Axial Ratio Bandwidth Research Articles

Circularly polarized dual-band resonance in a miniaturized implantable antenna using combined hexagonal and rhombic patches

The design and characterisation of a novel dual-band implantable antenna with compact size is presented in this research. The antenna, which is in size and operates at two critical frequencies—0.954 GHz in the UHF band and 2.4 GHz in the ISM band—was fabricated on an RT6010 substrate. The U-shaped slot and shorting pin on the radiating element have been exploited to achieved dual-band and circular polarization. The antenna is noteworthy for achieving circular polarization with a broad axial ratio bandwidth of 24.6%, which enables strong performance throughout its operating frequencies. The proposed antennas SAR values satisfy IEEE safety standards for implantable medical devices with a gain of − 28.1 dB at 2.4 GHz and − 31.2 dB at 0.954 GHz, despite its small size. The design represents a significant advancement in the field of medical implant technology since it prioritizes effective wireless communication capabilities while upholding strict safety regulations.

Topologically Streamlined Single Feed Wide Band Circular Polarized Antenna

A single feed circularly polarized (CP) microstrip hexagonal open loop monopole antenna with defective ground plane is introduced in this article. The antenna is made up of an open hexagonal loop excited by a 50Ω microstrip feed line, ground defected by a curved structure with two slots and a “U” shaped slit etched below the microstrip feed line. The optimized designs are verified experimentally for reflection coefficient, axial ratio bandwidth, realized gain and radiation patterns. Results of the measurement indicate that the proposed antenna attains a wide impedance bandwidth of 103% (2.5–7.8 GHz), axial ratio bandwidth of 83% (2.9–7 GHz) and peak gain of 3.5 dBi. The proposed radiator’s novelty stems from the blend of uncomplicated geometry and single-point-fed excitation with broadband CP characteristics having a compact size of only 0.149λ0 at the lowest CP frequency. The suggested antenna is an appropriate one for various wireless communication applications like WLAN, Wi-MAX, Aeronautical Radio Navigation band and C band applications. Exhaustive studies indicate superior performance of the suggested antenna as compared with the state-of-the art designs.

A wide band circularly polarized antenna using meta surface for Wi-Fi applications

Abstract A circularly polarized, single-feed, low-profile patch antenna with enhanced gain and bandwidth for WI –FI applications is presented in this paper. The proposed antenna has a slot-loaded square patch (SLSP) is placed between reactive impedance structure (RIS)-based metasurface (MS) and the ground plane. A 6x6 circular RIS metasurface is used to improve the gain, impedance and axial ratio bandwidth. The antenna prototype’s overall dimensions are 60mm x 60mm x 3.6mm.The measured impedance bandwidth (IBW) of the proposed antenna is 26% (4.98GHz–6.48GHz) which covers the 5GHz (5.150-5.850 GHz) and 6GHz (5.950 – 7.125 GHz) frequency bands of wireless spectrum. The antenna exhibits right hand circular polarization with maximum measured gain of 6.5 dBic and the 3-dB ARBW is 5.23% (5.47GHz–5.77GHz).

Dual circularly polarized dual-band antenna combining transmitarray and reflectarray for K/Ka-band uplink and downlink satellite communication

This paper presents a dual-band antenna system utilizing transmitarray (TA) and reflectarray (RA) having dual-circularly polarized (CP) characteristics for K/Ka-band satellite communication. The antenna consists of the TA and RA surfaces operating at 19.5 GHz and 29.7 GHz respectively. The RA is designed on a single substrate layer with element size of 0.30 λ × 0.30 λ (λ corresponding to 30 GHz), whereas the TA is designed on two substrate layers with element size of 0.33 λ × 0.33 λ (λ corresponding to 20 GHz). The equivalent circuit model (ECM) of the TA and RA elements is extracted to validate the working of the proposed elements. A small window of the size of a patch antenna is cut in both the RA and TA surfaces to accommodate the coaxially-fed illuminating sources. The antenna shows the peak gain of 17 dBiC at 19.5 and 29.7 GHz. The 3 dB axial ratio bandwidths range from 19.3–19.6 GHz (1.55 % ) and 29.5–29.9 GHz (1.35 % ) in the two frequency bands. The antenna radiates two orthogonally polarized CP waves at two frequency bands which makes the antenna suitable for satellite communication applications.

