Quarter-wave Monopole Research Articles

Multi-objective hybrid split-ring resonator and electromagnetic bandgap structure-based fractal antennas using hybrid metaheuristic framework for wireless applications

Design closure and parameter optimisation are crucial in creating cutting-edge antennas. Antenna performance can be improved by fine-tuning preliminary designs created using theoretical considerations and rough dimension adjustment via supervised parameter sweeps. This paper introduces a frequency reconfigurable antenna design that can operate at 28/38 GHz frequencies to meet FCC and Ofcom standards for 5G applications and in the 18 GHz frequency band for K-band radar applications. A PIN diode is used in this design to configure multiple frequency bands. The antenna has a modified rectangular patch-like structure and two optimised plugins on either side. The study that is being presented focuses on maximising the parameters that are subject to optimisation, including length (Ls), width (Ws), strip line width (W1), and height (ht), where the antenna characteristic parameters such as directivity is tuned by a hybrid optimisation scheme called Elephant Clan Updated Grey Wolf Algorithm (ECU-GWA). Here, the performance of gain and directivity are optimally attained by considering parameters such as length, width, ground plane length, width, height, and feed offsets X and Y. The bandwidth of the proposed antenna at − 10 dB is 0.8 GHz, 1.94 GHz, and 7.92 GHz, respectively, at frequencies 18.5 GHz, 28.1 GHz, and 38.1 GHz. Also, according to the simulation results, in the 18 GHz, 28 GHz, and 38 GHz frequencies S11, the return loss is − 60.81 dB, − 56.31 dB, and − 14.19 dB, respectively. The proposed frequency reconfigurable antenna simulation results achieve gains of 4.41 dBi, 6.33 dBi, and 7.70 dBi at 18.5 GHz, 28.1 GHz, and 38.1 GHz, respectively. Also, a microstrip quarter-wave monopole antenna with an ellipsoidal-shaped complementary split-ring resonator-electromagnetic bandgap structure (ECSRR-EBG) structure has been designed based on a genetic algorithm having resonating at 2.9 GHz, 4.7 GHz, 6 GHz for WLAN applications. The gain of the suggested ECSRR metamaterial and EBG periodic structure, with and without the ECCSRR bow-tie antenna. This is done both in the lab and with numbers. The measured result shows that the ECSRR metamaterial boosts gain by 5.2 dBi at 5.9 GHz. At 5.57 GHz, the two-element MIMO antenna achieves its lowest ECC of 0.00081.

Design and analysis of a 2.4 GHz whip antenna for tyre pressure monitoring system

This paper presents the performance analysis of a quarter-wave monopole antenna radiating at a frequency of 2.4 GHz. Two antenna models were proposed. The whip monopole antenna (WMA) at length l-equal to λ / 4 , and the improved whip monopole antenna (IWMA) at a length slightly less than λ / 4 . To get the IWMA, the length of the antenna was gradually reduced by a factor of 0.25 mm until the optimum length of the antenna was achieved. The antennas were modelled and analyzed using a 3D electromagnetic solver known as HFSS. Simulation results show that the IWMA has excellent performance over the WMA. The WMA resonated at 2.3 GHz, with a reflection coefficient of -12.36 dB, a VSWR of 1.65, an impedance bandwidth of 2.17–2.47 GHz and a gain of 5.9 dB. But by slightly reducing the length of the monopole antenna, the IWMA resonated at 2.4 GHz. The reflection coefficient of the IWMA was 1.99 dB better than the WMA. The IWMA had a wider impedance bandwidth than the WMA. It was only in the antenna gain that the WMA was better. The IWMA can function as a tyre pressure monitoring system (TPMS) antenna because it is compact and have excellent antenna parameters.

A Frequency-Reconfigurable Filtenna for GSM, 4G-LTE, ISM, and 5G-Sub 6 GHz Band Applications.

This paper presents the design and realization of a flexible and frequency-reconfigurable antenna with harmonic suppression for multiple wireless applications. The antenna structure is derived from a quarter-wave monopole by etching slots. Afterward, the high-order unwanted harmonics are eliminated by adding a filtering stub to the feedline to avoid signal interference. Lastly, frequency reconfigurability is achieved using pin diodes by connecting and disconnecting the stubs and the rectangular patch. The antenna is fabricated on the commercially available thin (0.254 mm) conformal substrate of Rogers RT5880. The proposed antenna resonates (|S11| < –10 dB) at five different reconfigurable bands of 3.5 GHz (3.17–3.82 GHz), 2.45 GHz (2.27–2.64 GHz), 2.1 GHz (2.02–2.29 GHz), 1.9 GHz (1.81–2.05 GHz), and 1.8 GHz (1.66–1.93 GHz), which are globally used for 5G sub-6 GHz in industrial, medical, and scientific (ISM) bands, 4G long-term evolution (LTE) bands, and global system for mobile communication (GSM) bands. The simulated and measured results show that the antenna offers excellent performance in terms of good impedance matching with controllable resonant bands, high gain (>2 dBi), stable radiation patterns, and efficiency (>87%). Moreover, the conformal analysis shows that the antenna retains its performance both in flat and bending conditions, making it suitable for flexible electronics. In addition, the antenna is compared with the state-of-the-art works for similar applications to show its potential for the targeted band spectrums.

