Tapered Feed Line Research Articles

INVESTIGATION OF THE EFFECTS OF DIFFERENT FEED LINE STRUCTURES ON UWB ANTENNA PERFORMANCE BY CHARACTERISTIC MODE ANALYSIS

This study investigates the effect of various feed topologies on the parameters of a novel ultra-wideband (UWB) antenna using characteristic mode analysis. The proposed design is guided by characteristic mode analysis, commencing with a basic square structure. Initially, a closed-form estimate of the resonance frequencies of the primary modes is provided for the square-shaped structure. Subsequently, the characteristic modes that resonate in the frequency spectrum are modified by introducing symmetrical square slots. To excite these modes and achieve a wideband antenna that encompasses the relevant spectrum, the geometry of the feeding line is altered and its effects are examined. The study incorporates two fundamental feed line geometries: tapered and traditional feed impedance lines. The proposed UWB antennas are fabricated and measured to validate their performance. According to the measurement results a wide impedance bandwidth of 147.82% at -10 dB reference ((0.9–6 GHz)) and stationary radiation patterns across the operating frequency band are obtained for the tapered feed line. The results demonstrate a significant advantage of the tapered feed line over the traditional impedance line. The results for the fabricated prototypes exhibit high similarity to the simulated results. The findings confirm the applicability of the mode analysis method.

Design and Fabrication of Compact MIMO Array Antenna with Tapered Feed Line for 5G Applications

In this paper, we design, fabricate, measure, and report two proposed multiple input multiple output antenna elements (MIMOs) with good performance in the 5G band. The MIMO antennas are mounted on Roger / Druoid 5880 substrates (dielectric constant: 2.2) with an overall structure volume 20×24.14×0.79mm3. First, a comprehensive parametric study is performed based on CST Electromagnetic (EM) Simulator to investigate and enhance the antenna performance in relation to 5G application requirements. Second, as part of the antenna design process, we compute the envelope correlation coefficient (ECC > 0.01dB) and diversity gain (DG> 9.9dB) and achieve good results. Third, we provide fabrication and measurement verification with good agreement. Fourth, we use a tapered feed structure with inset feed to minimize mutual coupling and achieve matching along 2 transmission lines with various impedances with high compactness in the antenna structure. Fifthly, we report that the proposed antenna structure has a gain is 8 dBi (dB) at the relevant operating frequency band (24.25

4X4 MIMO slot antenna spanner shaped low mutual coupling for Wi-Fi 6 and 5G communications

Multiple-input multiple-output (MIMO) antennas are essential for modern wireless communication systems that require high data rates, reliability, and quality. However, designing MIMO antennas poses several challenges, such as achieving high isolation, low mutual coupling, low envelope correlation coefficient (ECC), high gain, and high efficiency in a compact size. In this paper, we propose a novel MIMO antenna design that can overcome these challenges and support various wireless applications, such as WiFi-6, 5G (n77/n78/n79), and satellite communications. The proposed design consists of four spanner-shaped radiating elements that are etched on an FR-4 substrate with a tapered feeding line. The spanner-shaped antenna is derived from an octagonal ellipse that is cut by another octagonal ellipse to form the shape of the antenna. The proposed design achieves dual operating bands of 3.3–3.8 GHz and 4.5–8.4 GHz with low mutual coupling (<−10 dB), low ECC (less than0.05), high gain (up to 4 dBi), and high efficiency (>80%). The proposed design is compared with other MIMO antenna designs in the literature and shows its advantages in terms of size, performance, and applicability.

Design and analysis of a super compact UWB antenna for accurate detection of breast tumors using monostatic radar‐based microwave imaging technique

AbstractThis article proposes a low‐profile ultra‐wideband (UWB) antenna for breast tumor detection using the monostatic radar‐based microwave imaging (RBMI) technique. The proposed UWB antenna consists of a circular patch and ground plane along with a modified tapered feed line having a total size of 13 × 9 × 1.6 mm3. The designed antenna operates from 4 to 11 GHz based on a −10 dB reflection coefficient with a peak gain of 9.5 dBi at 4.8 GHz. Experimental validation is carried out after fabricating the prototype of the UWB antenna and the breast mimic. The measured backscattered signals are captured using the vector network analyzer (E‐5063A) by keeping the antenna at 10 mm from the breast phantom. After that, post‐processing of the measured data is done to detect the exact depth and location of the malignant tissue. The proposed antenna uses UWB band frequency of operation because it has some unique features, that is, it provides immunity to multipath fading, has a simple design, has a low cost of fabrication, and has biological friendliness. Moreover, due to the proposed antenna's resonance at a lower resonant frequency better depth of penetration is achieved in human body phantoms and the proposed antenna provides specific absorption rates (SAR) of 0.877 W/kg over 1 g of tissue at 4.8 GHz, which is an acceptable limit for SAR as per FCC guidelines. Therefore, the proposed antenna and monostatic RBMI technique are good candidates for breast tumor detection.

