with the inner ring connected to two adjacent edges of the outer loop. In addition, the upper stacked patch provides improved impedance matching and CP characteristics within the passband. Furthermore, a U-slot and square annular slot are etched on the lower and upper patch to generate two radiation nulls and obtain a filtering characteristic in the lower and upper stopband, respectively. A prototype is fabricated and measured, and the measured results show that the proposed antenna can provide an impedance bandwidth of 15.2% (1.83-2.13 GHz), an axial ratio bandwidth of 8.2% (1.87-2.03 GHz), and a gain higher than 7.0 dBi.

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.

A HIGH GAIN CIRCULARLY POLARIZED (CP) ANTENNA ARRAY USING SEQUENTIAL PHASE (SP) ROTATION TECHNIQUE FOR WLAN APPLICATIONS

This paper designs and investigates a high gain circularly polarized 2 &amp;times; 2 antenna array for wireless applications using the sequential phase rotation technique. The feed network utilizes four rectangular lines of equal width and three 90&amp;deg; arcs. The length of all elements is equal to &amp;lambda;&lt;sub&gt;g&lt;/sub&gt;/4 to provide 0&amp;deg;, 90&amp;deg;, 180&amp;deg;, and 270&amp;deg; phase differences at the four outputs of feed network to increase the axial ratio(AR) bandwidth and purity. Four corner truncated patch elements are connected to the feed network to fulfill the 2 &amp;times; 2 antenna array design. The proposed design operates with an impedance bandwidth of 1.1 GHz from 4.9 GHz to 6 GHz bandwith and an AR bandwidth of 0.8 GHz from 5 GHz to 5.8 GHz band. The maximum measured gain of the antenna array is observed as 8.9 dBic in the operating band. The antenna array was prototyped and tested to validate its performance. This array is well suitable for high gain WLAN applications.

High-Gain Circularly Polarized Antenna Array for Full Incident Angle Coverage in RF Energy Harvesting

In this paper, a high-gain circularly polarized (CP) hexagonal antenna array is proposed for RF energy-harvesting applications. The hexagonal antenna array is intended to operate at the frequency of 5.8 GHz. It is composed of 6 multilayer substrate CP antennas excited by an X-shaped aperture-coupling feed structure. A frequency selective surface (FSS) was added to further improve the gain, resulting in a maximum gain of 12.7 dBi per element. The main advantage of the proposed hexagonal antenna array is the ability to cover 360 degrees in the azimuth plane with a high gain in all directions without the use of any additional circuitry, allowing the effective absorption of ambient RF energy. A prototype was fabricated and measured, and a good agreement with the simulation results is achieved. In addition, a rectifier is used to convert RF energy absorbed by the antenna into DC energy at the frequency of 5.8 GHz. The measured RF-to-DC conversion efficiency of 44.5% and a DC output voltage of 423 mV at -10 dBm are observed. The performance of the rectenna array with one and six rectifiers has been demonstrated. With the use of a DC combiner, the total RF to DC efficiency of the array is 67.75%, with a DC output voltage of 1.115 V from -10 dBm has been recorded. Due to the immunity to misalignment of the CP antenna, the proposed rectenna array is very suitable for wireless power transfer (WPT).

Wideband High-Gain Circularly Polarized Substrate Integrated Cavity Antenna Array for Millimeter-Wave Applications

A wideband high-gain circularly polarized (CP) substrate integrated cavity (SIC) antenna array is presented for millimeter-wave applications. The proposed antenna element is simply composed of a slot-coupled high-order-mode resonant square SIC and a pair of obliquely placed strip-shaped parasitic patches on the top surface of the SIC. The parasitic patches are used to adjust the aperture electromagnetic field distribution and phase of the two orthogonal resonant modes of TM211 and TM121 in the SIC to achieve a high-gain CP radiation and meanwhile introduce an additional cavity-backed slot-dipole CP radiation to extend axial ratio (AR) bandwidth of the proposed antenna element. By combining the above two high-gain CP radiation mechanisms, a wideband high-gain CP SIC antenna element is achieved. The simulated results of the proposed antenna element show an overlaid bandwidth of 20.36% from 26.20 to 32.14 GHz, while considering the −10 dB reflection coefficient, 3 dB AR, 3 dB gain bandwidths properties, and a maximum right-hand CP gain of 10.53 dBi at 29.40 GHz. On this basis, a wideband high-gain 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 8 CP array fed by a full-corporate substrate integrated waveguide (SIW) network is designed and fabricated. The measured results show that the proposed array has an overlaid bandwidth of 21.72% from 25.85 to 32.15 GHz and a measured gain of up to 26.10 dBic at 29.00 GHz.

Wideband low-RCS circularly polarized antenna with metasurface combining wave diffusion and polarization conversion

A novel and simple low-profile high-gain wideband circularly polarized (CP) slot antenna with low radar cross section (RCS) is presented. The proposed antenna is composed of a traditional linearly polarized (LP) slot antenna and an integrated metasurface-based superstrate. The superstrate consists of a center array with metasurface (MS) unit cells and four surrounding arrays with 4×4 MS unit cells. On the one hand, a wideband and high-gain CP radiation in the frequency band of 5.27-6.18 GHz (a relative bandwidth of 15.9%) is achieved by the polarization conversion property of the MS and four surrounding arrays. On the other hand, a broadband RCS reduction in the frequency band of 4.5-20 GHz (a relative bandwidth of 126.5%) is obtained by the combination of two electromagnetic wave diffusion principles. Inspired by C-band, X-band and Ku-band radar applications, a low-cost stealthy prototype with broadband low RCS and CP radiation is realized.