Performance Limits of 433 MHz Quarter-wave Monopole Antennas due to Grounding Dimension and Conductivity

Among antennas for Industrial, Scientific and Medical (ISM band) applications at 433 MHz, quarter-wave monopole is a reasonably good trade-off between size, gain, and cost. The electrical performance of the monopole is largely dependent on the quality of the ground plane (size and conductivity), which exhibits a practical limit on the achievable gain as most industrial user environments can provide only a finite ground plane of finite electrical conductivity. Establishing traceability in understanding the performance degradation due to such limits due to the grounding dimension and conductivity is becoming mandatory. To this end, this work leverages universal MATLAB in place of off-the-shelf software (HFSS or CST) for the quarter-wave monopole antenna simulation at 433 MHz parametrised with the ground plane’s dimension with respect to the wavelength (λ). Results indicate that by enlarging the ground plane’s size from 0.14 λ to 14 λ, the gain (directivity for PEC) from the 3D radiation pattern rises from 1.79 dBi, then starts levelling off at 6.7 dBi (5.78 λ), until saturating at 7.49 dBi (13 λ). The radiation efficiency and gain of various grounding conductivity scenarios (e.g., gold, aluminium, steel) are also quantified to inform antenna designers and engineers for commercial, industrial, defence and space applications.

GROUND MODIFIED ELECTRICALLY SMALL ANTENNA FOR DCS 1800 APPLICATIONS

A Uni-planar coplanar waveguide fed modified ground radiating structure with very compact size and simple structure, suitable for Global System for Mobile 1800 DCS application is discussed. Developed antenna offers a 2:1 VSWR bandwidth of 180 MHz ranging from 1.71 GHz to 1.89 GHz which is wider to cover both uplink and downlink bands of GSM1800. Antenna possesses linear polarization characteristics and offers a radiation pattern just like a quarter wave monopole. Developed antenna offers an average and uniform gain of 2.1 dBi with a moderate gain of 79.8% in the entire band of operation.

The estimate of directional characteristics of a near-surface vertical quarter-wave monopole in the high frequency range at different stages of soil moisture evaporation

The estimate of directional characteristics of a near-surface vertical quarter-wave monopole in the high frequency range at different stages of soil moisture evaporation

Small Split-Ring Resonators as Efficient Antennas for Remote LoRa IOT Systems-A Path to Reduce Physical Interference.

While wireless IOT modules can be made extremely compact, antennas typically protrude from the module, providing the potential to catch near moving/rotating equipment or transfer loads to the PCB through end forces, which can lead to failures. This work explores the use of split-ring resonator (SRR) designs to achieve a planar antenna with a maximum dimension less than a monopole working at the same frequency. The very narrow bandwidth of the SRR required detailed physical models to create printed circuit board (PCB)-based antenna designs that could be used at LoRa frequencies of 433 MHz and 915 MHz. Uncertainty analysis allowed for the impact of geometrical and physical tolerances on the resonant frequency to be evaluated. Nearfield and farfield measurements were performed allowing for the resonant frequency, directionality, and range of the antenna to be evaluated. An unbalanced SMA port was added to the SRR design to allow for the use of a network vector analyser to determine the input impedance of various designs. The optimum design achieved an input resistance of 44 Ω at a resonant frequency of 919 MHz, close to the target values (50 Ω at 915 MHz). Field measurements of the received signal strength from a planar antenna design indicated a gain of 5 dB over a conventional quarter-wave monopole antenna, in a footprint that was 40% smaller than the monopole.

A Novel Ultrawideband Gear-Shaped Dielectric Ring Resonator Antenna

In this study, a novel ultrawideband (UWB) dielectric ring resonator (DRR) antenna has been proposed. DRR antennas include a single monopole antenna in the center of a ground plane and a dielectric with a symmetric structure around the monopole. This structure will lead to ultrawide band antenna. However, it is still possible to enhance the antenna bandwidth. In this study, we combine the DRR structure with an array antenna. The proposed antenna includes a circular array of four triangle resonators, which is rotated around the center of the triangle base to form a gear-shaped ring resonator antenna. In this design, characteristics of all these antennas are combined to enhance the antenna bandwidth including triangular dielectric resonator, circular array antenna, dielectric ring resonator structure, and a quarter-wave electric monopole. Triangular dielectric resonator antennas are wideband and in small size. Ring resonator antennas are inherently ultrawideband. Quarter-wave electric monopole and circular array structure can also enhance antenna bandwidth. This novel shape of the DRR antenna possesses the wider impedance bandwidth compared to similar works. Impedance bandwidth is 150% (5.2–36.1 GHz), and the bandwidth ratio is 1 : 6.9, which is much greater than earlier reports.

