Corner-truncated Square Research Articles

Circularly Polarized Variations of Truncated Corner Square Microstrip Antennas Employing a U-slot

Circularly Polarized Variations of Truncated Corner Square Microstrip Antennas Employing a U-slot

An inverted F-shaped slotted broadband metasurface-based circularly polarized patch antenna for 5G application

This paper presents an inverted F-shaped slotted broadband metasurface (MS)-based circularly polarized (CP) microstrip patch antenna. The host antenna comprises a truncated corner square patch with an inverted F-shaped slot, positioned on a 1.6 mm thick FR-4 substrate backed by ground plane. Concurrently, the MS layer is composed of a 4 × 4 square ring array, constructed on a separate 1.6 mm thick FR-4 substrate with net compact dimensions 0.54λo × 0.54λo × 0.027λo at 5.13 GHz, serving as a superstrate layer. The proposed antenna exhibits impressive performance, including a −10-dB impedance bandwidth from 4.40 GHz to 7.38 GHz as well as a 3-dB axial ratio (AR) bandwidth from 4.74 GHz to 5.52 GHz. Furthermore, at 5.13 GHz, it achieves a notable maximum radiation efficiency and realized gain of 85 % and 6.95 dBic respectively. Moreover, polarization of the antenna is observed as left-handed circularly polarized (LHCP). To validate the impedance response, the antenna’s equivalent circuit model has been sequentially developed, followed by the fabrication of a prototype. The measured results closely resemble with the simulated responses, indicating strong consistency between theory and experimental results. With its overall compact dimension of 0.65λo × 0.65λo × 0.027λo at 5.13 GHz, the proposed CP antenna is well-suited for 5G application.

Polarization independent highly insensitive ultra-wideband absorber for infrared, visible light and ultraviolet region

This work proposes a nickel-dielectric-nickel-based superwideband absorber for the infrared, visible, and ultraviolet spectrums. A square ring is loaded with a corner-truncated square patch to form the resonating structure. The absorber measures 25 × 25 × 10.6 nm3 in total. Absorption (A) is above 90 % throughout a frequency spectrum of 136.3564–5407.291 THz (55.48–2200.12 nm), with an average absorption of 96.49 %. Absorption is ≥95 % within the frequency range of 713.12–4684.15 THz (64.04–420.68 nm). The absorber has A ≥ 80 % for incident angle (θ) ≤ 50°. In the operational band, absorption averages 92.39 % at θ = 50° and 86.65 % at θ = 60°. This absorber has volume reduction upto 99.99 % (in terms of λL3, λL is wavelength at cutoff frequency for A ≥ 90 %), A ≥ 90 % ultrawide bandwidth of ∼190 % (for A ≥ 90 %), average A = 96.49 %, polarization insensitiveness, stable A ≥ 80 % for θ ≤ 50°, almost stable absorption performance for ±0.2 nm dimensions variations due to fabrication tolerances.

A single layered broadband circularly polarized MIMO antenna based on metasurface with aperture CPW feed

ABSTRACT In this paper, a single-layered broadband circularly polarized MIMO antenna is presented for a 5 GHz wireless local area network (WLAN). The Metasurface is designed with an array of patches and these patches are excited by four uniform aperture CPW feed MIMO antennas. The stubs are added across the aperture and central patches at respective apertures are increased to achieve broad bandwidth. Truncated corner square patches are used for the metasurface to achieve circular polarization (CP). The CP MIMO antenna has achieved an impedance bandwidth of 33% (4.35 GHz-6.08 GHz), a 3 dB axial ratio (AR) bandwidth of 11.95% (5.18 GHz-5.8 GHz) and a gain of 8dBi.

