Wide Axial Ratio Bandwidth Research Articles

Compact Circularly Polarized Shared Aperture Antenna with Wide Axial Ratio Bandwidth for NavIC Receiver

A novel probe fed right hand circularly polarized (RHCP) shared aperture antenna with concentric configuration is designed for L5 and S-bands NavIC receiver application. The structure consists of a square loop-type patch antenna for the L5 band, serves as the top radiator, and a concentrically truncated corner patch antenna for the S-band is embedded in the non-radiating portion of the L5 band antenna. The square loop is orthogonally fed with electromagnetically coupled strips with equal power and quadrature phased shift through symmetric vias. These vias are connected to the feeding network, which consists of a Wilkinson power divider that is designed on opposite sides of the ground to mitigate spurious radiations. Furthermore, the S-band antenna, placed inside the L5 band substrate, achieves CP by corner truncation. This technique increases the aperture reuse efficiency and improves the isolation between both radiators. The overall profile of the antenna is 75×75×8mm3 and exhibits a wide impedance bandwidth of 25.5% for the L5 band and 6.5% for the S-band, with an isolation of better than 20dB for both bands. The axial ratio bandwidth achieved is 25.5% and 4.1% for the L5 and S bands, respectively, with boresight gain of 3.57 dBiC and 4.8 dBiC in the L5 band and S-band, respectively. The proposed antenna is based on a shared aperture technique, which has different feeding ports for both bands; thus, it improves the G/T performance and noise figure of the overall system. These characteristics make the proposed antenna suitable for use in NavIC application.

Microstrip Circularly-Polarized Leaky-Wave Antenna with Wide Axial Ratio Bandwidth for X-Band Application

Microstrip Circularly-Polarized Leaky-Wave Antenna with Wide Axial Ratio Bandwidth for X-Band Application

Machine learning validated compact circularly polarized dual port-MIMO antenna with polarization diversity for ku-band applications

A novel dual Port C-Shape MIMO broadband printed antenna with wide axial ratio bandwidth (ARBW) is modelled and built for Ku band Applications. The unit cell of the proposed antenna has a compact size of 25 × 26 × 0.8 mm3 engraved on RT duriod 5880 material (ε r = 2.2, thickness of 0.8 mm). The proposed model consists of C shaped radiator, plus symbol structure and a modified ground plane. The machine learning concept is used to investigate the dimensional dependency of the plus sign on the CP behaviour. The suggested antenna shows impedance bandwidth (−10 dB) and 3-dB ARBW of 6 GHz (12 GHz to 18 GHz) which is covering the whole Ku band. The diversity performance parameters and antenna parametric investigation is also carried out to justify the MIMO identity of the proposed design. The simulated and measured counterparts are found in harmony. The strength of the proposed antenna is its planar structure, wide ARBW, polarization diversity, and wide operating Ku bandwidth.

Tri-band antenna with metasurface-based ground plane for Sub-6 GHz 5G and 6G WPT applications

In this paper, a spiral-shaped metamaterial-loaded rhombic slotted microstrip patch antenna is investigated for Sub-6 GHz 5G and 6 GHz tri-band applications. A 1.524 mm thick Rogers RO4003 substrate (ϵr = 3.55, LosTanδ = 0.0027) opts for the antenna design. A partially grounded mechanism is implemented to control the operating frequencies of the antenna. A 5×5 triangular unit cell metasurface is deposited beside the partial ground plane to enhance the impedance bandwidth as well as to improve the impedance matching. A G-shaped metallic structure enclosed within the rhombic slotted antenna helps in creating circular polarization (CP) properties. The presented antenna resonates at 3.28 GHz (Mid-range Sub 6 GHz 5G band), 4.94 GHz (Upper range Sub 6 GHz 5G band), and 6.92 GHz (Sub 6 GHz 6G Band) frequencies. The maximum gain offered by the antenna is 8.81 dBi. Also, the developed antenna offers CP characteristics in all three operating bands with wide axial ratio (AR) bandwidth characteristics above 400 MHz in both the first and third operating bands. The radial characteristics of the proposed antenna show its capability of receiving EM signals from all directions as desired for a WPT system. For validation purposes, a prototype is fabricated and characterized as well.