Wideband Circularly Polarized Conformal Dielectric Resonator Antenna for High Gain Applications

ABSTRACTA compact and circularly polarized convex dielectric resonator antenna (CDRA) is investigated in this communication. Eigenmode method is used to analyze electromagnetic field propagation and resonant frequency of the antenna. Benefits of conformal structure over a planar surface are mentioned. A pair of vertical slots are introduced on the ground plane to produce orthogonal degenerate modes. Finally, the proposed curved DRA provides a fractional impedance bandwidth of 22%, axial ratio bandwidth of 11.27% and a stable gain of more than 5 dBi over the desired passband with a peak gain of 7 dBi. To validate the simulated results, a prototype is fabricated and measured.

A Compact Broadband Common-Aperture Dual-Polarized Antenna for Drone Applications.

A novel common-aperture miniaturized antenna with wideband and dual-polarized characteristics is proposed, which consists of a circularly polarized (CP) and a linearly polarized (LP) antenna. The circularly polarized antenna stacked on the upper layer adopts asymmetrical ground and introduces the patch and T-type feed network. On this basis, the meshed reflector structure, which also works as a ground plane for the LP antenna, is added to reduce the influence on circular polarization and achieve directional radiation. The LP antenna stacked in the lower layer uses a monopole structure, and the coaxial feed line perforates the reflector, and thereby the common-aperture antennas are tightly stacked together from top to bottom. Simulation and test are in good accordance, and the results show that the two ports of the antenna are well matched in the range of 5.5 GHz to 7.8 GHz, where peak gains of 8.5 dB and 6 dB are realized for circular polarization and linear polarization, respectively. Moreover, the 3 dB axial ratio (AR) bandwidth of the CP antenna is 34.3% and the isolation between the two ports is better than 15 dB, suggesting potential applications in the relay platform or drone detection for signal transmission and reception.

Design of polarization reconfigurable Koch fractal antenna for S-and C-band applications

Abstract In this research, a novel polarization reconfigurable fractal antenna with high gain is proposed for wideband applications. This antenna consists of a Koch curve based hexagonal ring patch, two Positive-Intrinsic-Negative (PIN) diodes, and partial ground. The patch is positioned on a Rogers RT/Duroid 5880 substrate (ϵr = 2.2) with overall dimensions 33 × 30 × 1.6 mm3. It has three frequency bands with three different cases i.e., case I, 3–7.91 (90%); case II, 3–7.73 (88.16%); and case III, 3.54–6.7 GHz (61.7%). As a result, the proposed antenna’s impedance bandwidth (IBW) offers constant wideband coverage ranging from 3–7.91 GHz (90%). The axial ratio bandwidth (ARBW) is below 3 dB over 3.6–6.9 (62.86%) and 3.33–7.14 GHz (72.78%) for LHCP (Case I) and RHCP modes (Case II), respectively. The value for LP mode (Case III) is 3.54–6.7 GHz (61.7%). A peak realized gains of 4.75, 5.07, and 3.8 dBi are achieved at 6.2, 6.3, and 6 GHz for Case I, Case II, and Case III, respectively. Both linear and circular polarization prototype was developed and the performance was verified through measurements. The design confirms good polarization-reconfigurable characteristics within the band of 3.91 – 7.91 GHz.

High-Performance CP Magneto-Electric Dipole Antenna Fed by Printed Ridge Gap Waveguide at Millimeter-Wave.

This paper presents a high-performance circularly polarized (CP) magneto-electric (ME) dipole antenna optimized for wideband millimeter-wave (mm-wave) frequencies, specifically targeting advancements in 5G and 6G technologies. The CP antenna is excited through a transverse slot in a printed ridge gap waveguide (PRGW), which operates in a quasi-transverse electromagnetic (Q-TEM) mode. Fabricated on Rogers RT 3003 substrate, selected for its low-loss and cost-effective properties at high frequencies, the design significantly enhances both impedance and axial ratio (AR) bandwidths. The antenna achieves an impressive impedance bandwidth of 31% (25.24-34.50 GHz) and an AR bandwidth of 24.9% (26.40-33.91 GHz), with a peak gain of up to 8.4 dBic, demonstrating a high cross-polarization level. The experimental results validate the high-performance characteristics of the antenna, making it a robust candidate for next-generation wireless communication systems requiring CP capabilities.