Circularly polarized truncated corner square slot antenna for Ku-band applications

The communication presents a novel microstrip line-fed compact square slot circular polarized antenna for Ku-band applications. The proposed square slot antenna with circular trimmed corners is fabricated on the FR-4 substrate with the defected ground on the opposite side of the patch. The axial ratio bandwidth (ARBW) is considerably enhanced by adding a shorting pin and the impedance bandwidth (IBW) is improved by etching pentagon- shaped slot in the defected ground. The antenna offers wide CP impedance bandwidth of 4.96GHz (13.6GHz-18.56GHz)) and simulated ARBW 4.85GHz (14.51-19.30GHz) and positive gain in the Ku-band. The presented antenna is appropriate for Ku-band applications.

Circularly Polarized MIMO Antenna Based on Microstrip Patch and Metasurface Structures

This paper shows a two-element multiple-input–multiple-output (MIMO) circularly polarized antenna. The proposed design achieves polarization diversity by using two conventional truncated corner square patches. Since the operating bandwidth of the conventional design is extremely narrow, a metasurface is utilized for bandwidth enhancement. In the open literature, several MS-based MIMO antennas have been reported. However, these designs can achieve high isolation with wide spacing between the MIMO elements. For the proposed design, the configuration of the MS is modified so that high isolation can be obtained with smaller element spacing. The design concept is verified by measurements on a fabricated prototype. The measured operating bandwidth (BW), which is an overlap between −10 dB impedance and 3-dB axial ration BWs, is from 5.0 to 5.6 GHz (11.3%). Across this band, the isolation is always higher than 20 dB and the realized gain is higher than 4.4 dBi.

A new wideband CP antenna with a single-layer metasurface

ABSTRACT In this paper, a new wideband circularly polarized (CP) antenna with a single-layer metasurface (MT) is developed. The single-layer MT consists of 4 × 4 truncated corner square patch cells with corner-cut square slots. Compared to the single truncated corner square patch, introducing corner-cut square slot can increase the design flexibility by changing the slot size for a wider CP operating bandwidth. A slit-shaped aperture coupling structure and a microstrip fed structure are placed together to provide coupling energy to the MT. Note that such MT and slot antenna share the same reference ground plane, and there is no air gap among the overall CP antenna structure. This design could easily make the profile low and the structure compact. The tested results reveal that the presented antenna features a broad 3-dB axial ratio bandwidth (18.2%, 5.25 ~ 6.3 GHz) and a wide −10-dB impedance bandwidth (19%, 5.25 ~ 6.35 GHz), which is very suitable for wireless communication systems with low-profile and wideband requirements.

Broadband and high gain circularly polarised truncated corner square patch metasurface antenna using aperture CPW feed

Broadband and the high gain circularly polarised antenna are designed in a single-layered planar substrate. An array of 3 × 3 truncated corner square patches are designed as a metasurface antenna on one side of the substrate and the metasurface antenna is fed by a stub-loaded uniform aperture CPW feed on another side of the substrate. In the metasurface antenna, the size of the central patch is increased for improving the bandwidth of impedance bandwidth and 3 dB axial ratio. Furthermore, the amount of truncation is reduced in the patches surrounding the central patch to enhance the bandwidth of impedance bandwidth and 3 dB axial ratio bandwidth. The designed metasurface antenna has achieved an impedance bandwidth of 38.2% (4.5–6.63 GHz) with an axial ratio bandwidth of 13% (5.0–5.7 GHz). Moreover, the antenna has a peak gain of 10.36dBic. The simulation and measurement results are compared.

A compact RHCP and LHCP truncated corner patch series-fed array antenna

ABSTRACT In this letter, a design of dual-circularly-polarised series-fed truncated corner patch antenna is proposed. This low-profile antenna consists of a 4 4 radiative truncated corner square shape array patches and two non-radiative substrate integrated waveguide (SIW) power-dividers. Moreover, using two perpendicular network feeds can help to generate right-hand and left-hand circular polarisations with two distinguished ports. The antenna operates with acceptable radiation characteristics in which the reflection coefficient is less than −10 dB from 11.7 to 12.2 GHz. Hence, the operating bandwidth of this antenna is about 500 MHz. To verify the simulated results, a prototype of this antenna is fabricated and measured. Simulation and measurement results prove that the proposed antenna can be a good candidate for satellite communication.

