Ultra-wideband Dipole Research Articles

An Ultra-Wideband Integrated Filtering Antenna with Improved Band-Edge Selectivity Using Multimode Resonator

In this paper, a novel design of ultra-wideband (UWB) filtering antenna integrated with the multimode resonator (MMR) bandpass filter is proposed, aiming to enhance band-edge selectivity. At the beginning, a MMR bandpass filter is modified and studied. Based on the classic MMR filter, the proposed filter folds the microstrip transmission line to reduce its size while retaining the original filtering performance. Moreover, an open stub and short stub are added to the proposed filter to obtain a transmission of zero. Then, the folded filter with stubs and a UWB bow-tie antenna are integrated together to form a filtering antenna. The open stub and short stub in the MMR structure enhance the antenna’s upper and lower band-edge selectivity, respectively. Series of parameters are studied to analyze their influences on the frequency selection range and band-edge characteristics. Compared with the original UWB dipole antenna, such an integrated approach brings many benefits. Firstly, the UWB filter not only broadens the bandwidth of the device, but also improves band-edge selectivity, which can eliminate the unwanted passband near the operating frequencies. Secondly, the integrated system reduces the size and cost of the devices, which is very important in the miniaturization of wireless systems. In this research, the reflection coefficient (S11) of integrated filtering antenna is lower than −10 dB between 2.92 and 11.51 GHz, and it has a fractional bandwidth of 119%. The measured shape factor is 1.027 (very close to 1), which proves that this design has a better band-edge selectivity. Simultaneously, good radiation characteristics are also attained, with a maximum realized gain of 6 dBi. Theoretical simulation results are similar to the experimental results. The measurement results of the manufactured device effectively validate that its performances have reached the simulation design requirements.

A General Optimization Method for Complex Requirements Antenna Based on Balanced Demotion MOEA

A general Multi-objective evolutionary algorithm (MOEA) is presented to solve the antenna optimization problem with complex requirements. By analyzing the common requirements in the antenna design process, a strategy of calculating the difference between the indicator value and the threshold is applied to construct the objective units that can accurately evaluate the antenna performance and reconstruct the objective functions quickly. The fitness functions can solve the fuzzy requirements problem. An adaptive mechanism is designed for mutation and crossover operation in order to balance the convergence rate and the ability to avoid local extremes. In non-dominated sorting, the crowding calculation method is improved so that the individuals can be dispersed in the objective space. A demotion mechanism is designed for the selection operation to balance the importance of all objective functions and constraints. It can not only make the optimal solution closer to the actual requirement but also reduce the computation cost of the algorithm itself. Then this algorithm is applied to an ultra-wideband (UWB) dipole antenna with complex requirements as a case study. Analyzing the optimization results shows that all the indicators of the antenna optimized by the algorithm can well satisfy the actual requirements.

Microwave Catheter Navigation System for the Radiofrequency Liver Ablation.

Thermal ablation is a well-known method used in interventional radiology to treat cancer. The treatment success is closely related to the exact catheter location in the treated area. Current navigation methods are based mostly on ultrasound or computed tomography. This work explores the possibility of tracking the catheter position during ablation treatment of hepatocellular carcinomas (HCC) using an ultra-wideband (UWB) antenna array and microwave radar imaging based on the "Delay and Sum" (DAS) algorithm. The feasibility was first numerically studied on a simple homogeneous liver model. A heterogeneous anthropomorphic 3D model of the treated region consisting of the main organs within the treated area was then used. Various standard radiofrequency ablation (RFA) catheters were placed virtually in the heterogeneous model. The location and orientation of the antenna elements of the developed imaging system and the applied frequency band were studied. Subsequently, an experimental setup consisting of a 3D printed homogeneous anthropomorphic model, eight UWB dipole antennas, and catheters was created and used in a series of measurements. The average accuracy determining the catheter position from simulated and experimental data was 3.88 ± 0.19 and 6.13 ± 0.66 mm, which are close to the accuracy of clinical navigation systems.