Compact triple-band ring-shaped printed antenna with circular polarization

This research proposed a planar printed antenna with circularly polarized (CP) ability. The antenna can supply an impedance bandwidth (│S11│<−10 dB) of 60% (2.3–4.3 GHz), 32.4% (4.8–6.8 GHz), 5.5% (7–7.4 GHz), and 24.4% (8.6–11 GHz) in the operative frequency band. The designed antenna has a 3 dB polarization axial ratio (AR) bandwidth (BW) of 88% (1.4–3.6 GHz), 11.3% (5–5.6 GHz), and 1.15% (8.6–8.7 GHz). The patch antenna dimensions are 20mm × 20 mm. To enhance AR bandwidth, an inverted L-formed strip line is added to the radiator to generate two electric fields with 900 phase differences. The measurement maximum gain of this patch antenna is about 7 dBi from 2.5 to 4.4 GHz. This structure has a wide AR beam width from – 30° to +110° at 2.4 GHz, – 70° to +70° at 5.2 GHz, and – 60° to +20° at 8.65 GHz. The CP antenna exhibits a miniaturized size and low-cost structure with suitable CP radiation characteristics.

A Novel Metasurface Antenna With Enhanced CP Bandwidth Through Decreasing Q Factor

ABSTRACTThis letter presents a novel metasurface antenna with improved axial ratio bandwidth using parasitic annular sector strips which decreased the Q factor. First, a metasurface antenna composed of a circular patch with etched annular cracks was designed and analyzed through characteristic analysis. Later, to enhance the axial bandwidth, four annular sector parasitic strips were added to decrease the Q factor based on transmission line analysis. In the end, the proposed antenna is fabricated and measured. The results show that the proposed antenna operates in the frequency band from 8.77 to 9.68 GHz; its 3 dB axial ratio bandwidth is 9.19–9.62 GHz, which is significantly improved by 119% compared to the case without the parasitic strips; the maximum gain is 7.2 dBic, which makes it a good candidate for marine search and rescue communications.

Design of Electrically Small Intraocular Antenna for Retinal Prosthesis System and Its Validation.

This paper presents an ultra-miniaturized circular-shaped triple band microstrip antenna as an intraocular unit applicable for retinal prosthesis. The reported antenna is developed by modifying a conventional circular-shaped patch with a pair of open-ended circular annular rings and a semicircular ring-loaded rectangular stub. Additionally, a shorting pin is used at the periphery of the patch to achieve the frequency bands of interest. Further, to make the structure electrically small and accommodate highly dense electrodes, the circular ground plane is modified by making symmetrical slots over the four quadrants and edges. Specific absorption rate distribution for 1g and 10g of different tissue layers over three operating frequencies has been studied by placing electromagnetic sources at different locations. With these arrangements, the proposed strip antenna offers multiband operation within the frequency band of 1.25 GHz (1.13-1.46 GHz), 2.45 GHz (2.24-2.66 GHz), and 3.32 GHz (3.09-3.50 GHz). Besides, circularly polarized radiation has also been achieved at 1.25 GHz with a 3-dB axial ratio bandwidth of 10 MHz. Finally, the proposed antenna structure is fabricated, and its measured performance metrics are in close aggreement with the simulated parameters. The proposed antenna's performance inside a customized canonical eye model (DMCM) and anthropomorphic Zubal head model is studied and compared with the prior studies.

Circularly Polarized Wideband Quad-Element MIMO Antenna With Improved Axial Ratio Bandwidth and Mutual Coupling

Circularly Polarized Wideband Quad-Element MIMO Antenna With Improved Axial Ratio Bandwidth and Mutual Coupling

A wideband circularly polarized filtering dielectric resonator antenna array based on magneto-electric currents combination

ABSTRACT A circularly polarized (CP) filtering dielectric resonator antenna (DRA) array is proposed based on the magneto-electric currents combination (MECC) method in this paper. The array consists of four rectangular DRAs, four hook-shaped electric dipoles (HSED), and two layers of substrate integrated waveguide (SIW) cavities. The electric current (EC) on the HSED is excited by the slot aperture of the SIW cavity, and the equivalent magnetic current (MC) is simultaneously generated with HSED in the DRA. Based on the surface current regulation, the EC and MC are adjusted to achieve appropriate amplitudes and phases, thereby realizing wideband CP radiation. The filtering function is realized with the high-pass characteristics of the SIW and the effective suppression of the higher-order modes in the resonance cavity. Due to the presence of an air gap between the DRAs and HSED, the higher modes of the DRA are designed for bandwidth enhancement. The prototype of the DRA array has been fabricated and measured, exhibiting a relative bandwidth of 26.1% and an axial ratio bandwidth of 17.77%, with radiation nulls present at either side of the passband. With the advantages of wide bandwidth and high gain, the proposed DRA array can be applied to satellite communications.

