Transmission Line Feed Research Articles

A Compact and Flexible Monopole Antenna with Controllable Bandwidth

In this paper, a compact antenna with flexible and controllable bandwidth characteristics is proposed. To ensure wide coverage along with an omnidirectional radiation pattern, a monopole structure was utilized as the primary radiating element of the proposed antenna. The monopole was fed using a coplanar waveguide technique to achieve a single-layer design. To alter the operating bandwidth, defined by a reflection coefficient of less than -10 dB, a single stub was directly connected to the feeding transmission line. By controlling the stub's length, matching performance in the high-frequency range was found to undergo significant degradation, indicating that the operating bandwidth could be controlled. Furthermore, for validation, two antenna prototypes were fabricated and measured under different circumstances. In the unbending mode, the design without the stub achieved a wideband of 51.6%, while the other design with the stub exhibited a narrower band of about 19.6%. Additionally, the antennas worked efficiently when operating in bending mode. It is also worth noting that the antenna gain and radiation pattern remained stable across the entire operating bandwidth.

Feeding‐line‐based decoupling patch antennas

AbstractMutual coupling among multiple antennas has been a problem needed to be tackled in multiple‐input‐multiple‐output (MIMO) systems. A decoupling method based on short decoupling feeding lines (DFLs) for MIMO patch antennas is proposed. The decoupling method utilises the feeding transmission line to create a new coupling path between the closely placed patch antennas. By adjusting the intensity and phase of the introduced new coupling, the original coupling can be cancelled out. The proposed method can realise both E‐ and H‐plane decoupling. A 1 × 2 H‐plane MIMO patch antenna array is first presented to explain the decoupling mechanism. Then, two practical examples of 2 × 2 and 4 × 4 MIMO patch antenna arrays are designed, fabricated and measured. The results indicate that the port isolation can be apparently improved from 15 to 38 dB for H‐plane coupling and from 19 to 35 dB for E‐plane coupling at the centre frequency of 3.5 GHz. Moreover, the proposed method is promising to be applied in arrays with other antenna type by adjusting the position and size of short DFLs.

Determination of Highly Transient Electric Field in Water Using the Kerr Effect with Picosecond Resolution

This study utilizes the Kerr effect in the analysis of a pulsed electric field (intensity ~108 V/m, limited by the liquid dielectric strength) in deionized water at the sub-nanosecond time scale. The results provide information about voltage waveforms at the field-producing anode (160 kV peak, du/dt > 70 kV/ns). The analysis is based on detecting the phase shifts between measured and reference pulsed laser beams (pulse width, 35 ps; wavelength, 532 nm) using a Mach–Zehnder interferometer. The signal-to-noise ratio of the detected phase shift is maximized by an appropriate geometry of the field-producing anode, which creates a correctly oriented strong electric field along the interaction path and simultaneously does not electrically load the feeding transmission line. The described method has a spatial resolution of ~1 μm, and its time resolution is determined by the laser pulse duration.

An improved Mini Antenna Designed at 60GHZ for a New Generation Mobile Phone

Five-generation (5G) communication systems are being required to meet the needs of small, high-speed, and big bandwidth systems [2]. This paper simulates and designs a 60GHZ rectangular micro strip patch antenna. The proposed antenna resonates at 60GHZ with a return loss of -32.126 dB, efficiency of 87.7119%, and gain of 6.96485 dBi. The patch is 2.726 x 2.364 x 0.125 mm. The radiating patch and the 50Ω micro strip feed line are matched using an iset feed transmission line approach. A Roger RT Duroid 5880 substrate, with a height of 0.125mm and a dielectric constant of 2.20 and a loss tangent of 0.0009, was selected in the design. The Advanced Design System (ADS) was used to compute the antenna's parameters and evaluate the results of simulations.