Circularly Polarized 4 × 4 Array Antenna with a Wide Axial Ratio Bandwidth

In this manuscript, we propose a circularly polarized (CP) antenna design that can achieve broadband axial ratio (AR) bandwidth in the X-band. A sequentially rotated serial feeding network is applied to achieve the broadband requirement. The proposed antenna consists of two substrates, one is for feeding elements and the other is for radiating elements. The 16 radiating elements located on an upper substrate are fed through cross-shaped slots located in a ground plane between two substrates. The feed network is based on a 1:4 power divider design and consists of a serial connection of the power dividers resulting in the proper power splitting to the 16 radiating elements. The proposed antenna is designed to exhibit an optimal radiation characteristic of around 8.2 GHz with a CP antenna gain greater than 16 dB and similarly wide impedance and AR bandwidths. Experiments with the fabricated CP antenna were performed to support the proposed CP antenna design theory and are in good agreement with the simulation results.

Circularly polarized dielectric resonator based MIMO antenna for sub-6 GHz 5G cognitive radio applications

A 2-port wideband circular polarized (CP) multiple input multiple output (MIMO) dielectric resonator antenna (DRA) integrated with cognitive radio (CR) application is designed and investigated. This is a novel concept of integrating wideband CP-MIMO antenna based on dielectric resonator (DR), with CR concept. The multi-functional reconfigurable filter is designed within the feedline of the antenna making it applicable for both the operations of CR, namely, underlay and interweave. Rogers RT Duroid 5880 is used as the substrate for the designed CP-MIMO antenna. The antenna shows wide Axial Ratio (AR) bandwidth of 48.14% (2.2–3.50 GHz) and an overlapping bandwidth of 41.85% (2.37–3.50 GHz). The DR based MIMO antenna shows sensing range of 2.37–3.66 GHz. For the interweave operation, the designed CP-MIMO antenna shows narrowband frequency reconfigurability from 2.45–2.83 GHz. For the underlay case, the designed antenna shows band notch tunability between 3.23–3.62 GHz. The proposed antenna can be used effectively in sub-6 GHz band of the 5G communication systems.

Slots and stubs incorporated annular ring-shaped compact microstrip antenna with circular polarization characteristics for wireless UWB communication systems

A circularly polarized (CP) antenna with ultra-wideband resonance and a broad axial ratio bandwidth is designed for UWB communication systems. The prescribed design comprises of a modified annular ring-shaped radiator and a modified step-graded slots loaded partial ground plane. The projected antenna is prototyped on FR4 substrate of 35 × 30 × 1.6 mm3. To achieve wide axial ratio bandwidth, a rectangular vertical slot is inserted into the radiating patch and two stubs are embedded into the monopole ground plane, which is configured with step graded rectangular slots. The simulation results are verified by testing the fabricated protype. The proposed design operates at UWB spectrum with an ultra-wide impedance bandwidth (IBW) of 134.57%, centered at 10.7 GHz, covering 3.5 GHz to 17.9 GHz frequency spectrum. Furthermore, it demonstrates circular polarization characteristics with a broad axial ratio bandwidth (ARBW) of 96.29% expanding from 3.5–10 GHz (6500 MHz). Its peak gain reaches to 8.7 dBi and a maximum radiation efficiency of 95% is achieved within the operating band. The results (measured and simulated) obtained in terms of S11, axial ratio, gain and efficiency and radiation patterns exhibit high agreement. The presented antenna could be a suitable choice for 5.5 GHz Worldwide Interoperability for Microwave Access (Wi-Max), 5.2/5.8 GHz Wireless local area network (WLAN), X-band satellite communication (downlink: 7.25–7.745 GHz, uplink: 7.9–8.4 GHz), UWB communication systems, and other applications in microwave C, X, Ku bands due to its superior characteristics.

Omnidirectional circularly polarized base station antenna with high gain and wide band

Omnidirectional circularly polarized base station antenna with high gain and wide band

Circularly polarized implantable MIMO antenna for skin, brain and heart implantation with wide axial ratio bandwidth

SummaryA unique MIMO antenna with circular polarization characteristics that works similarly for skin, brain and heart phantoms has been proposed in this paper. The twin rectangular X‐shaped slot that serves as the basic structure of the proposed antenna is entirely planar and low‐profile but has a defective ground plane. For three different phantoms, the proposed antenna resonates at 2.4–2.45 GHz ISM band. With a dimension of , the antenna exhibits compactness. Rogers RT/duroid 6010 substrate material has been used to fabricate the antenna in order to validate the designed antenna structure. Utilizing the high dielectric material for both substrate and superstrate, both skin‐mimicking gel and minced hog meat were employed in the experiment setup at 2.45 GHz ISM band. At ISM band, −28.3 dBi has been observed has realized peak gain. The obtained fractional bandwidth (FBW) and Axial Ratio Bandwidth (ARBW) values are 30.67% and 45%, respectively. Also, the maximum specific absorption rate (SAR) values are found to be in the acceptable limit regulated by IEEE.