A mode‐combination‐based polarization‐reconfigurable antenna

In this article, a novel polarization-reconfigurable antenna based on the theory of linearly polarized (LP) modes combination is proposed. The antenna can electronically alter its polarization states between left-hand circular polarization, right-hand circular polarization and continuous linear polarization. A corner-truncated square patch with two isolated aperture-coupling feeds is used as the main radiator. By independently exciting the two feeding ports, the proposed antenna can work in two isolated orthogonal LP modes at 2.45 GHz, respectively. By simultaneously exciting the two feeding ports with different combination of amplitudes and phases, two circularly polarized (CP) modes and LP modes polarized at arbitrary azimuth can be obtained. The simulated and measured gains for all the polarization states are 7.3 dB at 2.5 GHz. The –10 dB impedance bandwidth ranging from 2.35 to 2.58 GHz is fully overlapped for all the polarization states.

High-Order Bandpass Polarization Rotator Based on Aperture-Coupled Patch Resonators

In this letter, a low-profile 90° polarization rotator with a fourth-order bandpass filtering response is proposed by using aperture-coupled patch resonators elements. The presented polarization rotator is constituted on a five-layer structure consists of two orthogonal rectangular apertures etched on two different layers, and are sandwiched between two single-mode square patch resonators and a dual-mode corner-truncated square patch resonator. Moreover, the property of 90° polarization rotation is obtained by properly exciting two orthogonal modes within the corner-truncated square patch resonator and the polarization selective characteristic of two orthogonal rectangular apertures. The proposed polarization rotator is designed and analyzed with the direct coupling matrix method. To validate the design concept, a design example is fabricated and measured. Measured results well reveal that our proposed structure has its attractive advantages of ultrathin profile, high-order filtering response, high polarization purity, and stable performance under oblique incidence.

Compact Four-Port Dual-Sense Circularly Polarized Stack-Up Patch Antenna for UHF/MW-RFID MIMO System

A four-port dual-band dual circularly polarized (CP) stack-up patch antenna is introduced for multiple-input-multiple-output (MIMO) RFID application. The proposed antenna adopts two FR 4 substrates and one Rogers Ro4350b substrates. Two pairs of isolated ports work at FCC UHF/MW-RFID bands (0.902–0.928 and 2.4–2.485 GHz) with port isolations of 20 dB and 25 dB, respectively. Four inverted-F radiating elements fed with a 90° phase-delay feeding network realize the CP radiation at the FCC UHF-RFID band (0.902–0.928 GHz). The corner-truncated square slot and patch are implemented to obtain CP modes at the MW-RFID band. The relative impedance bandwidths in the FCC UHF and MW band are 10.9% and 9.4%, respectively, with peak gains of 4.1 and 7.2 dBic. The antenna’s MIMO performance of envelope correlation coefficient (ECC) is lower than 0.01, and diversity gain (DG) is close to 10 dB. Thanks to the stack-up configuration, the dual-band RFID antenna realizes good antenna performance with a compact size of 0.6 × 0.6 × 0.07 λ3.

Compact Dual-Band Circularly Polarized Stacked Patch Antenna for Microwave-Radio-Frequency Identification Multiple-Input-Multiple-Output Application

