Entire Impedance Bandwidth Research Articles

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 Compact Slotted UWB Antenna Based on Characteristics Mode Theory for Wireless Applications

The development of electronic systems and wireless communication has led to a proportional increase in data traffic over time. One potential solution for alleviating data congestion is to augment the bandwidth capacity. This study presents a novel asymmetric circular slotted semi-circle-shaped monopole antenna design using a defective ground structure. The extended ultrawide bandwidth is achieved by implementing a design where the semi-circle radiator is etched in a specific asymmetric circular slot. This involves etching a circle with a radius of 1.25 mm at the center of the radiator, as well as a succession of circles with a radius of 0.75 mm along the edges of the radiator. In addition, the ground plane is situated at a lower elevation and features a U-shaped truncation that has been etched onto its surface. The expansion of the impedance bandwidth can be accomplished by making adjustments to the radiator and ground plane. The UWB antenna under consideration possesses a geometric configuration of 21.6 × 20.8 × 1.6 mm3 and the antenna is fabricated using an FR-4 glass epoxy substrate. The UWB antenna operates throughout the frequency range of 2.2–16.5 GHz, exhibiting a gain of at least 3.45 dBi across the entire impedance bandwidth and the maximum peak gain of 9.57 dBi achieved at the mid-resonance frequency of 10.5 GHz. The investigation of the antenna’s physical properties is conducted utilizing characteristic mode analysis. The investigation also includes an analysis of the time-domain characteristics, revealing that the group delay was found to be less than 1 ns across the operational frequency range. The predicted and measured findings demonstrate consistency and confirm that the suggested antenna is suitable for electronic systems and wireless applications.

Compact and Broadband Loop-Loaded Dual-Mode Dipole Antenna

A compact and broadband dual-mode dipole antenna is proposed in this paper. Fundamental mode (f 1) is combined with third-order mode (f 3) to widen the bandwidth. To do so, f 3 is compressed/down-shifted close to f 1. This is realized by loading a loop at the current null points of f 3. Loop parameters are the crucial parameters for third-order mode compression and, thus, for wide bandwidth. The antenna was fabricated. Measurements were performed. Simulations and measurements are in good agreement. The prototype of the antenna has an electrical size of 0.33λL × 0.08λL at the lowest frequency of the operational band. The obtained frequency band for |S 11| ≤ −10 dB is 2.83 GHz–6.08 GHz which amounts to 73% bandwidth. The measured peak gain is 3.1 dBi. Stable omnidirectional radiation is obtained over the entire impedance bandwidth.

An Ultra-Compact 28 GHz Arc-Shaped Millimeter-Wave Antenna for 5G Application.

The 5th generation (5G) network was planned to provide a fast, stable, and future-proof mobile communication network to existing society. This research presents a highly compact arc shape structure antenna resonating at 28 GHz for prospective millimeter-wave purposes in the 5G frequency spectrum. The circular monopole antenna is designed with a radius of 1.3 mm. An elliptical slot on the radiating plane aids in achieving an enhanced bandwidth resonating at the frequency of 28 GHz. Including an elliptical slot creates new resonance and helps improve the bandwidth. The antenna has an ultra-compact dimension of 5 × 3 × 1.6 mm3, which corresponds to an electrical length of 0.46λ × 0.28λ × 0.14λ, where λ is free space wavelength at the resonant frequency. The projected antenna has an impedance bandwidth of 15.73 % (25.83-30.24 GHz). The antenna has a good radiation efficiency of 89%, and the average gain is almost 4 dB over the entire impedance bandwidth. The simulated and experimental S11 findings are in good agreement.

Third- and Fifth-Order Mode Compression of a Dipole Antenna

This communication proposes a novel tri-mode wideband dipole antenna with mode compression. Tri-mode operation and wide bandwidth (BW) are obtained by compressing the third- and fifth-order modes simultaneously and combining them with the first-order mode. The third-order mode is compressed using an elliptical loop formed by loading two identical semi-elliptical stubs at the current-null points of the third-order mode. The overlap area and size of the loop play a critical role to compress/shift the mode. Two symmetrical pairs of L-shaped stubs loaded at the second current-null points of the fifth-order mode compress the fifth mode. The amount of compression depends on the stubs’ length. The stub width and position affect the impedance matching. The proposed antenna has an operational BW from 2.75 to 7.43 GHz that equals to 91.9% BW. The peak gain and electrical size are 3.8 dBi and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.32\lambda _{L}\times 0.14\lambda _{L}$ </tex-math></inline-formula> , respectively. The radiation pattern is omnidirectional over the entire impedance BW. A prototype was developed, and the experiments were performed to validate the design concept and computational results. The experimental results are well within the range of the simulation results.