Low-Profile Antenna System for Cognitive Radio in IoST CubeSat Applications

Since the CubeSats have become inherently used for the Internet of space things (IoST) applications, the limited spectral band at the ultra-high frequency (UHF) and very high frequency should be efficiently utilized to be sufficient for different applications of CubeSats. Therefore, cognitive radio (CR) has been used as an enabling technology for efficient, dynamic, and flexible spectrum utilization. So, this paper proposes a low-profile antenna for cognitive radio in IoST CubeSat applications at the UHF band. The proposed antenna comprises a circularly polarized wideband (WB) semi-hexagonal slot and two narrowband (NB) frequency reconfigurable loop slots integrated into a single-layer substrate. The semi-hexagonal-shaped slot antenna is excited by two orthogonal +/−45° tapered feed lines and loaded by a capacitor in order to achieve left/right-handed circular polarization in wide bandwidth from 0.57 GHz to 0.95 GHz. In addition, two NB frequency reconfigurable slot loop-based antennas are tuned over a wide frequency band from 0.6 GHz to 1.05 GH. The antenna tuning is achieved based on a varactor diode integrated into the slot loop antenna. The two NB antennas are designed as meander loops to miniaturize the physical length and point in different directions to achieve pattern diversity. The antenna design is fabricated on FR-4 substrate, and measured results have verified the simulated results.

CPW fed shovel shaped super wideband MIMO antenna for 5G applications

A shovel shaped antenna operating from 4.1 to >60 GHz to cover C/X/Ku/K/Ka/Q/U bands along with 5G bands n257/n258/n259/n260/n261/n79/60 GHz is presented in this paper. It consists of a modified square patch, tapered feed line and modified defected coplanar waveguide ground planes. A half-wavelength split ring resonator (SRR) is used to achieve X-band satellite downlink (6.8–7.8) GHz band notch. It has dimensions of 20 × 14 mm2, quasi-stable radiation patterns, a maximum peak realized gain of 9 dBi, fidelity factor > 50%, |S21| > 32 dB and linear S21 phase response. It’s two element spatial diversity configuration has footprint of 20 × 36 mm2, operating bandwidth of 4.3 to >60 GHz with notch band characteristics and isolation >15 dB due to hybrid decoupling structure. The pattern diversity configuration has footprint of 20 × 41.5 mm2, impedance bandwidth of 4.3 to >60 GHz for Port 1 & 3.9 to >60 for Port 2 and isolation >21 dB due to hybrid decoupling structure. Both MIMO antennas have ECC≤0.01, DG≅10, TARC < -10 dB, ηmux > -3.5 dB and CCL≤0.3 b/sec/Hz and channel capacity of ∼11.34b/sec/Hz. The proposed antenna geometries are dominating previously reported structures in terms of superwide bandwidth, compact dimensions, high BDR ∼3335, high peak gain and good diversity performance with less intra element spacing.

A broad axial ratio bandwidth and wide angle coverage circularly polarized monopole antenna for wireless communication

AbstractA uniquely shaped layout of a wideband circularly polarized (CP) printed monopole antenna is planned in this article. The proposed antenna comprises a 7‐shaped slotted radiating patch, tapered feed line, and modified partial ground plane. Multiple parasitic strips are employed at optimum positions on the ground and radiating planes to improve the axial ratio bandwidth (ARBW). The electrical dimension of the designed antenna is . The confirmed −10 dB impedance bandwidth (IBW) and 3 dB ARBW are 11.86 GHz (3.14–15 GHz), 130% and 6.32 GHz (4.04–10.36 GHz), 87.78% along with coverage angle. The proposed antenna is suitable for different applications in communication systems such as WLAN, WiMAX, FM CW altimeter, and satellite for C‐ and X‐ band.