A Band-Notched Antenna With Two Radiation Zeros Using Grounded Coplanar Waveguide Filter for 2.4/5 GHz WLAN Applications

In this article, a band-notched dual-polarized crossed dipole antenna is proposed for 2.4/5 GHz WLAN applications. The proposed antenna works on the WLAN 2.4-GHz (2.4–2.48 GHz) and 5-GHz (5.15–5.85 GHz) bands for a VSWR <2 with two radiation zeros within 3.4–3.6 GHz. First, an ultra-wideband crossed dipole antenna with an operating frequency of 2.4–5.8 GHz is designed using the grounded coplanar waveguide (GCPW) feeding structure. Second, a miniaturized defected microstrip structure (DMS) is embedded in the GCPW feeding strip to form a stopband behavior with a radiation zero. Finally, combining with the design of a C-shaped split ring resonator (SRR) on the arms of the dipole antenna, a band notch (3.4–3.6 GHz) with two radiation zeros can be realized. These two radiation zeros can be adjusted independently to achieve a wide stopband performance. As a result, compared with the original ultra-wideband dipole antenna, the realized gains of the proposed antenna in the 3.4–3.6 GHz range are all suppressed from 8 dBi to less than −8 dBi. The proposed antenna can realize the stable unidirectional radiation pattern and a high gain of around 7 dBi in the lower band and 8.5 dBi in the higher band of WLAN. As a demonstration, the proposed antenna is fabricated and measured, and the measurement results are in good agreement with the simulation results.

Implementation of Metamaterial Loading to Miniaturized UWB Dipole Antenna for WLAN and WiMAX Applications with Tunability Characteristics

This paper presents a double-printed circular slot inscribed, hexagonal shape miniaturized dipole antenna featuring the ultra-wideband (UWB) characteristics with the implementation of linearly tapered feedline. The miniaturized UWB dipole antenna is designed for wireless applications wireless local area network (WLAN) and WiMAX by introducing a proposed metamaterial unit cell. Further, in comparison with the conventional UWB dipole antenna, miniaturization is achieved up to 35.89% and 16.67% with respective active patch area and antenna volume, respectively. The electrical dimension of the proposed antenna is 0.299 λ × 0.4385 λ × 0.0159 λ, of course, at lower frequency of 2.99 GHz. The use of metamaterial rectangular split-ring resonator and slotted ground structure witnessed the band achievements for wireless standards WLAN and WiMAX. The proposed structure is fabricated on FR4 substrate and tested. Impedance bandwidth of proposed antenna is obtained about 7.26% (2.39–2.57 GHz), 25.23% (2.91–3.75 GHz), and 16.92% (4.87–5.77 GHz) under simulation and 11.49% (2.38–2.67 GHz), 24.48% (2.94–3.76 GHz), and 15.99% (4.95–5.81 GHz) in measurement for WLAN (2.4–2.5, 5.150–5.250, and 5.725–5.825 GHz) and WiMAX (3.3–3.8 GHz) bands, respectively. Tunability between the wireless standards is demonstrated with the help of PIN diodes. The proposed design achieved high average gain of 3.31 and 2.06 dBi for simulation and measurement, respectively. The peak average radiation efficiency of 82.9% is observed during measurement mode. Experimental results are in good agreement with those obtained in the simulation of the proposed antenna.

Ultra-Wideband Dual-Polarized Antenna With Three Resonant Modes for 2G/3G/4G/5G Communication Systems