A single feed circularly polarized dual band microstrip monopole antenna for wireless applications

AbstractThe paper proposes a circularly polarized dual band single feed microstrip monopole antenna. The proposed antenna consists of a radiating patch, a shrink ground plane, and a 50 Ω microstrip transmission line feed. The radiating patch is a combination of three modified metallic strips, a modified rectangular strip and a semicircular strip. The ground plane consists of two modified open ended slots. The substrate area of the antenna is only 40 mm × 42 mm × 1.6 mm. The antenna has been designed by HFSS simulation software and after getting simulated results the antenna has been fabricated to verify its results. The antenna provides measured bandwidths (−10 dB impedance bandwidth) of 600 MHz (2.2–2.8 GHz) in the lower band and 2.1 GHz (7.5–9.6 GHz) in the higher band. The measured results show its 3 dB axial ratio bandwidth of 120 MHz (2.2–2.32 GHz) for lower band and 1.4 GHz (7.2–8.6) GHz for the upper band. The high measured peak gain of 8 dBi has been obtained from the proposed antenna. The lower band is useful for WiMAX application and upper band is useful for C band application. The desired radiation patterns (RHCP and LHCP) have been obtained from the proposed antenna.

Digital Fault Locator for Double End Fed Transmission Lines

The paper presents a digital fault locator by dynamic system parameter estimation for a double end fed transmission line. The method uses about 1/6 cycle of recorded fault data and doesn‟t require filtering of dc offset and high-frequency components. The system differential equations are based on a lumped parameter line model, Thevenin equivalents at both ends of the line and an unknown fault resistance. The accuracy is demonstrated by a representative set of tests results obtained with computer simulation

Engineering planar antenna using geometry arrangements for wireless communications and satellite applications

A triple-band microstrip patch antenna designed for the IEEE 802.16e WiMAX, IEEE 802.11a WLAN, C-band downlink communications, and Ku-band radar recent applications is suggested in this article. The planned antenna operates at 2.45, 6, and 14 GHz resonant frequencies. The antenna fulfilled triple-band physical characteristics covering industrial, scientific, and medical (ISM) bands between (2.1–2.8) GHz; (5.6–6.5) GHz for wireless local area network (WLAN) or ultra-wideband (UWB) services; and 12.7–16 GHz for future two-way 5G:6G either broadcasting or mobile satellite communications. To achieve better return loss performance, parametric studies are carried out using Microwave Studio (CST MWS). The proposed antenna is designed on the FR4 as a hosting medium of total size 46 × 38 × 1.6 mm3, combined with a planar transmission line (T.L.) feed and defected ground structure (DGS). The simulated antenna’s input reflection coefficient (S11) results and the far-field measurements show good agreement. The fabricated prototype achieves peak gain values of 2.8, 3.8, and 4.7 dBi, respectively, and bidirectional radiation characteristics. A comparative study with other recent publications is implemented to validate the consistency of the design.

1-D and 2-D Beam Steering Arrays Antennas Fed by a Compact Beamforming Network for Millimeter-Wave Communication

In this article, a new Beamforming Network (BFN) realized in Broadside Coupled Stripline (BCS) is proposed to feed 1 × 4 and 2 × 2 arrays antenna at 28 GHZ-Band. The new BFN is composed only of couplers and phase shifters. It doesn't require any crossover compared to the conventional Butler Matrix (BM) which requires two crossovers. The tight coupling and low loss characteristics of the BCS allow a design of a compact and wideband BFN. The new BFN produces the phase differences of (±90°) and (±45°, ±135°) respectively in x- and y-directions. Its integration with a 1 × 4 linear array antenna reduces the array area by 70% with an improvement of the gain performance compared with the conventional array. The integration with a 2 × 2 array allows the realization of a full 2-D beam scanning. The proposed concept has been verified experimentally by measuring the fabricated prototypes of the BFN, the 1-D and 2-D patch arrays antennas. The measured 11.5 dBi and 11.3 dBi maximum gains are realized in θ0 =14° and (θ0, ϕ0)=(45°,345°) directions respectively for the 1-D and 2-D patch arrays. The physical area of the fabricated BFN is only (0.37λ0 × 0.3λ0 × 0.08λ0), while the 1-D array and 2-D array antennas areas without feeding transmission lines are respectively (0.5λ0 × 2.15λ0 × 0.08λ0) and (0.9λ0 × 0.8λ0 × 0.08λ0).

