Wide Impedance Bandwidth Research Articles

A Compact X and Ku Band Quad Port MIMO Antenna with Path Loss aModel for Urban Macro and Micro Environments

The prospective of multiple-input multiple-output (MIMO) technology to increase network reliability and enhanced data throughput has made it essential in modern wireless communication systems. In this study, a new X and Ku band MIMO antenna with improved isolation is designed and analyzed using a shared radiator. To improve system performance, the MIMO antenna system was built to provide greater isolation between antenna elements by inserting inverted H-shape parasitic components within the radiators, resulting in an out-of-phase current of a comparable magnitude to the coupling current. The antenna achieves an isolation level greater than 15 dB across the operational frequency of 8.5-18.5 GHz with overall dimensions of 25 × 22 × 0.5 mm3 on RT duroid 5880 substrate. Furthermore, the developed MIMO antenna is investigated for radiation characteristics, with a maximum gain of 5.8 dB and acceptable diversity features. A path loss study for the designed antenna is performed using the ABG and CI models under the urban macro and micro model scenarios. The proposed shared radiator quad port MIMO antenna is optimized to realize compactness, wider impedance bandwidth, and inter-port isolation. The antenna design outcomes from simulation and experimental data make it a good contender for use in contemporary communication systems.

A Wideband CPW Slot Antenna by Using Conductor-Backed Coplanar Feeding

In this paper, a new wideband coplanar waveguide (CPW) rhomboid slot antenna by using conductor-backed coplanar waveguide (CBCPW) feeding, which works at 4.6GHz with a relative impedance bandwidth of about 55.6%, and a gain of more than 5.5dBi from 4-6GHz, has been proposed, and the performance of a CPW circular slot antenna and a CPW rectangular slot antenna are also used for comparing with the proposed antenna. It is demonstrated that the CPW rhomboid slot antenna has wider impedance bandwidth, higher gain and better radiation pattern compared with the circular and rectangular slot antennas, meanwhile, low profile has also realized. The CPW rhomboid slot antenna with CBCPW feeding has been fabricated and measured, and the design has been verified.

Miniaturized circularly polarized wearable array antenna for medical device applications

Antenna miniaturization is essential for healthcare applications, and numerous studies have tackled the challenge of presenting miniaturized, reliable designs while maintaining performance. This paper presents a small circularly polarized (CP) sequential wearable array antenna with overall dimensions of only 110 mm × 95 mm × 1.8 mm. It comprises four novel designs of circular-shaped elements arranged sequentially in an array configuration measured only 24 mm×24 mm×1 mm. It is fed by a separate cascade feeding network incorporating a single rat-race and two branch-line couplers. The antenna is designed for medical device applications within the 2.4 GHz Industrial Scientific Medical (ISM) frequency band. The proposed design is fabricated and experimentally tested, demonstrating wide impedance bandwidths of 21.24% (2.2–2.72 GHz) and an Axial Ratio (AR) bandwidth (AR < 3 dB) covering the entire 2.4 GHz ISM frequency band. At 2.43 GHz, the antenna achieves a gain of -14.9 dBi. Both simulation and experimental results confirm excellent performance in impedance matching, gain pattern, and circular polarization, making it promising for wearable wireless communication in medical applications. The link margin was calculated, and the specific absorption rate of the antenna was analyzed, the result revealing that it aligns with the safety limits of IEEE C95.1-1999 standards.

Overview of Vivaldi Antenna Selection for Through-Wall Radar Applications

This paper analyzes broadband antennas, with a special focus on Vivaldi antennas, for their suitability for through-wall radar applications. It assesses various antenna designs, emphasizing high gain, wide impedance bandwidth, and effective wall penetration capabilities. Vivaldi antennas are superior due to their broad bandwidth, high gain, and directional radiation patterns. This study further explores structural optimizations, feeding techniques, and performance enhancement strategies to refine Vivaldi antenna designs for through-wall radar systems. Through a comparative analysis and technical evaluation, this paper highlights Vivaldi antennas’ potential for improving through-wall radar systems’ imaging and sensing capabilities. This presents a pathway for future ultra-wideband advancements.