A compact, low-profile, two-port dual-band circularly polarized (CP) stacked patch antenna for radio-frequency identification (RFID) multiple-input-multiple-output (MIMO) readers is proposed, which employs the shared-aperture technique. The proposed antenna adopts a 1.524 mm thickness Rogers Ro4350b substrate with relative permittivity of 3.48. Two pairs of isolated ports are working at two microwave- (MW-) RFID bands (2.4–2.485 GHz and 5.725–5.875 GHz) with high port isolation of 25 dB and 30 dB, respectively. A shared metal slot layer is designed to separate two feeding structures of the lower band and upper band for port isolation enhancement as well as saving space. Corner-truncated square slot and patch configurations have been designed to obtain CP modes. In the lower and upper MW-RFID bands, the relative impedance bandwidths are 12.2% and 5.7%, and the maximum realized gains are higher than 7.3 dBic. Moreover, two-element configurations have been combined for an RFID MIMO system that occupies a dimension of 119 mm × 119 mm × 12.9 mm. The MIMO antenna performance of envelope correlation coefficient (ECC) is lower than 0.03, and diversity gain is close to 10 dB.

A Broadband Low-RCS Metasurface for CP Patch Antennas

A novel metasurface (MS)-based method for broadband radar cross section (RCS) reduction of circularly polarized (CP) patch antennas is proposed. The RCS reduction is achieved in a much broader band than the operational band of the antenna. The simple technique is based on MS units on a grounded substrate in a checkerboard-like configuration. The broadband RCS reduction is achieved by combining two different destructive interference principles. In the high-frequency region, for a normal incident wave, the RCS is reduced by the phase cancellation generated by the MSs and the grounded substrate. In the low-frequency region, the RCS is reduced by the polarization conversion property of the MS. In this case, the fields reflected by two MS sections are in counter phase for a normal incident wave. The MS is combined with a CP patch antenna. It concerns a traditional corner-truncated square patch and four sequentially rotated surrounding MS cells. This dedicated MS allows two things: an additional resonant mode is excited resulting in a 3 dB AR bandwidth extension from 4.2% to 15.9% and a broadband RCS reduction of over 6 dB from 4.95 to 15.73 GHz (104.25% bandwidth) for both x- and y-polarized incident waves.

Ultra-wideband linear-to-circular polarization conversion metasurface**Project supported by the Natural Science Foundation of Shaanxi Province, China (Grant Nos. 2019JM-077 and 2018JM-6098), the Scientific Research Program Funded by Shaanxi Provincial Education Department (Grant No. 18JK1195), and the Shaanxi Key Research and Development Project, China (Grant No. 2019GY-055).

An ultra-wideband and high-efficiency reflective linear-to-circular polarization conversion metasurface is proposed. The proposed metasurface is composed of a square array of a corner-truncated square patch printed on grounded dielectric substrate and covered with a dielectric layer, which is an orthotropic anisotropic structure with a pair of mutually perpendicular symmetric axes u and v along the directions with the tilt angles of ±45° with respect to the vertical y axis. When the u- and v-polarized waves are incident on the proposed metasurface, the phase difference between the two reflection coefficients is close to –90° in an ultra-wide frequency band, so it can realize high-efficiency and ultra-wideband LTC polarization conversion under both x- and y-polarized incidences in this band. The proposed polarization conversion metasurface is simulated and measured. Both the simulated and measured results show that the axial ratio (AR) of the reflected wave is kept below 3 dB in the ultra-wide frequency band of 5.87 GHz–21.13 GHz, which is corresponding to a relative bandwidth of 113%; moreover, the polarization conversion rate (PCR) can be kept larger than 99% in a frequency range of 8.08 GHz–20.92 GHz.

Multi-State Reconfigurable Antenna for Wireless Communications

A compact frequency and polarization reconfigurable antenna is presented. The antenna comprises of a truncated corner square patch along with two strip lines running parallel to it. The entire model is fabricated on single layer roger RO 4350 substrate. Pin diodes are used for switching frequency and polarization states. Two ports are used for switching polarization states. The antenna can achieve two frequency bands and four polarization states. The antenna model is fabricated and the measured results are compared with simulated results. The antenna achieves − 10 dB impedance bandwidth of 100 MHz for LP state and 50 MHz for CP state and also the antenna attains good cross-polarization isolation of > 15 dB in all states. The antenna gives a maximum measured gain of 5.48 dBi for linear polarization (LP) state and 4.82 dBi for circular polarization (CP) state.