A Ka-Band Broadband Polyjet 3-D Printed Quasi-Planar End-Fire Antenna With Partially Hollowed Substrate and Gain Compensation

This letter presents a new class of millimeter-wave broadband quasi-planar end-fire antenna featuring flexible design and enhanced structural compatibility with additive manufacturing technology. The broadband end-fire radiation performance is enabled by a coupling-probe-fed rectangular patch that is vertically attached to the sidewall of dielectric substrate of the antenna. The patch and ground of the antenna are perpendicular to the plane of the feeding transmission line and the metal parts of the antenna are embedded into the dielectric substrate. The architecture allows excitation of vertically polarized patterns of the patch. More significantly, the dielectric substrate is hollowed selectively to improve the realized gain in the main-lobe orientation, thus enhancing stability of the radiation patterns in a wide operational bandwidth. A <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ka</i> -band prototype of the proposed antenna is shaped into a 3-D-printing-compatible geometry and is monolithically integrated by exploiting high-precision Polyjet 3-D printing process. The manufactured antenna demonstrates good radiation patterns in a −10-dB impedance bandwidth from 28.8 to 37.0 GHz with in-band realized gains of 2.5–5.0 dBi.

A Modified Polygon Shaped Microstrip Patch Antenna Array for Ultra-Wideband Applications

A single element and two elements array polygon shape microstrip antenna is proposed and analyzed in this paper for ultra-wideband (UWB) applications. The technique used to improve antenna performance is etching rectangular slots on the patch of the antenna with different dimensions and positions. Two Polygon Shape antenna patches are introduced to enhance the antenna properties. Also, multi-slots are reached to improve the antenna gain, impedance matching sweep parameter optimization technique is used to all antenna parameters to enhance antenna properties. The dimensions of the single element antenna are 30 x 33 mm2 and consist of a slotted polygon patch printed on an FR-4 substrate. The proposed antenna has a resonant frequency of 6.2 GHz, while the dimensions of two elements antenna array are 60 x 33 mm2 and the resonance frequency is 9.8 GHz. A technique of inset feed transmission line was utilized to match the 50 Ω microstrip feed line and the radiating patch. These considerations make the structure is suitable for fifth-generation generation (5G) mobile wireless applications. The proposed antenna was simulated by use Computer Simulation Technology (CST-2020) software.

Improvement of Distance Protection with SVM on PV-Fed Transmission Lines in Infeed Conditions

Photovoltaic (PV) power plants have comparatively weak infeed characteristics, unlike conventional synchronous generators. The controllability of grid-connected inverters and the limited overcurrent capability of power electronic devices means that the characteristics of faults on transmission lines fed by PV power stations are substantially different than those on transmission lines fed by conventional sources. Operating performances of distance relays on PV-fed transmission line are unveiled. This paper analyses the impact of PV-fed transmission lines in infeed conditions on distance protection. Fault signals on the transmission line were generated by Digsilent PowerFactory software. Then, fault signals were analyzed by discrete Fourier transformation (DFT) with MATLAB software. The measured current and voltage signals were preprocessed first with DFT, and then machine learning via a support vector machine (SVM) was used for regression. This research proposes an improvement on distance protection with SVM for preventing maloperation in infeed conditions on PV fed transmission lines. The average accuracy was up to 95.6% in this study. The simulation was performed at different locations along the transmission line with different types of fault on a given power system model with the PV power plant.

A Compact Mu-Near-Zero Metamaterial Integrated Wideband High-Gain MIMO Antenna for 5G New Radio Applications.

This article demonstrates a compact wideband four-port multiple-input-multiple-output (MIMO) antenna system integrated with a wideband metamaterial (MM) to reach high gain for sub-6 GHz new radio (NR) 5G communication. The four antennas of the proposed MIMO system are orthogonally positioned to the adjacent antennas with a short interelement edge-to-edge distance (0.19λmin at 3.25 GHz), confirming compact size and wideband characteristics 55.2% (3.25-5.6 GHz). Each MIMO system component consists of a fractal slotted unique patch with a transmission feed line and a metal post-encased defected ground structure (DGS). The designed MIMO system is realized on a low-cost FR-4 printed material with a miniature size of 0.65λmin × 0.65λmin × 0.02λmin. A 6 × 6 array of double U-shaped resonator-based unique mu-near-zero (MNZ) wideband metamaterial reflector (MMR) is employed below the MIMO antenna with a 0.14λmin air gap, improving the gain by 2.8 dBi and manipulating the MIMO beam direction by 60°. The designed petite MIMO system with a MM reflector proposes a high peak gain of 7.1 dBi in comparison to recent relevant antennas with high isolation of 35 dB in the n77/n78/n79 bands. In addition, the proposed wideband MMR improves the MIMO diversity and radiation characteristics with an average total efficiency of 68% over the desired bands. The stated MIMO antenna system has an outstanding envelope correlation coefficient (ECC) of <0.045, a greater diversity gain (DG) of near 10 dB (>9.96 dB), a low channel capacity loss (CCL) of <0.35 b/s/Hz and excellent multiplexing efficiency (ME) of higher than -1.4 dB. The proposed MIMO concept is confirmed by fabricating and testing the developed MIMO structure. In contrast to the recent relevant works, the proposed antenna is compact in size, while maintaining high gain and wideband characteristics, with strong MIMO performance. Thus, the proposed concept could be a potential approach to the 5G MIMO antenna system.