A novel circular fractal ring UWB monopole antenna with dual band‐notched characteristics

AbstractThis paper presents a novel circular fractal ring monopole antenna for ultra‐wideband (UWB) hardware with dual band‐notched properties. The proposed antenna consists of four crescent‐shaped nested rings, a tapered feeding line at the front of the dielectric material, and a semicircular ground plane on the backside. In this design, the nested rings are used both as a radiation element and a band rejection element. The proposed antenna has a bandwidth of 9.03 GHz, which works efficiently in the range of 2.63 GHz–11.66 GHz with the dual notched bands of Worldwide Interoperability for Microwave Access (WiMAX) at 3.15 GHz–3.66 GHz and wireless local area network (WLAN) at 4.9 GHz–5.9 GHz, respectively. The antenna has a compact size of 20 mm × 30 mm × 1 mm (0.177 × 0.265 × 0.0084 λ0) and is implemented using a flame‐retardant type 4 (FR4) material. It has a maximum gain of approximately 4 dB in its operating range, and experimental results support the simulation predictions with high accuracy. The findings of this study imply that the designed antenna can be utilized in UWB applications.

Quad element MIMO antenna for LTE/5G (sub-6 GHz) applications

A quad-element multiple-input-multiple-output (MIMO) antenna with fractional bandwidth (FBW) of 52.42% (3.35–5.73 GHz) is proposed for LTE, WLAN (4.9/5 GHz), and 5G (sub-6 GHz) applications. The bandwidth is improved by introducing a tapered feed line and rectangular stubs in the partial ground plane. The maximum isolation of the proposed MIMO antenna is 27 dB. The diversity performance characteristics of the proposed antenna are studied in terms of the envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), isolation between the ports, and channel capacity loss (CCL) and the values obtained are 0.003, 9.98 dB, ±3 dB, −4 dB, −10 dB, and 0.10 bits/s/Hz respectively. A model of the proposed antenna is fabricated on the FR-4 substrate having a dielectric constant of 4.4 and a loss tangent of 0.02 with an electrical dimension of 0.45λ0 × 0.45λ0. The measured results demonstrate a decent likeness to simulated ones in the entire operating frequency range.

Design and Study of a Miniaturized Millimeter Wave Array Antenna for Wireless Body Area Network

A miniaturized millimeter wave (mmWave) antenna for wireless body area networks is proposed in this paper. The antenna is found to be operational in the V-band, around the 60 GHz frequency range, with high efficiency of up to 99.98% in free space simulations. A multilayer, thin substrate was implemented in the design to enhance radiation efficiency and gain. The antenna seems to be most suitable for small electronic devices and wireless body area network (WBAN) applications because of its low profile and lighter weight concept. To enhance its performance, several arrays of different orders were created. The Parallel-Fed and Tapered Feed Line methods were followed to design the planar arrays with 1 × 2, 1 × 4, and 2 × 2 elements in the primary design. Free space results were compared, and a 2 × 2 element array was found to be the most balanced according to the simulations. To justify the eligibility of these designs for WBAN applications, a virtual human body model was created within the 3D computer-simulated environment and the simulations were repeated, where four equal-spaced distances were taken into account to identify the antenna and its array behavior more accurately. Simulations returned optimistic results for the 2 × 2 element planar array arrangement in almost all parameters, even when placed close to the human body at any distance greater than 2 mm.

Increasing radiation power in half width microstrip leaky wave antenna by using slots technique

&lt;p class="Default"&gt;The radiation power in the endfire is decreased while the main beam of half substrate integrated waveguide scan from broadside to endfire in a forward. The design of half-width microstrip leaky-wave antenna (HW-MLWA) has been presented in this work to increase the power radiation near endfire by using the slots technique in the radiation element. This slot leads to a decrease the cross-polarization. The proposed design comprises one element of HW-MLWA with repeated meandered square slots in the radiation element. One aspect of this antenna is generated by using a half substrate integrated waveguide with a full tapered feed line. The proposed antenna was terminated by load of 50 Ω, and feed on the other end of the antenna. Finally, the suggested design is simulated and acceptable results were found. The released gain is increased from 10.6 dBi to 12 dBi at 4.3 GHz. This design is suitable for unmanned aerial vehicle UAVs at C band application.&lt;/p&gt;

Compact CPW‐fed ultra‐wideband ‐MIMO antenna with quad‐band notched characteristics

A compact CPW-fed ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna with quad-band-notched characteristic is proposed in this work. The antenna elements are placed orthogonally, the introduction of defected ground structure (DGS) and double Y-shaped stub makes the isolation between different antenna ports better than 20 dB, and the cutting of the excess dielectric substrate part reduces the antenna area by about 30.75%. Complementary split-ring resonators and slots on the ground and the radiation patch have been introduced to achieve the four-notch characteristics at 7 GHz lower digital microwave relay communicator band, 5.8 GHz upper WLAN, 5.25 GHz lower WLAN, and 3.5 GHz WiMAX. The wide bandwidth of the antenna is obtained by applying tapered feed line and CPW feed, which covers 2.88–12 GHz with the four-notched bands of 3.34–3.93 GHz, 5.15–5.61 GHz, 5.72–6.0 GHz, and 6.75–7.6 GHz. Moreover, ECC (<0.02), DG (>9.99), the peak gain of 4.01 dB, good radiation pattern and TARC prove the presented antenna is suitable for UWB-MIMO systems.