Bandwidth enhancement of circularly polarised slot global navigation satellite systems antenna using an integrated filter‐antenna approach

Abstract:A technique to enhance the bandwidth of a circularly polarised antenna using the filter‐antenna design approach is presented. The design relies on adding a resonator coupled to the radiation element—an L‐shaped slot antenna in the case of global navigation satellite systems. This change in the feeding structure broadens both the impedance and the axial ratio (AR) bandwidths and allows more design flexibility. Compared with a reference L‐shaped slot antenna with a conventional feed, the proposed antenna design achieves a doubling of the impedance matching bandwidth from 19% to 41% over the frequency range from 1.2 to 1.81 GHz and a wider AR bandwidth from 35% to 44.5% in the range from 1.17 to 1.84 GHz. The AR bandwidth covers the entire impedance bandwidth. The effect of a metal reflector on antenna performance is also investigated and discussed.

A 3D printed low‐profile wideband circularly polarised elliptical integrated lens antenna

AbstractThe authors presents a low‐profile wideband circularly polarised (CP) millimetre‐wave (mmWave) elliptical integrated lens antenna (ILA) fabricated by dielectric 3D printing technology. The proposed lens is integrated with a dielectric polariser and an air cavity for phase compensation, which can transfer incident waves from linearly polarised (LP) to planar CP waves over a wide bandwidth. Compared to the classic bifocal ILA, the proposed lens has a low profile. The phase compensation is performed by introducing a specifically shaped air cavity, which greatly reduces the length and weight of the lens. The polariser causes the two electric field components Ex and Ey to degenerate with an orthogonal phase difference, which results in the wideband characteristics of the antenna. The polariser, air cavity and lens can be conveniently and precisely fabricated by low‐cost 3D printing technology. Measurements show that the proposed ILA has a wide axial ratio (AR) bandwidth of 21.9–32.6 GHz, while the gain reaches 22.54 dBic with a 38% size reduction and a 60.7% weight reduction. Benefiting from the low profile, high gain, wide bandwidth and low cost, the proposed ILA has great potential to be the candidate antenna for 5G applications and satellite communications.

A Circularly Polarized Complementary Antenna with Substrate Integrated Coaxial Line Feed for X-Band Applications

This work presents a design for a complementary antenna with circular polarization that has a wide operating bandwidth, stable broadside radiation, and stable gain for X-band applications. The proposed antenna consists of an irregular loop and a parasitic electric dipole, which work together to produce equivalent radiation from the magnetic and electric dipoles. By arranging the dipole and the loop in a specific geometry, this antenna effectively generates circularly polarized wave propagation. A substrate integrated coaxial line (SICL) is applied to feed the antenna through an aperture cutting on the ground. The proposed antenna achieves a wide axial ratio (AR) and impedance bandwidths of 27.4% (from 8.5 to 11.22 GHz, for the AR ≤ 3 dB) and 39.6% (from 7.5 to 11.2 GHz, for the reflection coefficient ≤ −10 dB), respectively. Moreover, the antenna maintains a stable broadside radiation pattern across the operating bandwidth, with an average gain of 10 dBic. This proposed antenna design is competitive for X-band wireless communications.

A wideband X‐band circularly polarized printed monopole antenna backed by AMC reflector for 5G/IoT CubeSat applications

AbstractThis letter presents a coplanar waveguide‐fed printed monopole antenna backed by an artificial magnetic conductor (AMC) reflector. The proposed monopole antenna achieves circular polarization by loading the monopole with a printed coil and using an asymmetric ground plane. In addition, the AMC increases the antenna gain while maintaining a wide axial ratio (AR) bandwidth. The unit cell of the AMC is based on a Minkowski‐like prefractal geometry. The antenna is fabricated and measured with a total size of 1.07 λ0 × 1.07 λ0 × 0.25 λ0 at the operating frequency of 8.5 GHz. The measured results show a wide −10 dB impedance bandwidth of 26.9% (7.12–9.38 GHz), a wide 3 dB AR bandwidth of 22.23% (8–9.89 GHz) as well as a peak gain of 8.3 dBi at 8.5 GHz. This is significantly better than comparable antennas in addition to this design being the smallest in size.