Coplanar Discontinuous Transmission Line Feed for Phase Gradient Metasurface Antenna

The aim of this study is to efficiently excite the radiation of phase gradient metasurface (PGM), a novel coplanar discontinuous transmission line feed is proposed for reduction of the profile, where 12 uniform discontinuous rectangular rings form the feeding structure. The unit cells of PGM are symmetrically placed on both sides of this feed structure at the same layer, and they are close enough. The measurements agree well with those of simulations in the range of 10.48–11.18 GHz.

Circular array antenna with a transmission line to form a Yagi-Uda antenna for Wi-Fi

This paper describes the design of a Yagi-Uda stacked antenna array for 2.4 GHz applications. Its structure consists of 4 layers, layer 1 contains the active element, the reflector and the transmission line feed. Layers 2, 3 and 4 have circular patches that function as directors. The implementation of a "D" shaped patch on the active element is inserted, where the simulation results show that the proposed antenna can achieve a bandwidth that is much wider than the traditional circular patch antenna. Also the dimensions of the circular patch directors and their distances are chosen to have the highest directivity. The antenna simulation is performed in Ansoft Designer and Ansys HFSS 15.0 software.

A Low-Profile Compact Meander Line Telemetry Antenna with Low SAR for Medical Applications

A low-profile Compact Meander Line Telemetry Antenna (CMLTA) operating at 402.5 MHz for the Medical Implant Communication System (MICS) band medical applications is introduced. The proposed antenna focuses specifically on pacemaker telemetry applications. The meander line technique with an open loop configuration and simple transmission line feeding mechanism has been used for achieving the compact design. Based on the theory of surface current distribution, the proposed technique provides the opportunity to increase the electrical dimensions while decreasing the physical dimensions of the antenna. Further design optimization is carried out to optimize the overall antenna size to a maximum volume of 4080 mm3. By introducing CMLTA, the size of the antenna is reduced by 79% as compared to the previous work. The proposed antenna demonstrated satisfactory performance with 10 dB bandwidth of 6.17%, a maximum gain of -22 dBi and an EIRP of -25.28 dBi. The analysis of Specific Absorption Rate under premise use of 1 W input power provided the maximum 1 g and averaged 10 g SAR of 74.7 W/kg and 17.7 W/kg, respectively, demonstrating a satisfactory level according to the IEEE standard safety guidelines. Fabrication and measurements are carried out where measured results are found to be in good agreement with the simulated results. With the optimized dimensions, satisfactory gain, EIRP, and SAR performance, the proposed CMLTA is deemed suitable for pacemaker telemetry applications for effective communication.

Measurement of the ICRH antenna phasing using antenna strap probe based diagnostic system in EAST tokamak

To operate the ion cyclotron resonance heating (ICRH) antennas in a better heating state and produce relatively low impurities, it is necessary to control the antenna spectrum by changing the antenna phasing. As the electrical length of the antenna feeding transmission lines is changing as a matter of the standing wave pattern at the ceramic supports, 90° elbows, T-connectors and antenna loops, we chose to measure the current at the grounding points of the antenna loops by antenna strap probe. The voltage drops along a small, several millimeter-long paths at the end of the antenna loops give a signal that is proportional to the current in the antenna loop. Through the simulation of the antenna strap probe and the actual measurement of the antenna phasing under vacuum conditions, the reliability of the antenna strap probe based diagnostic system have been successfully proved. Moreover, this system was successfully applied to the ICRH daily experiments in the spring of 2021. In the near future, the active real-time feedback control of the antenna phasing system will be developed based on this diagnostic system in the EAST tokamak.