Pentagon inscribed circular superwideband fractal MIMO antenna

SummaryA compact circular fractal antenna element loaded with a central pentagonal slot is presented in this paper. This structure consists of a fourth iterative radiator fed by a partially tapered feed line and CPW defected ground plane. A superwide impedance bandwidth of 3.45–52.17 GHz (~175% fractional bandwidth) is achieved. Two multiple input multiple output (MIMO) configurations are also designed and analyzed by using this antenna element. For spatial and pattern diversity configurations, the impedance bandwidth of 3.45–52.2 and 3.1–52.2 GHz are achieved, respectively. The optimized footprints of antenna element, spatial diversity configuration, and pattern diversity configurations are 28 × 24, 28 × 53, and 45 × 48 mm2, respectively. The isolation for both MIMO configurations is more than 20 dB in maximum portion of the operating bandwidth. Desirable radiation and diversity performance characteristics are achieved for antenna element and MIMO configurations. The wide bandwidth, compact dimensions along with good radiation, and diversity performance characteristics make the proposed antenna configurations suitable for integration in superwideband wireless communication systems. A good agreement between the experimental and simulation results is observed.

A Non-Invasive Flexible Glucose Monitoring Sensor Using a Broadband Reject Filter

In this paper, a novel, highly accurate, non-invasive glucose-monitoring sensor that is based on a flexible broadband reject filter is presented. The filter topology comprises a tapered feed line at a top layer that excites four open loop resonators on the bottom layer. The broadband reject response is achieved by relying on a modified log-periodic distribution of the open loop resonators. The embedded resonators are reduced in size and are designed to exhibit an enhanced sensitivity to track the variations of the glucose level across the 1.25-2.65 GHz frequency span. The proposed flexible filter is tested within in-vitro, ex-vivo and in-vivo setups. A high correlation between the scattering parameters of the proposed sensor and the variations in glucose levels is attained. Regression models are developed using experimental data obtained from healthy patients that are subjected to glucose tolerance tests. Results demonstrate less than 4% mean absolute relative difference between the reference and estimated glucose levels, and the predicted glucose levels lie 100% within the clinically acceptable zones as shown by the Clarke Error Grid analysis.

Compact CPW-fed super wideband planar elliptical antenna

AbstractA compact co-planar waveguide (CPW) fed planar elliptical antenna has been designed and presented for super wideband (SWB) characteristics. The designed antenna has an overall size of 30 × 30 × 1.57 mm3, and it consists of an elliptical patch radiator fed using a modified 50 Ω CPW-fed tapered microstrip feed line. By using a semi-ring shaped structure with a tapered feed line, an impedance bandwidth of 180.66% has been observed from 1.27 to 25 GHz with a ratio bandwidth of 19.68:1. To validate simulation results, the designed antenna has been fabricated and measured, and a reasonable agreement has been observed between simulated and measured results. It has also been observed that the designed antenna offers good radiation properties over the entire operating bandwidth. The simulated average gain and radiation efficiency of the proposed SWB antenna is noted to be 4.3 dBi and 95.77%, respectively; while the measured average gain and radiation efficiency is 3.8 dBi and 94.69%, respectively.

Design of a tapered CPW-fed wideband antenna and its application to multi-channel transmission using a hybrid wireless communication system

A tapered Coplanar Waveguide (CPW)-fed wideband antenna with a nearly omnidirectional radiation pattern in the H-plane and a stable dipole-like radiation pattern for the E-plane is presented. The proposed antenna operates in two wide bands centered at 3.3 and 5 GHz. Furthermore, the antenna structure consists of a tapered feed line, which provides an impedance transformation from the quarter-wave monopole impedance to the 50 Ω input characteristic impedance. Also, two trapezoidal ground planes are added between the monopole and the CPW to achieve impedance matching. Variations in the antenna dimensions are included to monitor the bandwidth and to evaluate the efficiency of impedance matching. Moreover, in order to evaluate the performance of the proposed antenna, a hybrid wireless communication system is used to simultaneously transmit two analog TV signals. These TV signals modulate two microwave subcarriers located at 3.3 and 5 GHz. The resulting multiplexed signal is propagated between two antennas that are separated by a distance of 1 m. The modulated subcarriers are transmitted over an optical link of 30 km by using an optical communication system based on external modulation. The signal at the end of the optical link is successfully recovered by using a conventional demodulation scheme.