Wideband and high gain elliptically-inspired 4 × 4 MIMO antenna for millimeter wave applications

An elliptically-inspired microstrip antenna is utilized in this paper to operate in the V-band (52.9–70 GHz) of the millimeter frequency range for 5G applications. 2-port and 4-port multi-input-multi-output (MIMO) configurations are designed, fabricated, and tested to validate the desired radiation and impedance characteristics. The measured results mimic the simulated ones in terms of scattering parameters, and MIMO parameters. Although the 4-port footprint is considered miniaturized (26 × 26 mm2), it provides a reduced coupling between ports (≤20 dB) with an improved gain ranging from 8 to 10.1 dBi. Furthermore, the achieved MIMO parameters (ECC, DG, CCL, and MEG) are distinct with values of 0.006, ≥9.96 dB, ≤0.4 bits/s/Hz, and −3 dB, respectively. The introduced 4-port MIMO antenna is compared with the state-of-the-art antennas and this assures that the suggested model has built-in size, wider impedance bandwidth, and higher isolation with an improved diversity characteristic confirming the possibility of the presented MIMO antenna to be a challenging candidate for 5G wireless communications.

Realizing Orthogonal Modes in Compact Cavity‐Backed Dual‐Polarized Antenna Through Simple Feeding Structures for Millimeter‐Wave AiP Applications

AbstractThis paper presents a dual‐polarized cavity‐backed antenna designed for mm‐wave applications, featuring simple feeding structures with a high‐isolation for 60 GHz compact AiP applications. The dual‐polarization design relies on two separate feed ports that excite two orthogonal modes within the same resonant cavity, achieving very high port isolation of up to 40 dB over the entire band. We conducted a detail analysis of the antenna, including its working principles and parametric studies. For verification, we fabricated an antenna test kit using standard printed process on substrates and measured the kit from the back‐side of a GSG probing platform. The proposed antenna demonstrates a wide impedance bandwidth, stable radiation patterns, very low cross‐polarization levels, and a high radiation efficiency. The co‐located cavity‐backed design ensures the compactness and facilitates easy integration with ICs in a very small AiP module. These features make the proposed antenna highly suitable for 60 GHz AiP applications, such as high‐data‐rate wireless communication and mmW polarimetric radar systems.

A High Gain Circularly Polarized Slot Antenna Array for 5G Millimeter-Wave Applications

An air-filled substrate-integrated waveguide (AF-SIW) circularly polarized (CP) 1 × 8 mm wave antenna array is presented for fifth-generation (5G) applications. The presented slot antenna array consists of three layers of PCB and one layer of aluminum, which serve as the AF-SIW feeding network and the metal cavity radiation element, respectively. The CP characteristic is achieved by the use of an S-shaped aluminum radiation cavity on the top of the AF-SIW feeding network. The air-filled substrate-integrated waveguide technique is unitized to achieve high radiation efficiency. A wide input impedance bandwidth of 18.4% is obtained for the proposed antenna scheme, ranging from 34.5 GHz to 41.5 GHz, with a peak gain of 18 dBic. As for CP characteristic, the proposed antenna possesses a wide 3 dB axial ratio (AR) bandwidth, which is 16.4% (36.5 GHz to 43 GHz). The antenna scheme is fabricated and measured to verify the potential application as well as the promising performance. The measured results of the 1 × 8 antenna array shows that the wide AR as well as the input impedance are simultaneously achieved, which coincide well with the simulated results. Also, the measured results indicate that the proposed antenna scheme might be a good candidate for future mobile applications.

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.

A low-profile ultra-wideband magneto-electric dipole antenna for ground penetrating radar

ABSTRACT Ultra-wideband antennas that operate at low frequencies usually have a large geometry, which makes them very limited in practical engineering application environment where space is often constrained. In this paper, a novel low-frequency low-profile ultra-wideband magneto-electric (ME) dipole antenna is designed for the application in ground penetrating radar (GPR) to detect deeply buried targets. The antenna is designed at the operation frequency of 230 MHz, so that the objects that are buried as deep as 1.5 m can be detected. Compared to the traditional low-frequency _antennas, it has a profile as low as 740 mm × 140 mm × 150 mm ( 0.49 λ × 0.09 λ × 0.10 λ ). Based on the simulation analysis and validation measurements, the proposed ME dipole antenna has a wide impedance bandwidth for S 11 < − 10 dB from 135 MHz to 382 MHz even when environmental influence is considered. The antenna is further validated with a GPR experiment, where a pipeline with a diameter of about 200 mm at 1200 mm beneath the road surface is successfully detected by an impulse GPR system where the proposed antennas are integrated.