A Wideband Differentially Fed Circularly Polarized Slotted Patch Antenna with a Large Beamwidth

A wideband differentially fed circularly polarized (CP) antenna featuring a slotted patch design with a large beamwidth is presented. The final design of the differentially fed CP antenna, aimed at achieving high gain and a wide axial ratio (AR) bandwidth, involves coupling a differential bending dipole antenna to the slotted patch in the same plane. The presented differentially fed CP antenna demonstrates characteristics of a large AR beamwidth, as verified by simulation and experiment. The measured AR beamwidths of 132.3° in the <i>xoz</i> plane (phi = 0°) and 116.2° in the <i>yoz</i> plane (phi = 90°) are realized at 5.5 GHz. The measured result exhibits broadband performance with a -10-dB impedance bandwidth of 78.8% (3.81–8.76 GHz), a 3-dB AR bandwidth of 36.7% (4.78–6.93 GHz), and a maximum gain of 10.2 dBic.

Substrate‐integrated‐waveguide cavity‐backed circularly polarized antenna with enhanced bandwidth and gain

AbstractWe propose a method for increasing the bandwidth of a substrate‐integrated‐waveguide (SIW) cavity‐backed antenna with taper‐based microstrip SIW transition feeding. For radio transmission, a circular slot is etched on top of the SIW cavity. For optimal antenna design, the slot is etched slightly away from the cavity center to generate circularly polarized waves. Simulations show a wide axial ratio bandwidth of 7.860% between 11.02 GHz and 11.806 GHz. Experimental results confirm a similar wide axial ratio bandwidth of 4.9% between 10.8 GHz and 11.35 GHz. An SIW feed from an inductive window excites the radiating circular slot, resulting in a simulated wide impedance range of 1.548 GHz (10.338 GHz–11.886 GHz) and bandwidth of 13.93%. Experimental results show a wide impedance of 2.08 GHz (10.2 GHz–12.08 GHz) and bandwidth of 18.84%. The SIW cavity‐backed antenna creates a unidirectional pattern, leading to gains of 6.61 dBi and 7.594 dBi in simulations and experiments, respectively. The proposed antenna was fabricated on a Rogers RT/Duroid 5880 substrate, and the reflection coefficient, radiation patterns, and gains were tested and compared using a computer simulator. The developed broadband antenna seems suitable for X‐band applications.

A Circularly Polarized Dielectric Discrete Lens Antenna With Wide Axial Ratio and Gain Bandwidths

This letter presents a novel circularly polarized (CP) discrete lens antenna, which exhibits wide axial ratio and gain bandwidths. It consists of a transmitting surface (TS) and a linearly polarized feeding source. For the former, it is based on a dielectric unit cell (UC) which is composed of two parallel slabs. This UC is anisotropic in its cross-section and variable in its height, which provide two degrees of freedom to manipulate the phase difference and the phase shifts of two orthogonal electric field components, and thus the TS can seamlessly attain linear to circular polarization conversion and collimated beam. In the design of the TS, 3-bit phase quantization is adopted. Owing to the non-dispersive characteristic of the UCs, the proposed TS shows superior bandwidth performance over the existing studies. For the latter, it is a commercial wideband double-ridged horn antenna which matches with the TS in terms of bandwidth. As a proof of concept, a 9×9 prototype is fabricated by using 3-D printing technology. Experimental results show that the proposed antenna has a 3-dB axial ratio bandwidth (ARBW) of 44.2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (8.8-13.8 GHz). The 1-dB and 3-dB gain bandwidths are 16.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (11.7-13.8 GHz) and 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (9.2-13.8 GHz), respectively.

A Compact Circularly Polarized Crossed Dipole Antenna with Wide Bandwidth using Split Ring Resonator and Parasitic Patches

A new compact broadband circularly polarized (CP) crossed dipole antenna using split ring resonator (SRR) and parasitic patches are presented. The proposed antenna is mainly composed of two orthogonal strip dipoles, two 90∘ phase delay lines, four SRRs, and four parasitic patches. The combination of the orthogonal strip dipoles and the delay lines forms a crossed dipole as the main CP radiator. The well-designed SRR can extend the current path and improve the current distribution of high-frequency without increasing the size of the antenna, thereby reducing the size of the antenna and increasing the axial ratio (AR) bandwidth of the high-frequency. The introduction of parasitic patches can improve the current distribution between the upper and lower cut-off frequency points of the bandwidth, and make up for the defects of the insufficient bandwidth of the crossed dipole and the SRR, thereby realizing broadband CP radiation. To verify the antenna, a physical prototype is fabricated. The measured results show that the impedance bandwidth (IBW) of 69.1% (1.38-2.84 GHz), and a wide AR bandwidth of 57.7% (1.43-2.59 GHz). In addition, the designed antenna achieves a stable gain in the working band and a certain band-edge selectivity. Such a single-fed, simple structure and the wideband CP antenna is an excellent candidate for communication systems such as ISM (2.4 GHz), WiBro (2.3-2.39 GHz)and Inmarsat.