A polarization reconfigurable discontinuous ring dipole antenna

AbstractA circularly polarized antenna is realized using a discontinuous ring dipole. With the introduction of p‐i‐n diodes, it has been possible to achieve polarization reconfigurability in the antenna. The antenna is fed by a tapered feed line, which also acts as a balun and biasing structure. The sense of rotation of the electric field vector (left‐hand or right‐hand) can be controlled by switching the states of the diodes. An equivalent circuit of the antenna is proposed, which has been used to compute the input reflection coefficient of the antenna. The performance of the antenna is verified by comparing the simulated results with the measured results. It has been observed that the antenna has 8.56% overlapping CP bandwidth (a common bandwidth for |S11| ≤ −10 dB and axial ratio, AR ≤3 dB) from 5.03to 5.48 GHz. A measured gain of 3.61 dBic is obtained for all polarization states. The proposed antenna can be used for the 5.2 GHz Wi‐Fi application.

Design of printed monopole antenna with band notch characteristics for ultra‐wideband applications

A novel design of printed monopole antenna for the ultra-wideband (UWB) applications with band notch characteristics at wireless local area network (WLAN) and X-band satellite communication system has been proposed in this manuscript. Two different types of feed lines, that is, simple and tapered are used to excite the proposed antenna. Initially, designed antenna is excited by using simple 50 Ω transmission line after that tapered transmission line is introduced to enhance the impedance matching throughout the UWB frequency range (3.1-10.6 GHz). A comparison of designed antenna with simple and tapered feed line on the basis of impedance matching has also been made in this article, and found that later case reports better impedance matching in terms of Voltage Standing Wave Ratio (VSWR) bandwidth (2.45-12.0 GHz). Further, the notch bands are embodied into the designed antenna by using two split ring slots and one horizontal slot. The antenna with outer ring slot rejects the WLAN frequency band and antenna with inner ring junks the X-band satellite communication signal. The notch frequency has been adjusted by optimizing the dimensions of split ring slots as well as horizontal slot, which are incised on the structure of proposed antenna. By adjusting all the parameters of the etched slots of proposed antenna, dual band notched characteristics centered at frequencies 5.4 and 7.4 GHz has been achieved. Designed antenna is also compact (30 × 30 mm2) and capable to suppress the interference of WLAN and X-band satellite communication signal from the entire range of UWB passband. The proposed antenna is designed on low cost FR4 glass epoxy substrate with 1.6 mm thickness and dielectric constant 4.4. Antenna is designed and simulated by using HFSS V13 simulator and further, it is fabricated and tested for the validation of results. Simulated and measured results are also juxtaposed and found in good agreement with each other.

Compact design of trapezoid shape monopole antenna for SWB application

AbstractIn this article, a compact design of the monopole antenna is proposed for the super‐wideband application (SWB). The extremely wide frequency bandwidth is achieved by deploying a topology based on trapezoid shape radiator, triangular tapered feed line, and semicircular ground. The antenna shows resonance from 1.42 GHz to more than 90 GHz with a bandwidth ratio of 63.30:1, VSWR ≤2 and with S11 ≤ −10 dB. The electrical dimension of the monopole antenna is 0.16λc × 0.27λc where the wavelength λc is with respect to the lowest cut‐off frequency. The designed monopole antenna is fabricated on the F4B substrate. The prototype is experimentally validated for ultrawideband and SWB application. The experimental and simulated results are in good agreement and the designed antenna shows better performance of a wideband operation, compact electrical dimension, and high bandwidth dimension ratio over existing reported structures. The proposed antenna can be used for multiple bands such are ISM, Wi‐Fi, WLAN, WiMAX, C, S, X, K, and Ku bands.

Miniaturised UWB antenna with dual‐band rejection of WLAN/WiMAX using slitted EBG structure

This study presents a new slitted electromagnetic bandgap (EBG) structure to filter undesired wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) bands in the ultra-wideband (UWB) spectrum. A simple UWB antenna which consists of a microstrip tapered feed line, a circular patch and a defected ground structure is used as a reference antenna. The antenna is then integrated with a slitted EBG structure near the feed line to notch two interfering bands. The created notched bands by the EBG structure can be independently controlled. Owing to structural symmetry of the proposed antenna, the size can be reduced by approximately half to form a miniaturised antenna. The miniaturised antenna has the same full-size antenna characteristics with little change in the notched bands specifications. Frequency domain measurement results show that the full-size and miniaturised antennas have a flat transfer function, and a group delay variation of about 0.5 ns in the entire UWB band except for the notched bands.