Quad-band dual-port MIMO microstrip antenna with double integrated circularly polarized bands for 4G/5G wireless applications

Abstract A quad-band two-port MIMO antenna is presented with four operating bands at 2.4, 3.5, 5.8, and 8.2 GHz to serve WLAN, 4G LTE, 5G &amp; ITU applications, respectively. The wide impedance bandwidth of 13.33% (2.28–2.60 GHz), 21.62% (2.98–3.74 GHz), 8.9% (5.58–6.10 GHz) and 4.8% (8.00–8.44 GHz) is achieved at respective operating bands. The antenna also provides circular polarization at 3.5 GHz and 5.8 GHz. It is fabricated on FR4 substrate of 50 × 76 × 1.6 mm3 dimensions. The isolation between both ports is below 28 dB within all four operating bands. The radiation efficiency is about 90% in the first two bands whereas it is about 75% in the remaining two bands. The presented MIMO antenna shows better radiation characteristics along with satisfactory diversity performance. Experimental results of the fabricated prototype validate the simulated results.

A substrate-integrated waveguide-based wideband circularly polarized slot antenna using the parasitic square patch array

In this paper, a planar low-profile wideband circularly polarized substrate-integrated waveguide (SIW) based antenna is investigated. The antenna comprises two substrates stacked over each other. The top layer of the antenna is loaded with a 4 × 4 array of parasitic square patches stacked over a spiral slot loaded in the SIW cavity. The spiral slot is utilized for the generation of narrow band circular polarization and to enhance the CP bandwidth, the parasitic patch array is excited through the electromagnetic coupling mechanism without any air gap between them. The antenna is fabricated and tested to validate the simulated results. A wide relative impedance bandwidth of 33% (8.25–11.55 GHz) and the axial ratio bandwidth of 8.55–9.70 GHz (12.60%) is exhibited. The broadside radiation characteristics are achieved with peak gain of 8.05dBic at 9 GHz. The overall size of the antenna structure is 0.8λ0 × 0.8λ0. The proposed antenna is suitable for various satellite applications.

Wideband null frequency scanning monopole antenna under triple‐mode resonance

AbstractSemianalytical design approach to a triple‐mode resonant, wideband null frequency scanning sectorial monopole antenna is proposed. As is demonstrated, TE3/5,1, TE9/5,1, and TE3,1 mode within a 150°, circumferentially resonant sectorial monopole are simultaneously excited to realize null frequency scanning functionality. The prototype antenna exhibits a wide impedance bandwidth of 75.3%, ranging from 1.40 to 3.09 GHz. Within the frequency band of 1.55–2.70 GHz, the radiation null linearly scans from θ = +90° to +8° with a null frequency scanning sensitivity of 12.9 MHz/°. Moreover, the antenna possesses maximum gain of 2.5 dBi in the backfire, ‐x‐direction, which indicates that it should exhibit quasi‐unidirectional radiation pattern in the azimuth plane.

High‐gain dual‐wideband ±45° dual polarization (DWDP) antenna for indoor distributed antenna system (IDAS) applications

SummaryThis paper presents two different configurations of ±45° dual‐wideband dual‐polarized (DWDP) antennas. The antenna comprises eight end‐loaded broadband dipoles grouped into two sets based on the bands of operation. The high‐frequency dipoles are strategically placed within the low‐frequency ones to form the elementary unit. Further optimization has been performed on the elementary unit in terms of the radiator placement to suppress sidelobe levels for array formation. Both configurations are meticulously fabricated using an all‐metal structure, demonstrating durability and the simplicity of fabrication. The antenna designs achieve ±45° polarization, high gain, satisfactory cross‐polarization discrimination (XPD), and wide impedance bandwidth covering 0.67–1.04 GHz and 1.54–3 GHz bands. Despite the nested configuration, mutual coupling is well within acceptable limits. Formation of the array based on the optimum elementary unit has been investigated by simulation, revealing reasonable gain enhancement and low sidelobe levels across all bands. This comprehensive approach yields a robust, high‐performing antenna configuration suitable for indoor distributed antenna system (IDAS) applications.