Two asymmetric cylindrical dielectric resonator loaded dual port multiple‐input multiple‐output antenna for wide band application with circular polarization attributes

SummaryA novel multiple‐input multiple‐output double asymmetrical cylindrical dielectric resonator antenna (MIMO‐DCDRA) with modified stub line feed is discussed and proposed in this work. Two unequal CDRA are placed diagonally to each other and are electromagnetically coupled with feeding arrangement via two asymmetrical circular apertures. By performing the optimization of the dimensional parameters, a significant impedance bandwidth of 70.84% ranging from 2.87 to 5.76 GHz and axial ratio bandwidth (ARBW) of 34.89% is obtained. Antenna gain is about 5.0 dBi within the operating frequency. The proposed MIMO‐DCDRA exhibits a low mutual coupling of (|S21| &amp; |S12| &lt; −20 dB) with the incorporation of a neutralization line. There are various diversity parameters that are also discussed in terms of mutual coupling, envelop correlation coefficient (ECC &lt; 0.002), diversity gain (DG &gt; 9.995), and channel capacity loss (CCL &lt; 0.3 bits/s/Hz) over the entire impedance bandwidth.

Gain Stabilization Method for Wideband Slot-Coupled Microstrip Antenna

Wideband slot-coupled microstrip antenna (SCMSA) is a distinctive electromagnetic wave radiator in recent years with wide bandwidth and low profile. In such a wide frequency range, the electrical distance, i.e., normalized to operating wavelength, between dual equivalent magnetic currents increases obviously with upward frequency. Therefore, the realized gain is usually with a large variation, which limits the wideband performance of SCMSA. In this communication, a feasible method is proposed to stabilize the realized gain of an SCMSA over its entire impedance bandwidth by utilizing a properly designed reflector-plus-sidewall structure (RPSS), which includes a reflector with an optimized height and two vertical sidewalls. Each part has its own function in realized gain compensation and enhancement, performing a flatter and higher realized gain in a wide frequency range. To validate this method, an antenna prototype is fabricated and tested. Compared with the referenced SCMSA, the measured results indicate that the proposed one adding RPSS maintains a wide impedance bandwidth of 24.8% (3.75–4.81 GHz), but reduces gain variation from 4.1 to 0.5 dB (10.5–11 dBi) with an average realized gain increment of 2.1 dB.

Proximity coupled fed wideband printed magneto–electric dipole antenna

Results are presented fora wideband printed magneto-electric dipole antenna. The printed electric dipole and reflector are separated by an air-gap and is fed with a coaxial transmission line and a printed proximity coupled T-shaped feeding strip. The slot between the electric dipole halves forms the magnetic dipole radiating aperture. This feeding mechanism allows for good impedance matching at adjacent resonances of the electric and magnetic dipoles to achieve wideband operation. The two printed electric dipole halves are DC shorted to the reflector. The results show that this antenna can operate over a wide bandwidth with good gain, stable unidirectional radiation patterns and low cross polarization. The effect of the air-gap height and the relative permittivity of the substrate on which the dipole is printed are investigated. Results show that an optimum air-gap height for a specific substrate permittivity can be determined that will result in a gain with a small variation over the entire impedance bandwidth of the antenna. Simulated as well as measured results are presented for a prototype antenna with a small gain variation and overall dimensions of 1.33λ0 × 1.33λ0 × 0.19λ0. A measured impedance bandwidth of 54% with an average gain of 9.2 dBi is achieved.

CPW-Fed Flexible Ultra-Wideband Antenna for IoT Applications.

In this article, an inkjet-printed circular-shaped monopole ultra-wideband (UWB) antenna with an inside-cut feed structure was implemented on a flexible polyethylene terephthalate (PET) substrate. The coplanar waveguide (CPW)-fed antenna was designed using ANSYS high-frequency structural simulator (HFSS), which operates at 3.04–10.70 GHz and 15.18–18 GHz (upper band) with a return loss < −10 dB and a VSWR < 2. The antenna, with the dimensions of 47 mm × 25 mm × 0.135 mm, exhibited omnidirectional radiation characteristics over the entire impedance bandwidth, with an average peak gain of 3.94 dBi. The simulated antenna structure was in good agreement with the experiment’s measured results under flat and bending conditions, making it conducive for flexible and wearable Internet of things (IoT) applications.