In this paper, a compact dual-polarized ultra-wideband dipole antenna is realized by exciting three resonant modes using double-loop (DL) dipoles with stepped exponential-shaped (ES) arms. First, a single-loop (SL) crossed dipole antenna using the modified direct feeding (MDF) structure with ES arms is designed and analyzed to achieve wide bandwidth (1.7–2.7 GHz) with two resonant modes. Second, without increasing the volume of the antenna, one more loop is employed to gain one more resonant mode to enhance the bandwidth into 1.68–3.7 GHz and fractional bandwidth (FBW) up to 75% for VSWR < 1.5. In order to adjust three resonant modes independently, the ES arms of the DL dipole antenna are designed in stepped shapes. The HPBW is 65–70° for 1.7–2.7 GHz (2G/3G/4G) and 95° for 3.4–3.6 GHz (5G). In addition, the proposed antenna can also be designed with a bandwidth of 2.38–6.42 GHz (FBW of 92%) for VSWR < 2, occupying WLAN/4G/5G. As demonstrations, the proposed antennas covering 1.68–3.7 GHz for VSWR < 1.5 (Antenna A) and 2.38–6.42 GHz for VSWR < 2 (Antenna B) are designed, fabricated and measured, and the measured results agree well with the simulations.

Ultrawideband dipole receiving antenna for measuring short pulses with extended bandwidth

AbstractThis article presents the design of an ultrawideband active integrated antenna based on an electric dipole and the results of its testing. The antenna is intended to perform low‐distortion measurements of the instantaneous electric field strength of short pulses whose spectra lie within the frequency range from 0.05 to 3 GHz. The antenna is fabricated using the technology of printed circuit boards on a 1‐mm thick FR4 plate of dimensions 60 × 28 mm. It has a built‐in balancing‐to‐unbalancing unit and an unbalanced output. The difference in output voltage pulse waveform between the proposed antenna and a reference TEM‐antenna is insignificant.

A triple-band dipole antenna for UMTS/LTE and UWB applications

ABSTRACTIn this paper, an ultra-wideband (UWB) dipole antenna with integrated Universal Mobile Telecommunications Service and long-term evolution 2.5 GHz band has been presented. The design process involves loading L-shaped and meandered line slots on UWB dipole antenna for achieving triple-band characteristics. The proposed antenna offers a small electrical size of 0.18λo * 0.23λo * 0.01λo with impedance bandwidths (|S11| < −10dB) of 11%, 6.5% and 127.7% centred at 2 GHz, 2.6 GHz and 10.8 GHz, respectively. The designed antenna shows good radiation characteristics with appreciable gain and omnidirectional radiation patterns over the operating bandwidth with satisfactory time domain performance. A prototype has been fabricated and tested in order to validate the simulation results.

Microstrip to Parallel-Strip Nonlinear Transition Balun with Stubs and DGS for UWB Dipole Antenna

Three tapered baluns with nonlinear transition are developed for harmonic suppression in dipole antenna. The first balun consists of an exponential profile with the size of a quarter–wavelength for both the height and width with a wideband characteristic. However, for some applications such as narrowband harmonic suppression antennas and wideband-to-narrowband reconfigurable antennas, the suppression of higher operating band is desired. By employing stubs-filter and a defected ground structure (DGS), two narrowband tapered baluns are produced. They are named as an exponential balun-stub and an exponential balun-DGS, respectively, that operate from 1 to 2 GHz. A simulated and measured results that based on the reflection coefficient is found to be better than -10 dB from 1 to 2 GHz. The employment of the stubs and DGS have enabled these baluns to have the capability to reject the unwanted higher frequency band from 2.0 to 10 GHz. Finally, the proposed baluns are employed as a feeding circuit for an ultra wideband (UWB) circular dipole antenna that produces a reasonable outcome.

A Simple Ultra-Wideband Magneto-Electric Dipole Antenna With High Gain

AbstractA simple ultra-wideband magneto-electric dipole antenna utilizing a differential-fed structure is designed. The antenna mainly comprises three parts, including a novel circular horned reflector, two vertical semicircular shorted patches as a magnetic dipole, and a horizontal U-shaped semicircular electric dipole. A differential feeding structure working as a perfect balun excites the designed antenna. The results of simulation have a good match with the ones of measurement. Results indicate that the designed antenna achieves a wide frequency bandwidth of 107 % which is 3.19~10.61 GHz, when VSWR is below 2. Via introducing the circular horned reflector, the designed antenna attains a steady and high gain of 12±1.5dBi. Moreover, settled broadside direction main beam, high front-to-back ratio, low cross polarization, and the symmetrical and relatively stable radiation patterns in the E-and H-plane are gotten in the impedance bandwidth range. In the practical applications, the proposed antenna that is dc grounded and has a simple structure satisfies the requirement of many outdoor antennas.