An X/Ku‐band shared aperture antenna with open, short, and load‐ended series‐feed center‐fed chebyshev amplitude distribution array for AIR‐BORNE‐synthetic aperture radar

AbstractThis article presents a dual‐band shared aperture antenna array designed for ASAR applications. The antenna array comprises eight elements for Chebyshev array configurations in both X/Ku‐bands. The proposed array achieves a scanning angle of ±25° by employing an interelement spacing of 0.7 λ. The layout mitigates mutual coupling effects and provides good isolation performance between the X‐ and Ku‐band antenna arrays across all synthesis techniques. Adopting the open, short, and load antenna array achieves different side lobe level (SLL) performances, &gt;−25 dB. The isolation between bands and between the three conditions is quantified as follows: S16 = S61 = −68 dB, S15 = S51 = −55 dB, S12 = S21 = −46 dB, S43 = S34 = −49 dB, and S56 = S65 = −43 dB. The SLL values for each synthesis technique in the X/Ku‐band are as follows: Chebyshev simulated and measured results for open‐ended (X/Ku‐band: −26/−24 dB/−27/−26.8 dB). Furthermore, the antenna array achieves maximum realized gains in different positions (0°, 5°, 10°, 15°, 20°, 25°) in the X/Ku‐band. The gains for each synthesis technique are as follows: Chebyshev (The measured gain of this X/Ku‐band is high around 16.2/16.5 dBi (open‐ended), 13.1/14.2 dBi (short‐ended), and 15.3/15.2 dBi (load‐ended). The antenna array exhibits a comparatively wide impedance bandwidth Chebyshev (X/Ku‐band: 100/230 MHz).

Enhancing gain and isolation of a quad-element MIMO antenna array design for 5G sub-6 GHz applications assisted with characteristic mode analysis

This paper presents a novel quad-element array with multiple inputs and multiple outputs (MIMO) designed for 5th generation sub-6 GHz applications. The MIMO system achieves a wide impedance bandwidth, high gain, and high isolation among its components, representing significant advancements in sub-6 GHz antenna applications. The single element, an elliptical resonator with a circular slot, is fed by a 50 Ω microstrip feedline, achieves a broad characteristic bandwidth from 3.7 to 5.7 GHz with a resonant frequency of 4.33 GHz and a gain of 1.81 dBi. Characteristic Mode Analysis (CMA) was employed to elucidate the evolution phases of this design. The quad-element MIMO antenna array maintains a compact size and broadband characteristics by arranging mirrored elements on the same ground plane. Implemented on a cost-effective FR-4 substrate measuring 44 × 44 × 1.6 mm3, the recommended MIMO antenna array, enhanced with a partial ground plane and due to the introduction of a vertical strip, a high isolation of − 38.53 dB is achieved between MIMO components along with a realized gain of 3.01 dBi and a radiation efficiency of 71% in the 5G sub-6 GHz band. Noteworthy properties include high isolation, diversity gain (DG), and envelope correlation coefficient (ECC), verifying the appropriateness of the suggested MIMO scheme for 5G transmission and reception in sub-6 GHz applications.

Conformal wideband ingestible capsule MIMO antenna system for multi-channel communication in biotelemetry

This article presents the design of a compact conformal multiple-input-multiple-output (MIMO) capsule antenna aimed at enabling robust communication and high data rates over a broad frequency range spanning from 0.3 to 2.5 GHz. This range encompasses essential frequency bands such as medical implant communications services (MICS) (401–406 MHz), wireless medical telemetry services (WMTS) (1.4 GHz), and industrial, scientific, and medical (ISM) (0.433 GHz, 0.915 GHz, and 2.45 GHz) for wireless capsule biotelemetry. The size of the capsule is reduced to 17 mm × 7 mm (typically 26 mm × 11 mm) to ensure the safe passage of the capsule without being trapped inside the intestine. The proposed antenna (integrated with dummy electronics to build a fully encased capsule endoscope design) is placed inside homogeneous and heterogeneous phantoms in the simulation. The antenna prototype is fabricated, and performance metrics are measured by implanting it inside pork meat and phantom solution. The proposed MIMO antenna offers a wide impedance bandwidth of ∼2200 MHz, and the measured isolation between the antenna elements is > 20 dB. The proposed antenna is also tested for robustness (interaction between the electronic components and the endoscope’s antenna) and human safety using system considerations and realistic voxel models.