A Simple Compact Wideband Microstrip Antenna Consisting of Three Staggered Patches

This letter proposes a simple compact microstrip antenna with enhanced bandwidth. The antenna is composed of three narrow rectangular patches: one middle patch and two side patches. The side patches are staggered longitudinally with respect to the middle patch and connected using short strips. The antenna is printed on a thin single-layer dielectric substrate with a ground plane and fed by a coaxial probe at the center of the middle patch. By staggering the side patches with respect to the middle patch, two resonant modes are excited at two close frequencies and a wide bandwidth is obtained. The antenna has a compact size of 0.31 λ 0 × 0.29 λ 0 × 0.027 λ 0 (where λ 0 is the center operating wavelength in the free space) and a measured impedance bandwidth of 6.8% (return loss > 10 dB), which is approximately 2.3 times wider than that of a conventional square microstrip antenna on the same substrate. The antenna has a stable gain varying from 5.8 to 7.5 dBi and a low cross-polarization level less than −15 dB within the impedance bandwidth. The radiation characteristics are nearly constant over the entire impedance bandwidth.

Wideband Wide Beamwidth Full-Wavelength Sectorial Dipole Antenna Under Dual-Mode Resonance

In this article, a novel design approach to wide beamwidth dual-resonant, wideband sectorial dipole antennas is advanced. At first, a 1-D, full-wavelength dipole is evolved into a 2-D, sectorial dipole, so as to determine its two usable resonant modes. Then, both wideband and wide beamwidth characteristics are simultaneously attained under dual-mode resonance. Next, dual-resonant sectorial dipole antennas with flared angle of 270° and 240° are designed and studied. As experimentally validated, the proposed antenna exhibits an omnidirectional pattern with its impedance bandwidth over 70.4%. A few prototypes mounted above a ground plane are further investigated, so as to achieve a broad H-plane half-power beamwidth (HPBW) to over 120°. In addition, the antennas exhibit stable gain frequency response with fluctuation less than 2.2 dB within the entire impedance bandwidth. Thus, the advanced design approach based on 2-D dual-resonant, full- wavelength dipole leads to the formulation of novel wide beamwidth antennas with low frequency dispersion and simple configuration within a wide radiation bandwidth over 53.3%. Finally, a dual-polarized dipole antenna with port-to-port isolation higher than 34.5 dB and available radiation bandwidth of over 49% is implemented to further validate its potential for practical applications.

Wireless Body Area Networks: UWB Wearable Textile Antenna for Telemedicine and Mobile Health Systems.

A compact textile ultra-wideband (UWB) antenna with an electrical dimension of 0.24λo × 0.24λo × 0.009λo with microstrip line feed at lower edge and a frequency of operation of 2.96 GHz is proposed for UWB application. The analytical investigation using circuit theory concepts and the cavity model of the antenna is presented to validate the design. The main contribution of this paper is to propose a wearable antenna with wide impedance bandwidth of 118.68 % (2.96–11.6 GHz) applicable for UWB range of 3.1 to 10.6 GHz. The results present a maximum gain of 5.47 dBi at 7.3 GHz frequency. Moreover, this antenna exhibits Omni and quasi-Omni radiation patterns at various frequencies (4 GHz, 7 GHz and 10 GHz) for short-distance communication. The cutting notch and slot on the patch, and its effect on the antenna impedance to increase performance through current distribution is also presented. The time-domain characteristic of the proposed antenna is also discussed for the analysis of the pulse distortion phenomena. A constant group delay less than 1 ns is obtained over the entire operating impedance bandwidth (2.96–11.6 GHz) of the textile antenna in both situations, i.e., side by side and front to front. Linear phase consideration is also presented for both situations, as well as configurations of reception and transmission. An assessment of the effects of bending and humidity has been demonstrated by placing the antenna on the human body. The specific absorption rate (SAR) value was tested to show the radiation effect on the human body, and it was found that its impact on the human body SAR value is 1.68 W/kg, which indicates the safer limit to avoid radiation effects. Therefore, the proposed method is promising for telemedicine and mobile health systems.

Three-Stacked Dielectric Ring Resonator Loaded Hybrid Monopole Antenna for Improved Ultrawide Bandwidth

In this paper, a new wide-band and compact three-segment composite dielectric ring resonator (DRR) antenna excited by an axi-symmetric coaxial monopole has been introduced. The proposed antenna has been investigated numerically and experimentally for enhanced impedance bandwidth. At the lowest operating frequency, the presented antenna has a footprint area of just 0.16 x 0.16 . According to the measurement results, the antenna offers a fractional impedance bandwidth equal to 15 % with 8dBi peak gain. The antenna provides symmetrical and stable monopole like radiation pattern over the entire impedance bandwidth. With such performance, the suggested antenna can be usefully employed in different wide-band applications such as electromagnetic interference (EMI) and defense applications.