A closely spaced dual-band dual-sense linear-to-circular polarization converter for X-band applications

This paper presents a novel design of closely spaced dual-band dual-sense linear-to-circular polarization converting metasurface for X-band applications. The unit cell of the metasurface consists of a pair of L-shaped dipoles and a pair of cross-dipoles, respectively, with diagonal symmetry. The proposed linear-to-circular polarization converter (LCPC) provides a 3-dB axial ratio bandwidth (ARBW) ranging from 7.84 to 9.08 GHz (14.65%) for the lower band, and from 10.89 to 12.94 GHz (17.11%) for the upper band. The two frequency bands are in close proximity to each other, with a calculated separation bandwidth of 33.95%. Moreover, the proposed metasurface provides dual-sense operation, enabling polarization conversion to left-hand circular polarization (LHCP) in the lower band and right-hand circular polarization (RHCP) in the upper band for a y-polarized incidence wave and vice versa for an x-polarized incidence wave, respectively. These characteristics hold significant importance in different applications, such as satellite communication, that demand polarization diversity. After numerical analysis based on full-wave simulations, the proposed converter is fabricated and measured. A good agreement is observed between the full-wave simulated and measurement results.

Scalp-Implanted Ultra-Wideband Circularly Polarized MIMO Antenna for Biotelemetry Systems.

This paper presents an innovative, compact, dual-element, implantable, ultra-wideband, circularly polarized multiple-input multiple-output (MIMO) antenna designed to operate within the 2.45 GHz industrial, scientific, and medical band, and both of its radiating units are circularly polarized antennas with polarization diversity. Specifically, antenna-1 exhibits left-handed circular polarization properties, while antenna-2 demonstrates right-handed circular polarization properties. The slots in the radiating patch and ground plane help the antenna achieve 690 MHz (2.14-2.83 GHz) ultra-wide bandwidth characteristics and circularly polarized characteristics. Additionally, a slit connecting two U-slots on the ground plane allows the antenna to achieve a wide effective circularly polarized axial ratio bandwidth of 400 MHz (2.23-2.63 GHz). The antenna is compact, with dimensions of 0.065 × 0.057 × 0.0042 λ03 (λ0 represents the free-space wavelength corresponding to the lowest operating frequency). The proposed antenna system's performance was evaluated with a seven-layer homogeneous human head model, a real human head model, and minced pork. This evaluation revealed that the antenna attained a peak gain of -24.1 dBi and an isolation level of 27.5 dB. Furthermore, the assessment included the antenna's link margin (LM), key MIMO channel characteristics, and Specific Absorption Rate (SAR) metrics. The results indicate that the antenna performs exceptionally well.

Compact UWB Slot Antenna With Dual‐Circular Polarization and Improvement of CP Performance

ABSTRACTThis study presents an ultrawideband (UWB) slot antenna with a dual‐circular (left‐ and right‐hand) circular polarization. The presented circularly polarized (CP) antenna involves 45° oriented patches cooperating with I‐ and L‐shaped stubs fed by a directional coupler. Using a directional coupler produces orthogonal electric fields to generate CP operation, and as a result of the cooperation between patches and stubs, antenna CP performance is improved. The fabricated antenna, including two microstrip ports, occupies an area of 50 × 50 × 1.016 mm3. By stimulating each antenna port independently, it is possible to obtain right‐hand circular polarization (RHCP) and left‐hand circular polarization (LHCP). The experiments show that the antenna being presented has an operating frequency of 116.14% (2.87–10.82 GHz) and an axial ratio bandwidth of 33.97% (7.11–10.02 GHz). Furthermore, a stable radiation pattern was also measured for the antenna, which had a maximum gain of 2.77 dBic in the operating frequency band.