Dual‐band metasurface‐based CP low‐profile patch antenna with parasitic elements

A single-feed dual-band circularly polarised (CP) patch antenna is proposed. The antenna consists of a corner-truncated square patch antenna and a superstrate composed of a lattice of 2 × 2 metallic patches surrounded by parasitic elements. The driven patch generates one resonant mode. The metasurface with parasitic elements excites two additional resonant modes (TM10 and TM20). The combined resonances result in minimum axial ratio points, and a good dual-band CP operation is achieved. Simulations show that the antenna has a CP operating bandwidth of 40 MHz centred at 3.72 GHz (1.07%), and a CP operating bandwidth from 5.37 to 6.05 GHz (11.9%). The simulated gain is ∼7.05–7.1 dBic for the low-frequency band and 4.17–6.07 dBic for the high-frequency band, respectively. Measurements and simulations are in good agreement.

Low-profile wideband circularly polarized MIMO antenna with polarization diversity for WLAN applications

In this paper, a low-profile wideband circularly polarized (CP) multiple-input multiple-output (MIMO) antenna is presented for wireless local area network (WLAN) applications. The antenna is designed with the help of two truncated corner square patches and parasitic periodic metallic plates. A prototype of the proposed antenna is fabricated and measured. The measurements indicate that the proposed MIMO antenna has usable bandwidth of 13.7%. By properly designing the configuration of the metallic plates, high port isolation of better than 20 dB is achieved. In addition, the diversity performance in terms of envelop correlation coefficient (ECC) is also calculated, showing satisfactory MIMO characteristics. Finally, compared to the other reported CP MIMO antennas in literature, the proposed design possesses exclusive features including low profile structure and wide operating bandwidth.

Bandwidth‐enhancement of circularly‐polarized fabry‐perot antenna using single‐layer partially reflective surface

In this article, we investigate bandwidth-enhancement of a circularly-polarized (CP) Fabry-Perot antenna (FPA) using single-layer partially reflective surface (PRS). The FPA is composed of a single-feed truncated-corner square patch antenna, which is covered by the PRS formed by a square aperture array. We revealed that the finite-sized PRS produces extra resonances and CP radiations for the antenna system, which broadened the impedance matching and axial ratio (AR) bandwidths significantly. For verification, a broadband CP FPA prototype operating near 5.8 GHz was realized and tested. The fabricated antenna with overall size of 125 mm × 125 mm × 23.5 mm achieves a |S11| < −10 dB bandwidth of 31.7% (5.23-7.2 GHz), an AR < 3-dB bandwidth of 13.7% (5.45-6.25 GHz), the peak gain of 13.3 dBic, a 3-dB gain bandwidth of 22.38% (5.0-6.26 GHz), and a radiation efficiency of >91%.

A dual polarized multiband rectenna for RF energy harvesting

The paper presents a multiband dual polarized rectenna for RF energy harvesting in C-band application range. The receiving antenna of the designed rectenna is consisting of a truncated corner square patch loaded with several circular slots, L-slots and U-slot. A proximity coupled feeding arrangement is used for obtaining a wide impedance bandwidth so that the complete C-band from 4 to 8 GHz can be covered. The proposed antenna has the advantage of compact size and dual polarization since circular polarization is realized at three bands (5.42 GHz, 6.9 GHz and 7.61 GHz) in the −10 dB impedance bandwidth range. For efficient RF to DC conversion a two-stage voltage doubler rectifier is used considering that it provides a higher voltage multiplication with a small threshold voltage at its primary stage. For ensuring maximum RF to DC conversion efficiency; a matching network has been designed and is connected in between receiving antenna and the rectifier circuitry in order to match the antenna and load in different frequency bands. It is observed that a maximum conversion efficiency of 84% is achieved at 5.76 GHz. The proposed rectenna has been fabricated and it is found that measured results are in good match with the simulated results.