Multiple input multiple output dielectric resonator antenna with circular polarized adaptability for 5G applications

ABSTRACT In this paper, the concept of the circularly polarized agile, multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) structure for fifth generation (5G) new radio application in mobile terminal is presented. Two prototypes have been fabricated, namely one with cylindrical DRA (CDRA) referred as A1 and a second one with ring DRA (RDRA) named as A2. These practical realizations of dual-port MIMO antennas have been mounted on a Rogers 5870 substrate of octagonal shape with proper ground architecture. The proposed dual-port MIMO antennas have been excited with conformal probes and L-type feed network aiming to achieve circular polarization (CP). Measured impedance bandwidth of A1 and A2 are 21.2% (3.15–3.9 GHz) and 22.2% (3.12–3.9 GHz), respectively. Moreover, for both antennas low mutual coupling between ports with minimum isolation of dB over entire impedance bandwidth has been obtained by using triangular head slots in the ground plane. Measured axial ratio bandwidths in broadside direction are 5.66% (3.26–3.45 GHz) and 4.25% (3.45–3.6 GHz), respectively. Maximum gains are 7.3 and 7.2 dBi, in that order. MIMO antenna parameters such as envelope correction coefficient, diversity gain (DG), mean effective gain and total active reflection coefficient are also calculated to verify MIMO performance parameters. The proposed antennas also demonstrate CP agility with insertion of concentric cylindrical shells of different radii.

A Compact Flower‐Shaped Printed Monopole MIMO Antenna for Wideband Applications

AbstractThis paper presents a 2 × 1 flower‐shaped (FS) multiple‐input multiple‐output (MIMO) monopole antenna with enhanced bandwidth and compact dimensions for modern wireless wideband applications. The proposed FS‐MIMO antenna is formed by merging multiple ellipses, each of which has a different value of semimajor axis length and eccentricity. These ellipses are used to obtain resonances at different frequencies, which cumulatively give a wideband behavior. The antenna characteristics such as reflection coefficient (S11), peak gain, surface current distribution at different resonating frequencies, and 2‐D radiation patterns are investigated. The measured impedance bandwidth (for S11 below—10 dB) of the implemented antenna is around 126% (2.52–11.12 GHz). The measured peak gain varies from 2.16 to 6.57 dB in the entire impedance bandwidth. Furthermore, the measured values of diversity performance parameters such as envelope correlation coefficient, diversity gain, total active reflection coefficient, and mutual coupling (S21) are found within their acceptable limit. The more compact dimensions of 22 × 24 mm2 (or about 0.15λ0 × 0.16 λ0) as compared to the latest state‐of‐art along with the good diversity performance makes the proposed antenna a capable contender for antenna structures supporting wide impedance bandwidth wireless applications. The proposed antenna shows the good matching characteristics under various scenarios such as an extended ground plane, USB connector, and device housing (both vertical and horizontal).

A Low-Profile High-Gain and Wideband Log-Periodic Meandered Dipole Array Antenna with a Cascaded Multi-Section Artificial Magnetic Conductor Structure.

This paper presents a low-profile log-periodic meandered dipole array (LPMDA) antenna with wideband and high gain characteristics. The antenna consists of 14 dipole elements. For compactness, a meander line structure is applied to each dipole element to reduce its physical length. As a result, a compact and wideband LPMDA antenna is realized, exhibiting a wide impedance bandwidth of 1.04–5.22 GHz (ratio bandwidth of 5.02:1) for || < −10 dB. To enhance the antenna gain performance while maintaining the wideband behavior, the LPMDA antenna is integrated with a new design of an artificial magnetic conductor (AMC) structure. The designed AMC is realized by combining three AMC structures of different sizes to form a cascaded multi-section AMC structure, of which its overall operating bandwidth can continuously cover the entire impedance bandwidth of the LPMDA antenna. The proposed AMC-backed LPMDA antenna is experimentally verified and its measured −10 dB reflection bandwidth is found to be in the range of 0.84–5.15 GHz (6.13:1). At the main beam direction within the operating frequency bandwidth, the gain of the proposed AMC-backed LPMDA antenna ranges from 7.15–11.43 dBi, which is approximately 4 dBi higher than that of an LPMDA antenna without an AMC. Moreover, the proposed antenna has a low profile of only 0.138. ( is the free-space wavelength at the lowest operating frequency).