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.

The CanX-7 ADS-B Mission: Signal Propagation Assessment

The CanX-7 Automatic Dependent Surveillance-Broadcast (ADS-B) nanosatellite mission collected more than four million ADS-B messages between October 2016 and April 2017. An analysis of data collected over the north Atlantic Ocean from 05 to 28 Oct included 20,707 position messages in which the angle from satellite nadir to aircraft was determined. The proximity of the received signal strength to the noise floor of the sensor allowed for an analysis of optimal aircraft-satellite orientation for ADS-B transmission detection. The results showed a significant disparity between descending and ascending passes of the satellite. For descending passes, the average nadir angle was 50.1° with 90% of the contacts greater than 40°. The ascending passes had an average nadir angle of 31.6° with only 24.8% of the contacts exceeding 40°. The evidence suggests that the satellite magnetic torquer may not have been fully aligned with the north magnetic pole as the satellite moved northward, resulting in ascending pass nadir angles that were not reflective of the full range of values. Further analysis of the descending passes showed agreement with an ADS-B signal propagation model with peak reception at nadir angles of 51° ± 8°. For space-based ADS-B operations, the results support the replacement of the current aircraft upper quarter-wave monopole to an antenna that will transmit more energy directly above the airframe.

Tripple-Band Microstrip Antenna for Wireless Application

This paper proposes a tripple-band microstrip antenna. The proposed antenna is designed to operate at Bluetooth (2.4–2.485 GHz), WiMAX (3.3–3.7 GHz) and WLAN (5.15–5.35 GHz, 5.725–5.825 GHz) bands. The antenna consists of a straight microstrip feed line and an inverted assymetric T shaped slot at ground plane. The microstrip feed line acting as quarter wave monopole is responsible for obtaining WiMAX band and the slot of ground plane is responsible for obtaining Bluetooth and WLAN band. The simulated and measured results have good agreement.

Small antenna design for very compact devices and wearables

In this study the authors present a possible solution for a compact printed folded dipole antenna, designed to match an nRF51822 Bluetooth Smart device. The use of a differential design avoids the need for a balun and the matching network between the IC and the antenna, therefore, reducing the power loss in these components. The performance of the proposed printed dipole is compared with the standard application of a quarter-wave monopole antenna as proposed by the manufacturer and a commercial ceramic antenna. It is shown that the proposed design presents better radiation properties than the other two approaches, which resulted in an increased communication range of the system by 50%. Measurements are compared with simulation to attest the validity of the authors’ proposal.

A Multiband Multiple-input Multiple-output Antenna System for Long Term Evolution and Wireless Local Area Networks Handsets

A novel multiband multiple-input-multiple-output (MIMO) antenna system is proposed. The MIMO antenna system consists of two antenna elements, each of which comprises of three radiators: a driven monopole, an S-shaped strip and an inverted F-shaped strip and occupies footprint of 15x18.5x0.8 mm3 only. The driven monopole acts as a quarter-wave monopole and stimulate higher mode resonance. The two strips are excited by electromagnetic coupling from the driven monopole and serve as two additional monopoles leading to a wideband performance for the lower band. The bandwidths (VSWR ≤ 2.75) achieved for the antenna element are 1.67 – 2.2 GHz for the lower band and 2.28 –2.95 GHz for the upper band which cover LTE-1, LTE- 2, LTE- 3, LTE- 7, LTE- 40 and WLAN 2.4 GHz bands. A T-shaped slot and another two slots are introduced to reduce the coupling effect between the two multiband antenna elements. The isolation achieved is higher than 18 dB over the whole band, leading to an envelope correlation coefficient of less than 0.01. Furthermore, the diversity characteristics of mean effective gains (MEGs) and diversity gain (DG) are also studied. Both the simulated and measured results are shown to illustrate the performance of the proposed multiband MIMO antenna system, and that confirms the suitability for LTE and WLAN handset applications.

Modeling of Antenna System for Capsule Endoscopic Complex “Landish”

This article focuses on modeling of different options of antenna system including and in particular an antenna for the capsule endoscope (transmitter antenna) of the capsule endoscopic complex “Landish”. A helical antenna is reviewed for the transmitter, as well as a patch antenna on a curved substrate, and a quarter-wave monopole vibrator and a ceramic antenna. An experiment was conducted in order to compare the gain of the antennas at a fixed position in the space of the transmitting antennas, and the impact of the human body on the features of antennas. Recommendations on the choice of antenna systems in accordance with the simulation results are provided.