An Ultrawideband Dipole With a Director as a Feed for Reflector Antennas

A novel ultrawideband directional flat dipole capped by a planar director is proposed in this letter. The novelty of the antenna is the great improvement of the bandwidth of a flat dipole above an ordinary finite ground plane by using a simple parasitic top patch, referred to as the director. A linearly polarized prototype has been designed and manufactured, and achieved a nearly 3:1 operating bandwidth (2.2-6.5 GHz) with a return loss higher than 10 dB, nearly constant radiation patterns, and high aperture efficiency over the entire operating band.

A high-gain inkjet-printed UWB LPDA antenna on paper substrate

An ultra-wideband (UWB) log-periodic dipole array (LPDA) antenna inkjet-printed on a 0.5 mm thick photo paper substrate is presented. The overall size of the LPDA antenna is 130 × 60 mm2. The LPDA antenna exhibits stable input-impedance characteristics and a consistent end-fire radiation pattern over the whole operating band of 2.2–11 GHz. Fulfilling the need of high-gain flexible antennas for UWB, a highly directive measured gain of 9.5 dBi on a paper substrate makes it an excellent candidate for flexible wireless devices.

Design of a Planar UWB Dipole Antenna With an Integrated Balun Using Surrogate-Based Optimization

A design of an ultrawideband (UWB) antenna with an integrated balun is presented. A fully planar balun configuration interfacing the microstrip input of the structure to the coplanar stripline (CPS) input of the dipole antenna is introduced. The electromagnetic (EM) model of the structure of interest includes the dipole, the balun, and the microstrip input to account for coupling and radiation effects over the UWB band. The EM model is then adjusted for low reflection over the UWB band by means of fast simulation-driven surrogate-based optimization. This approach allows us to obtain the final design at low computational costs and at a high-fidelity level of structure description. Measurements of the manufactured optimal design validate the use of the balun as well as the design approach.

Frequency domain analysis of UWB dipole arrays

In this paper, behavior of dipole arrays for Ultra-Wideband (UWB) signals is investigated using an approach in the frequency domain. Energy formulas and correlation coefficient expressions are derived for an array of thin dipoles at the transmitting side and one dipole at the receiving side. Beam-scanning characteristics of UWB dipole arrays are also investigated in the same manner. Different element lengths are used in the array to improve the detection and beam-scanning capabilities. Derived frequency domain expressions can easily be evaluated numerically, allowing us to obtain reasonably accurate results. This approach which is an alternative to numerical methods in time domain serves as a different viewpoint and will be a significant step to make progress in UWB antenna design.

On the Approximation of the UWB Dipole Elliptical Arms With Stepped-Edge Polygon

A simple method of approximation of the elliptical patch with stepped-edge polygon is proposed as an introduction to wider studies over the planar ultrawideband (UWB) antennas. The general idea is to replace the elliptical patch with an equivalent polygonal patch, with minimum loss in the performance. The principles of the proposed method are presented in this letter, as well as the results of performed numerical studies and its experimental verification. A satisfying level of agreement of the parameters of the original antenna and its stepped-edge polygon version indicates that the proposed approximation can be applied without important loss of antenna performance.