Metamaterial inspired LPDA MIMO array for upper band 5G applications

In this paper, an enhanced upper band 5G multiple-input multiple-output (MIMO) array is presented. The proposed array is based on a wide band LPDA antenna loaded with epsilon near zero (ENZ) index metamaterial. The metamaterial cells result in more than 3 dBi gain enhancement. In addition, multiples metamaterial cells arrangements are studied including straight, concave, and convex rows. The array covers a wideband of MMW frequencies extending from 26 up to 39 GHz. The LPDA antenna element design consists of alternating five arms printed on RO5880 substrate. All of the dipole arms are uniformly placed along parallel microstrip feeding transmission lines on both sides of the substrate. The main feeding line is placed over a partial ground plane at the backside of the substrate. The MIMO-LPDA array exhibits stable radiation characteristics over the operating band. A maximum realized gain of 11 dBi is achieved at 36 GHz for a single element radiator. In addition, essential MIMO performance indicators such as Envelope Correlation Coefficient (ECC), Diversity Gain (DG), and Channel Capacity Loss (CCL) are examined and determined to fulfill the needed standard of ECC, DG, and CCL. The fabricated prototypes of both the single antenna element and the MIMO array show very good agreement with simulated results.

Design of circular-shaped microstrip patch antenna for 5G applications

Using circular geometry has a great influence on many fields of science and engineering, one of which is antenna. Communication systems were oriented towards fifth generation (5G) because of large- bandwidth systems, compact requirements, high-data rates. In this research, a design and simulation are made to a microstrip circular patch antenna. The patch has two circles a compact structure of the first circle radius is 2.5 mm and second circle radius is 1 mm with thickness 0.35 mm. The proposed antenna has three resonant frequencies 41.08 GHz with a return loss of -12.4 dB, 47.4 at -18.86 dB and 54.4 at return loss -24.3 dB. The bandwidths are 150 MHz, 222 MHz and 219 MHz, the gains of three resonant frequencies are 6.16 dB, 9.89 dB and 5.54 dB, with efficiency of 98%. A technique of inset feed transmission line was utilized to match the fifty Ω microstrip feedline and the radiating patch. Based upon the proposed design, a Roger RT Duroid 5880 substrate that possesses loss tangent of 0.0009 with a height of 0.5 mm and a dielectric constant of 2.2 is employed. A computational process is conducted and analyzed by the use of computer simulation technology microwave studio.

Design of a Novel Split-Bowtie Slotted Multi-Resonant Antenna

This article demonstrates a novel design of a split-bowtie slotted multi-resonant antenna. The design process was inspired from previous research of integrating a slot of a similar profile to the outer boundary of a rectangular patch antenna. The followed approach presents steps of proposed antenna evolution, which starts with a bowtie-shape slotted antenna and a coaxial feed to a final design with a split-bowtie-shaped slot, and a double transmission line feed. Polar dimensions of the outer boundary (radii and angle) and slot profiles together with the dimensions of the feed, whether coaxial or transmission line, were considered as parameters for optimization. Four antennas were accordingly studied, which led to the final split-bowtie-shaped antenna IV. These designs were performed utilizing a special simulation package called "CST Microwave Suite" that included the optimizer "Genetic Algorithm". The final design offers 4 simultaneous bands from a single split-bowtie-shaped slot; a big advantage of unnecessary integration of a set of complicated slots on front and ground planes. Further, the antenna finds applications in mobile GSM and LTE bands 900/1800 MHz and 2.1 GHz, together with the satellite communications band 1.25 GHz. It is therefore simple, non-reconfigurable, easy to fabricate, designed on a single copper layer, with a low cost FR4 substrate and a plane copper ground.

MIMO Antenna Design and Optimization with Enhanced Bandwidth for Wireless Applications

This paper demonstrates a compact MIMO (Multi Input Multi Output) fractal type antenna for ultra-wide band applications. The proposed antenna is manufactured on a lowcost substrate material and the design is analyzed for various iterations in terms of reflection coefficient, gain, and bandwidth. The 50 Ω transmission line feed is used for both fractal patches and a metamaterial structure is used as the ground plane. The proposed design achieved a wide-band frequency response between 5.8 and 15 GHz, with the reflection coefficient of less than –10 dB. Reduced mutual coupling, positive gain and stable radiation patterns were observed throughout the operating band as well. The bandwidth of 9.2 GHz is achieved with the use of a metamaterial structure on the ground plane. The ECC and diversity gain obtained prove the excellent diversity performance of the antenna. The design was simulated using HFSS software and was tested in a lab.