A wideband low‐profile dual‐circularly polarized reflectarray with decoupled LHCP/RHCP beams

AbstractThis letter presents the design principle and experimental verification of a Ku‐band wideband low‐profile dual‐circularly polarized (dual‐CP) reflectarray (RA) with independent control of left‐/right‐handed circularly polarized (LHCP/RHCP) beams. Both the dynamic phase (DP) and Berry phase (BP) compensating methods are employed in the design of the unit cell, achieving independent LHCP/RHCP phase modulation based on the single‐functional‐layer concept. A single‐layer unit cell is designed, offering a ‐bit dual‐CP phase shift which facilitates the independent control of LHCP/RHCP beams. A prototype with asymmetrical dual‐CP beams is fabricated and tested. For LHCP and RHCP excitation, beam directions of () and () are realized, respectively, with sidelobe levels and cross‐polarizations both under −15 dB. The prototype exhibits a wide axial ratio (AR) bandwidth of over 36% with AR dB. The overlapped 1‐dB gain and AR dB bandwidth is 19.5% under LHCP input and 12.2% under RHCP input, with maximum aperture efficiency of 41.3% and 34.6%, respectively. The proposed dual‐CP RA exhibits broad band, pure chirality, high gain, low profile and independent polarization control, with single‐layer construction which is of low cost and easy processing.

A Dual-Circularly Polarized Wideband Dipole Antenna With Stable Axial-Ratio and Half-Power Beamwidths

With wide impedance bandwidth (IBW), wide axial-ratio bandwidth (ARBW), stable AR beamwidth, and stable half-power beamwidth (HPBW), a dual-circularly-polarized (DCP) crossed-dipole antenna is proposed. Each dipole consisting of two patches is fed by a pair of parallel transmission line, leading to a wide IBW. To enhance the ARBW and AR beamwidth, a quadrature wideband coupler is used, and the overlapping bandwidth of IBW and ARBW is up to 100%. The quadrature coupler is integrated with two pairs of parallel transmission line, and are printed on two substrates, which are squeezed into the space between the radiators and reflector, resulting into a compact antenna structure. With a total height of 0.016 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> , a prototype is fabricated and measured, showing 1.5-VSWR IBW of larger than 104% for both Left-handed CP (LHCP) and Right-handed CP (RHCP), 3-dB ARBW of up to 100% both for LHCP and RHCP, and port-to-port (polarization) isolation of lager than 30 dB in 1.70 - 2.82 GHz, so the effective bandwidth (EBW) is about 50% (1.70 - 2.82 GHz). 3-dB AR beamwidth of 76° ± 5°, stable DCP characteristics with average gain of 7.2 dBi and HPBWs of 67° ± 4° are achieved.

A Flat-Panel 8 × 8 Wideband K-/Ka-Band Dual Circularly Polarized Phased Array Antenna for CubeSat Communications

A novel flat-panel 8×8 wideband dual circularly polarized electronically-scanned phased array antenna is proposed, which covers the satellite communications bands of 22.55–23.55 GHz and 25.5–27.5 GHz. A circularly polarized stacked microstrip patch antenna is used as the element radiator with a structural modification on the parasitic patch to minimize gain variation. Since the axial ratio (AR) bandwidth of the element radiator is inherently narrow, sequential rotation is employed to yield a wide AR bandwidth while forming the 2×2 subarray, which is then used as a building block to construct the larger 8×8 phased array. The phased array has a simulated scan range of ±51°, ±46° and ±36° at 23 GHz, 24 GHz and 26.5 GHz, respectively, assuming ≤3-dB scan loss and AR. A beamforming network (BFN) is integrated within the stackup of the phased array that comprises a commercially available silicon beamforming chip. This facilitates beam steering through the independent control of the input amplitudes and phases of the individual element radiators. The practical effects of the BFN on the scanning performance of the 8×8 phased array is studied, which is found to slightly degrade the scan ranges. Finally, experiments were performed on the fabricated prototype, and the measured scan data showed good correspondence with their simulated counterparts with >41° and 35° scan ranges (in +θ direction) at 24 GHz and 26.5 GHz, respectively. The corresponding EIRp and G/T of the 8×8 phased array are also estimated through measurements.