On the Performance of Printed Dipole Antenna With Novel Composite Corrugated-Reflectors for Low-Profile Ultrawideband Applications

An investigation of the performance of printed dipole antenna with finite periodically corrugated-reflectors for low-profile ultrawideband (UWB) applications is presented. According to the relative orientations of the linear-polarized source antenna and the corrugated-reflectors, the problem could be divided into H and E cases. Their fundamental differences and design guidelines are discussed in detail. A novel composite corrugated-reflector based on the combinations of H-type and E-type ones is proposed for the first time, and fully characterized with a UWB source dipole which was optimized in the free space for better comparisons. An example antenna with only 21 mm core profile, composed of a printed UWB dipole, a microstrip balun and a composite corrugated-reflector, has an impedance bandwidth of 2.75 GHz to 8.35 GHz. Both numerical and experimental results show that the example antenna also has stable uni-directional radiation patterns and a realized gain of over 6 dB within the frequency band from 2.3 to 6.0 GHz, which could be a decent alternative to the EBG antennas due to significant improvements on pattern and gain bandwidth.

A UWB Dipole Antenna With Enhanced Impedance and Gain Performance

A planar dipole antenna is proposed with enhanced impedance and gain performance across an ultrawideband (UWB) operating bandwidth of 3.1-10.6 GHz. The proposed antenna consists of two semi-elliptical-ended arms connected by a shorting bridge. With the shorting bridge, the length of the antenna is reduced and the radiation performance in terms of gain is improved especially at higher frequencies. The performance of the proposed antenna is validated experimentally using a wideband balun to realize the microstrip-co-planar strip transition. The results show that the proposed antenna can achieve a gain of 2.4-6.2 dBi across a VSWR=2 impedance bandwidth of 118% (2.8-10.9 GHz). The time domain responses of pulsed UWB signals through conventional and proposed antennas are compared. Furthermore, a parametric study is performed to provide antenna engineers with the information about the design.

DESIGN OF A PLANAR UWB DIPOLE ANTENNA WITH BAND-NOTCHED CHARACTERISTIC

A compact planar ultra-wideband (UWB) dipole antenna having band-notched characteristic is presented. The dipole antenna has the shape of a modifled annular ring and is fed by a 50-› microstrip line. Cutting a slot in each radiating annular ring improves the input impedance bandwidth. With the design, the return loss is lower than i10dB in 3.1GHz{10.6GHz frequency range. In addition, band- notched flltering properties in the 5.15GHz{5.825GHz are achieved by etching four rectangular slits in the ground plane, and the radiation pattern is similar to a conventional dipole antenna. A good agreement is found between the simulation and the experiment. Details of the proposed antenna design and the experimental results are presented.

Compact dielectric resonator antenna for microwave breast cancer detection

A compact stair-shaped dielectric resonator antenna (DRA) is designed and fabricated for microwave breast cancer detection. A quarter-wavelength choke was incorporated to reduce the finite ground plane size. A more than 40% return loss of 10 dB centred at 6.5 GHz is achieved with a 50 Ω coaxial port. Parametric studies are carried out to provide practical insights into sensor design. The design is performed numerically and confirmed experimentally. A simple model for the tissue is considered and the interaction of the sensor with the tissue is investigated. Good matching is retained without adding any matching medium or lumped loads when the sensor is in contact with the tissue. A two-element sensor array is investigated numerically. A dipole antenna and a circular ultra-wideband dipole antenna are compared with the stair-shaped DRA with a choked ground plane. Preliminary results are obtained for the cases with different tumour locations. The DRA type of sensor reveals good potential for frequency-domain detection.

Lumped-Element Balun for UHF UWB Printed Balanced Antennas

A semi-lumped balun transformer for UHF and ultrawideband (UWB) dipole antennas is presented in this paper. The proposed structure is based on two asymmetric filters that also transform the variable antenna impedance into the desired source impedance. These asymmetric filters make use of a binomial impedance transformer in each filter section. The asymmetric filters (one low pass filter, LPF, and other high pass filter, HPF) allow the balun bandwidth to be increased while the binomial transformer matches the variable balanced dipole impedance. In this way the ripple in the balun response due to the variation of the UWB dipole impedance is reduced. A balun for a UHF and UWB dipole antenna working from 220 to 820 MHz (bandwidth of 4:1) has been achieved with losses lower than 1 dB. These types of baluns are particularly useful in the low microwave frequency band.