A Metasurface-Based Wide-Bandwidth and High-Gain Circularly Polarized Patch Antenna

A metasurface-based circularly polarized (CP) microstrip patch antenna with high performance in terms of the global bandwidth and gain is presented. The antenna configuration was a square-modified microstrip patch that was sandwiched between a metasurface and the ground plane. The metasurface comprised a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \times 4$ </tex-math></inline-formula> array of square patches, while the single-feed radiating microstrip patch had axial ratio (AR) tuning stubs and a crossed slot. Under excitation, the microstrip patch and crossed slot, in conjunction with the metasurface, generated multiple resonances and AR minimum points that combined to produce large global bandwidths with regard to the impedance, AR, and 3 dB gain. Using a stacked layout, a low-profile design with the dimensions of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$54\,\,\text {mm} \times 54\,\,\text {mm} \times 3.1$ </tex-math></inline-formula> mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.2\,\,\lambda _{\text {o}} \times 1.2\,\,\lambda _{\text {o}}\times 0.07\,\,\lambda _{\text {o}}$ </tex-math></inline-formula> at 6.8 GHz) was obtained, which generated a highly stable broadside gain above 10 dBic throughout the entire operating AR bandwidth. This antenna had a measured −10 dB impedance bandwidth of 5.62–11.04 GHz (65.06%) and a 3 dB AR bandwidth of 5.64–7.89 GHz (33.25%). In addition, it had a measured 3 dB gain bandwidth of 5.17–8.2 GHz (45.32%), with a measured peak gain of 12.17 dBic.

A Beam-Steering Solution With Highly Transmitting Hybrid Metasurfaces and Circularly Polarized High-Gain Radial-Line Slot Array Antennas

A continuous beam-steering solution for circularly polarized (CP) radial-line slot array (RLSA) antennas is presented and demonstrated with a fabricated prototype. The solution is based on the near-field meta-steering (NFMS) method, which is implemented through a pair of highly transmitting hybrid metasurfaces (HMs) that are placed above a high-gain CP RLSA antenna in the near-field region. Cells in HMs, unlike conventional metasurfaces (CMs), can provide exact or close to exact phase shift with transmission magnitude larger than −1 dB. This is achieved by combining the nonoverlapping phase ranges of two dramatically different phase-shifting cells. The RLSA is stationary, while the two HMs are rotated to steer the beam in a 2-D (azimuth and elevation) space. The measured results of the prototype demonstrate that the system can steer its beam to a maximum elevation angle of 40.6° with a maximum gain of 30.9 dBic. The axial ratio remained less than 3 dB in the 3 dB beamwidth even when the beam is steered. The height of the system is only 4.5 cm, which is much less than mechanically steered reflector antennas. Unlike electronically steered high-gain antenna arrays, this system requires only few watts of power only when rotating HMs and has zero power consumption when the beam is stationary.

A high‐gain circular polarization beam scanning transmit array antenna

A high-gain circular polarization (CP) beam scanning antenna based on planar transmit array (TA) is proposed. The planar TA is implemented using rectangular patches and square rings, and it has different frequency responses to two orthogonal polarized incident waves owing to different phase distributions in x- and y-direction. The TA can convert a linearly polarized spherical incident wave into a circularly polarized transmitted plane wave. In addition, beam scanning is achieved by in-plane translation of the feed antenna. The procedure is demonstrated for high-gain beam steering implementation operating in CP at the Ku-band. Full-wave simulation results demonstrate that the designed antenna enables elevation beam scanning from −33.6° to +33.6°, with a peak gain of 26.4 dBi. Scanning loss is better than 5 dB and the axis ratio remains below 3 dB for the entire scanning range in the frequency band of 13.9–14.9 GHz. Moreover, a prototype is fabricated and the measured results have good agreement with the simulated results, which confirms the feasibility of using this technology to achieve a high-gain, CP, low-cost and low cross-polarization beam scanning antenna.

High-Gain Circularly Polarized Array Antenna With Low Grating Lobe Property Based on TM30/TM03 Mode

In this letter, a high-gain circularly polarized (CP) array antenna with low profile and low grating lobe property is proposed. The array is composed of high-gain and low sidelobe CP patch elements based on odd high-order modes. By adding perturbation structure, a pair of orthogonal modes (TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</sub> /TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">03</sub> ) of the patch with 90° phase difference is diagonally excited. Meanwhile, by introducing five circular slots on the patch, four sidelobes of the element radiation pattern in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> o <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> plane and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> o <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> plane are effectively reduced. Consequently, the large grating lobes of array antenna can be avoided. Then, a 2 × 2 array prototype is designed and fabricated for verification. The thickness of array is only 0.5 mm (0.027 <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> ). The peak gain and aperture efficiency reach up to 17.5 dBic and 55.5%, respectively. When the element spacing is more than 1 <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> , the measured maximum grating lobe level at 16.25 GHz is only −15 dB.