In‐the‐ear spiral monopole antenna for hearing instruments

A novel in-the-ear (ITE) antenna solution for hearing instruments that operates at 2.45 GHz is presented. The antenna consists of a quarter wave monopole and a ground plane that are placed in the ear. The simulated path gain | S 21 | is - 86 dB and the measured path gain is - 80 dB. Simulations and measurements show that the antenna covers the entire 2.40-2.48 GHz industrial, scientific and medical (ISM) band. It is the first ever ITE-antenna solution that demonstrates the possibility of establishing an ear-to-ear link by using a standard Bluetooth chip.

SIMULATIONS AND EFFECTS OF NATURAL ENVIRONMENTS ON LOW FREQUENCY ANTENNAS WITH THREE-DIMENSIONAL FDTD METHOD

Three-dimensional Finite-Difference in Time-Domain method is applied to simulate Low Frequency antennas in the presence of natural environments. All antennas are made up of wires set down on a square shaped ground plane and their dimensions depend on the wavelength of the source. Both monopole and inverted L antennas are considered in this paper. The antenna systems are computed in the presence of two examples of natural elements: a large forest and then on the top of a hill. The main aim of this paper is to show the effects of these environments on the properties of the antennas and on the efficiency of the ground wave excitation. The outcome of these investigations shows a power ratio enhancement of several decibels when the two kinds of antenna described in this paper are located on the top of a hill. On the other hand, the effects of a large forest depend on the geometry of the antenna. It doesn't affect the radiation of a quarter-wave monopole antenna, on the contrary losses disrupt radiation when an inverted L antenna is built in the middle of a large forest.

A chip antenna in via-free LTCC with symmetric structure for Bluetooth applications

A chip antenna for Bluetooth applications is proposed. This antenna has three symmetric metallic layers implemented by low-temperature co-fired ceramic (LTCC) technique. Because of the symmetric structure, there is no need to mark the polarity of the antenna. No vias are required in the antenna, which leads to significant simplification of fabrication process. This is achieved by connecting the metallic layers using electrodes at two ends. The antenna behaves as a quarter-wave monopole loaded with inductors and the radiating area is the whole straight metallic strip in the middle layer, so the radiation pattern is omni-directional. The size of the antenna is only 9 × 2 × 1 mm3 at 2.45 GHz. The proposed antenna design is assessed by comparing the related simulated and measured results. The measured results show that the bandwidth of the antenna is 100 MHz (corresponding to 6 dB return loss) and the gain is 1.3 dBi. Measured results validate the novel design of the proposed antenna. In addition, the parametric study and frequency adjustment method are conducted to facilitate the design and optimization processes for engineers.

Dual-Band Printed Fractal Monopole Antenna for LTE Applications

In this letter, a dual-band fractal monopole antenna suitable for Long Term Evolution (LTE) standard is proposed. The antenna geometry is based on a perturbed planar Sierpinski fractal shape, whose geometrical descriptors are determined by means of a particle swarm optimization (PSO). The optimized antenna exhibits a good impedance matching within the LTE bands at 700 and 2600 MHz as well as a 24% size reduction with respect to a standard quarter-wave resonant monopole. The efficiency of the proposed antenna is assessed by means of both simulations and measurements.

A Broadband Monopole Antenna Enabled by an Ultrathin Anisotropic Metamaterial Coating

A new type of compact flexible anisotropic metamaterial (MM) coating is proposed, which greatly enhances the impedance bandwidth of a quarter-wave monopole to over an octave. The MM coating has a high effective permittivity for the tensor component oriented along the direction of the monopole. By properly choosing the radius and tensor parameter of the MM coating, another resonance at a higher frequency can be efficiently excited without affecting the fundamental mode of the monopole. Additionally, the similar current distributions on the monopole at both resonances make stable radiation patterns possible over the entire band. To experimentally verify the concept, an S-band MM coated monopole was designed, fabricated, and characterized, exhibiting a 2.14:1 bandwidth (2.15-4.6 GHz) with a VSWR of less than 2:1. The demonstrated MM coating has a radius of only λ/24 and extremely light weight, which renders it attractive for use in applications such as broadband arrays and portable wireless devices.

Effects of Ground Constituent Parameters on Array Mutual Coupling for DOA Estimation

Effects of ground constituent parameters on the mutual coupling (MC) of monopole antenna array are investigated. This work augments an existing MC compensation technique for ground-based antennas and proposes reduction in mutual coupling for antennas over finite ground as compared to the perfect ground. The work is investigated by finite element method analysis, and numerical results are presented. A factor of 4 decrease in both the real and imaginary parts of the mutual coupling is observed when considering a poor ground versus a perfectly conducting one, for quarter-wave monopoles in receiving mode. A simulated result to show the errors in direction-of-arrival (DOA) estimation with actual realization of the environment is also presented.