Design of circular slots loaded MIMO antenna with DGS at 28 GHz for 5G wireless services

In this paper, a MIMO microstrip patch antenna with four radiating elements is designed and analyzed at 28 GHz. This paper addresses the problem of mutual coupling without adding a decoupling network. The decoupling method increases the complexity and volume of MIMO antennas. The CST Microwave simulator is used to simulate the MIMO antenna. The simulation and measurement results are compared to analyze the antenna's performance. The parameters of the MIMO patch antenna, including return loss, VSWR, gain, beam width, and radiation pattern, are evaluated at a center frequency of 28 GHz. The overall dimensions of the MIMO antenna are 60 × 42 × 1.6 mm3.An H-shaped slot is inserted in the middle of the ground plane to minimize mutual coupling among the radiating elements. The isolation amplitude between radiating elements is observed greater than 35 dB at 28 GHz frequency. A wide impedance bandwidth of 4 GHz (26.5 to 30.5) is achieved, by etching four small arcs into the patch’s corners. In this work, two circular slots are inserted on the radiating element to widen the bandwidth further by adjusting the surface current on each radiating patch. At the center frequency of 28 GHz, the Envelope Correlation Coefficient (ECC) is observed to be 0.0001, with a diversity gain of 10 dB. The antenna has a maximum radiation efficiency of 75% and a peak gain of 7.62 dB. This antenna can be used for 5G wireless services.

Impedance Bandwidth Enhancement Using Capacitor-Controlled Series Resonance in an Antenna’s Feeding Structure

This paper introduces a feeding structure that employs a series capacitor and a parallel capacitor to control input impedance. Accordingly, a wide impedance bandwidth was achieved in a simulation. A comparative analysis of the characteristics of the reference antenna and the proposed antenna was conducted to demonstrate the proposed antenna’s improved bandwidth and enhanced efficiency. According to the simulation and measurement data, the bandwidth of the proposed antenna was approximately 400 MHz (range, 680–1,080 MHz) under a 3:1 voltage standing wave ratio. Moreover, the efficiency improved from 43% to 59% (range, 690–960 MHz), and the radiation pattern showed satisfactory performance. The proposed technology thus offers promising development prospects for the antenna designs of low-frequency systems for mobile communication.

A broadband transparent antenna applied in indoor mobile communication system

AbstractThis paper proposes a broadband optical transparent antenna using a transparent conductor film on a transparent polyethylene terephthalate (PET) substrate. The planar wide‐slot antenna coupling fed by microstrip has a wide impedance bandwidth, so it is selected to design the transparent antenna. The upper surface of the PET substrate is a microstrip line with a fork‐shaped tuning branch, and the lower surface is a wide slot. They were made of transparent conductor film. Finally, a new capacitive coupling method is used to feed the transparent antenna. The transparent conductor film used in the antenna is metal mesh, which was developed by 3M company. The metal mesh with an open area greater than 80% to achieve high transmittance. The measured results show that the impedance bandwidth is 177% (0.30–5.0 GHz), and the gain of the antenna varies from 5.06 to 7.8 dBi over the entire frequency band. Therefore, it can be well applied to the current indoor mobile communication system.

Wideband circularly polarized antenna loaded with π‐shaped dipole for millimeter‐wave applications

AbstractThis paper presents a novel wideband circularly polarized antenna that is fed by substrate‐integrated waveguide. Based on the design of placing a pair of chamfered semicircular patches above a slot, a ‐shaped radiator is introduced between the semicircular patches. Multiple resonance points are generated by the combination of the entire radiating structure and a dumbbell‐shaped slot, resulting in improved impedance bandwidth and axial ratio (AR) bandwidth. The proposed element exhibits a wide impedance bandwidth of 50.5% (24.5–41.1 GHz) and an AR bandwidth of 44.2% (25.1–39.3 GHz) with a 44.2% overlapped bandwidth. Then, a 4 × 4 antenna array adopting the sequential rotation technique is constructed. The measured results demonstrate that a 40.6% overlapped bandwidth and a peak gain of 19.1 dBic are achieved. The proposed antenna array shows excellent performance, making it a good candidate for applications in millimeter‐wave wireless communication systems.