Wideband SIW-Based Low-Cost Multilayer Slot Antenna Array for $E$ -Band Applications

This paper proposes a substrate integrated waveguide (SIW) slot antenna array for the wideband gigabyte mobile radio application in the $E$ -band. The wideband unit cell design is based on simultaneous feeding of four-element radiation slots with a higher order cavity mode directly excited by a simple slot aperture fed by a microstrip fork-like tuning stub. Employing the higher order mode along with the slot aperture facilitates low loss, simple feeding network, and lower sensitivity to fabrication errors. To cancel the beam tilt versus frequency, the higher-order-mode unit cell is used in a $2 \times 2$ array along with a differential feeding structure. The array was designed and taped out using a new high-resolution multilayer printed circuit board (PCB) technology and characterized by using the constructed millimeter-wave (mm-wave) measurement setup at KU Leuven/imec. This technology provides the possibility to stack microvias in PCBs and reduces the fabrication cost compared to other multilayer technologies in mm-wave bands. The proposed array in $2 \times 2$ array configuration has a measured bandwidth of 11.4 GHz (16%), a total efficiency of 69%, a realized gain of 12 dBi at 72 GHz, and a 3-dB gain bandwidth that covers the entire impedance bandwidth. In comparison with existing $E$ -band SIW slot arrays (compensating for array sizes), the proposed design achieves similar or better performance in bandwidth but with lower cost, lower sensitivity to fabrication tolerances, and higher total efficiency.

Compact UWB-MIMO Antenna With High Isolation and Triple Band-Notched Characteristics

A novel and high-performance four-element ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna is proposed in the paper. The proposed antenna is designed by using a novel integration technology of the symmetric layout, orthogonal structure, four-directional staircase-shaped decoupling, and multi-slit and multi-slot techniques. The mutual couplings among the antenna elements are significantly reduced by introducing the symmetric orthogonal and separated four-directional staircase-shaped structure. Furthermore, the antenna size is effectively miniaturized, and its impedance bandwidth is broadened by using a two-sided symmetric layout, partial and defected ground structure, the decoupling structure, and multi-slot and multi-slit techniques. Therefore, the antenna has the low-profile structure and a small dimension of 39mm $\times 39$ mm $\times 1.6$ mm. Moreover, the proposed antenna achieves triple band-notched characteristics by embedding different type slots and slits on the square radiating elements, default ground structure, and the decoupling structure, respectively. As a result, the antenna obtains the wider bandwidth of 2.30–13.75 GHz with the notched bands of 3.25–3.75 GHz, 5.08–5.90 GHz, and 7.06–7.95 GHz. The three notched bands are good in agreement with the existing interference bands of WiMAX (3.3–3.7 GHz), WLAN (5.15–5.875 GHz), and ${X}$ -band (7.1–7.9 GHz), respectively. In addition, the proposed antenna also has a lower mutual coupling ( $\eta _{\mathrm {mux}}> -3.0$ dB), stable gain, and quasi-omnidirectional radiation patterns at the entire impedance bandwidth. Therefore, a good tradeoff of the performance is obtained for the proposed antenna. The proposed antenna can be a good candidate for UWB-MIMO wireless communication applications, and especially for portable UWB-MIMO systems.

A CPW-fed flexible UWB antenna for IoT applications

In order to keep pace with the growing research and development on flexible and reconfigurable electronics, this research presents an inkjet printed ultra-wideband (UWB) flexible antenna on photo paper. The antenna pattern comprises a circular patch with the double stepped symmetric ground plane and is fed by a coplanar waveguide (CPW) technique on one-sided photo paper. The system is designed, simulated, fabricated, and tested experimentally. It operates over 3.2–30 GHz (161% fractional bandwidth, FBW) range with a return loss of − 10 dB or less and a voltage standing wave ratio (VSWR) < 2. The proposed monopole antenna is of dimensions 33.1 mm × 32.7 mm × 0.254 mm with an electrical size of 0.35 λ × 0.35 λ at 3.2 GHz frequency. This design exhibits nearly omnidirectional radiation pattern over the entire impedance bandwidth. An average gain of 4.87 and a radiation efficiency of 86.61% was observed. The miniature size, higher operating range, relatively constant radiation pattern along with higher acceptable peak gain of the antenna on a paper substrate lend itself to wearable and Internet of Things (IoT) applications.

Circularly Polarized Split Ring Resonator Loaded Slot Antenna

A compact circularly polarized printed slot antenna operating at 2.45 GHz is reported. The antenna consists of a pair of rotated square split ring resonators (SRR) inside a rectangular slot etched on the ground plane of an FR-4 dielectric substrate. A microstrip open-loop feed is etched on the backside of the dielectric substrate to feed the slot and the split ring resonators. The overall size of the antenna is 60x42x1.6 mm3. The measured -10dB impedance bandwidth is 10.48% (2.38-2.64 GHz) and the measured 3dB axial ratio (AR) bandwidth covers the entire impedance bandwidth.