A compact broadband circularly polarized monopulse slot array antenna based on gap waveguide technology

ABSTRACT This paper presents a circularly polarized (CP) monopulse slot array antenna based on gap waveguide (GWG) technology. The proposed monopulse antenna is composed of a 4 × 4 array antenna fed by the monopulse comparator network in a compact three-layer structure. To achieve a broad axial ratio (AR) bandwidth of right-handed circular polarization (RHCP) in the sum radiation pattern, a septum polarizer is used in the radiating aperture. Based on this approach, horizontal transition structures are used to excite the radiating array from the WR-28 waveguide to the GWG, which helps to reduce the reflection loss and expand the impedance bandwidth. Experimental results show that the impedance bandwidth is 30.5 GHz to 40 GHz, which is 27.1%. The 3 dB AR bandwidth is 31%. The measured null depth is −40 dB, and the maximum measured gain in the sum pattern is 22 dBi at 34 GHz, while the antenna efficiency is greater than 86%. The advantages of low loss, broad bandwidth, and compact structure make the proposed antenna a competitive candidate for millimeter-wave (mmWave) monopulse direction-finding applications.

A wideband circularly-polarized MIMO filtering array antenna using dual-layer circular patch

ABSTRACT A novel wideband circularly-polarized (CP) MIMO filtering array antenna with dual-layer circular cross-slotted patch is introduced. The presented element consists of a two-way feeding structure designed with equal amplitude and 90° phase difference, and a dual-layer circular cross-slotted patch structure. An aperture-couple-driven patch is positioned between a cross-slotted patch and a dual-feed structure. It facilitates magnetic coupling to achieve a high-frequency resonant mode and radiation null. Meanwhile, four arc-shaped patches are electrically coupled to the driver patch by surrounding it with four shorting vias to improve the bandwidth. In multiple-input multiple-output (MIMO) wireless systems, a two-port MIMO dual-CP filtering array antenna for the Sub-6 G band is proposed. The design utilizes four proposed CP antenna elements and a dual-port transmission structure. The dual-port transmission structure consists of two sets of T-junction power dividers that are 180° phase shifted with opposite polarization. The dual-CP MIMO filtering array antenna of the impedance bandwidth is 21.8% (3.1 ~ 3.9 GHz). The AR bandwidth is 13.1% (3.3 ~ 3.7 GHz), while the gain bandwidth is 20.1%. Additionally, the isolation between the antenna elements is less than −15.0 dB. The envelope correlation coefficient between its two ports is less than 0.02.

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

Circularly polarized designs of square microstrip antennas employing U-slot are presented in a 2400 MHz frequency spectrum. Design with a U-slot employing unequal lengths or the corner truncated patch with equal length U-slot yields axial ratio bandwidths of 3.84% and 2.2%, respectively. Against the conventional offset feed patches or the truncated corner square patches, the proposed designs decrease the frequency and patch size by 10% and 22%, respectively. Reduction in the frequency and patch area, while employing the U-slot is not being discussed in the reported papers on the circularly polarized designs, and hence it is the new contribution in the present study. The U-slot cut configurations exhibit a radiation pattern in the broadside with a gain of larger than 6 dBi across the complete reflection coefficient bandwidth. To obtain a wideband and circular polarized response using a single patch, a reconfigurable design of a corner truncated square patch employed with a U-slot is presented. A design methodology is presented based on the resonant length formulation to obtain reconfigurable U-slot cut design as per specific band start frequency in wideband response or center frequency in the axial ratio bandwidth in the circular polarized antenna. This helps to design these configurations for the specific frequency band. Simulated results in the proposed design are verified using the measurements that reflect a close agreement.

Horizontally stacked inverted U-shaped dual-band implantable antenna with circularly polarized for biotelemetry application

Abstract A horizontally stacked inverted U-shaped dual-band implantable antenna is proposed for RFID and health care monitoring implantable applications. The designed antenna operates at 0.952 GHz ultrahigh frequency band (UHF; 0.951–0.956 GHz) and 2.4 GHz industrial, scientific, and medical band (ISM; 2.4–2.4835 GHz) in a suitable feeding scheme. The shorting pin is used on the radiation patch to minimize the antenna structure. The final dimension of the designed antenna size is 9 × 9 × 0.635 mm 3 . The defected ground structure (DGS) helped to produce radiation with circular polarization (CP) at 2.4 GHz resonant frequency. The designed antenna achieves an axial ratio (AR) bandwidth of 20% at 2.4 GHz resonant frequency. The antenna is designed on Rogers RT Duroid 6010 substrate and fabricated. The same dielectric material was used as a superstrate. At both the UHF and ISM frequency bands, the experiment was conducted using skin-mimicking gel and minced pork. The horizontally stacked inverted U-shaped antenna has a high peak gain of −27.5 dBi at 0.952 GHz. The computed maximum specific absorption ratio is within allowable bounds and complies with IEEE safety criteria.