Rozlan Alias

Design of circular patch microstrip ultra wideband antenna with two notch filters

This paper presents a small size UWB patch antenna with two notch filters. U-shaped and J-shaped slots are loaded in the patch of the antenna for WiMAX and WLAN frequency band rejection. The antenna is simulated using the commercially available CST Microwave Studio software. The slots dimensions are systematically adjusted and optimized to achieve the desired band rejection responses. The achieved results demonstrate that the antenna has good performance over the entire working frequency band (3.1 GHz to 10.6 GHz) except WiMAX (3.15-3.7 GHz) and WLAN (5.15-5.85 GHz) notched frequency bands. Moreover, the antenna was fabricated and the simulation results are experimentally validated. The measured results demonstrate a good agreement with the simulations.

Assessment of microstrip patch antenna performance based on dielectric substrate

A performance comparison and analysis between two dielectric substrates with different permittivity for square slot patch antenna is presented in this paper. The reflection coefficient, voltage standing wave ratio (VSWR), bandwidth and gain performances of the proposed antenna at 5.5 GHz have been thoroughly investigated. The antenna is realized using a square patch printed on a dielectric substrate and ground plane. A square slot is loaded on the patch for antenna size reduction. The achieved gain results of FR4 and Rogers at the design frequency are 2.96 dB and 6.4 dB respectively. There is a significant improvement in gain and this indicates that the lower the permittivity the higher the antennas gain. Lastly, to validate the simulated results, scattering parameter measurements have been performed using vector network analyzer and the results show good agreement with simulations.

A modified equivalent conducting surface boundary using hybrid FEM-FDTD technique

The objective of this paper is to introduce the characteristics, relative merits and applications of the hybrid method between the finite-element method (FEM) and the finite difference time domain (FDTD), as applied to computational electromagnetic studies, e.g. antenna scattering modelling problems. A modified equivalent surface boundary using the hybrid FEM-FDTD technique is presented and discussed in terms, of the memory locations and processing time required for updating the equivalent surface currents from FEM to FDTD methods. A reduced equivalent surface size that encloses the radiating part of the antenna is studied and the results are compared with different sizes of the equivalent surface configurations. Several examples are presented and the results were stable and quite reasonable with published data.

Simulation of radiation performance for mobile antennas using a hybrid FEM-FDTD computational technique

The objective of this paper is to study the radiation performance of mobile handsets antenna by using the hybrid method between the Finite-Element Method (FEM) and the Finite Difference Time Domain (FDTD), as applied to computational electromagnetic studies, e.g. antenna scattering modelling problems. An application of modified equivalent surface boundary using the hybrid FEM-FDTD technique [1] is presented and discussed in terms of the memory locations and processing time required for updating the equivalent surface currents from FEM to FDTD methods. A reduced equivalent surface size that encloses the radiating part of the antenna is studied and the results are compared with different sizes of the equivalent surface configurations. Several examples are presented and the results were stable and quite reasonable with published data.

Simulation of Square Ring Microstrip Patch Antenna Performance Based on Effects of Various Dielectric Substrates

This paper presents the impact of dielectric substrates with different relative permittivity ‎used in designing a square ring patch antenna. Choice of suitable substrate material is essential while configuring the square ring microstrip patch antenna, since ‎dielectric constant of a substrate is a basic parameter over regulating return loss, gain, ‎bandwidth, voltage standing wave ratio (VSWR), and effectiveness of radiation ‎pattern. Two fundamental properties of substrate material is considered in this research i.e. dietetic ‎constant and loss tangent. Therefore, increasing the permittivity of substrate ‎material permits compact size of antenna, but return loss, gain and directivity of ‎antenna diminishing with admiration to the increment of dielectric substrate. The ‎proposed geometric antennas have been designed utilising Computer Simulated ‎Technology (CST) Microwave and MATLAB as a tool for the application, the antenna is ‎acknowledged utilising a square ring patch simulated with different dielectric ‎constant and contains radiating patch and ground plane. It has been considered ‎several of dielectric material whose permittivity ranges from 1.96 to 6.15 relying ‎on demand of GSM at desired frequency 1.8 GHz.

Ultra–Wideband Antenna Enhancement with Reconfiguration and Notching Techniques Evaluation

Many researchers have proposed notches and strips for band ‎enhancement or ‎interference reduction of ultra‎–‎wideband (UWB) antenna. Previous studies ‎illustrated the ‎advantage of using slot technologies and strips to change the ‎antenna impedance matching. ‎This study presents a comprehensive overview of ‎the performances of reconfiguration techniques on UWB ‎antennas based on filtering ‎and matching band. Several studies are considered, and ‎the performance of ‎antennas designs that applied slot, strips, parasitic ‎stubs, and spiral loop ‎resonators are compared. Unwanted bands, ‎such as WLAN and WiMAX ‎systems, are interfered with UWB communications. ‎The notches are used for ‎either band rejection or bandwidth enhancement. ‎Moreover, a hexagonal UWB ‎patch antenna with the coplanar waveguide is demonstrated in this paper. The ‎improvement of the UWB antenna bandwidth is realised by incising the patch ‎size. Loading two L-shape strips on the radiation patch achieved band rejection at 5.15 GHz. The simulated parametric study represents different results achieved with ‎different side–‎patch lengths. The best achievements of the proposed design are the ‎UWB bandwidth from 2.8 GHz to 11.5 GHz, and the radiation gain of 4 dB at ‎‎5.8 GHz. Good omnidirectional radiation patterns observe on E-plane by ‎bidirectional patterns provide on H-plane. Finally, the performance and ‎implementing the studied UWB antennas are discussed in details.‎

A COMPACT CPW FED UWB ANTENNA WITH QUAD BAND NOTCH CHARACTERISTICS FOR ISM BAND APPLICATIONS

A quad band-notched compact ultra-wideband (UWB) patch antenna to operate on the industry, scientific, and medical (ISM) bands are presented in this study. A modified hexagonal patch vertex-fed with a coplanar waveguide (CPW) is fabricated on an FR-4 substrate with size of 43× 28× 1.6 mm3 and fractional bandwidth of 133%. The compact antenna operates at a frequency of 2.45 GHz, which is often required for the efficient performance of ISM utilisation. The existing bands share the same bandwidth as that of UWB systems. Therefore, a notched band at 3GHz for worldwide interoperability for microwave access (WiMAX), and a further resonance band at 2.45 GHz for ISM are generated by implementing a meander-line strip on the antenna. Furthermore, the design demonstrates a couple of F-shaped slots and an inverted diamond-shaped slot on the patch. Moreover, a pair of Jshaped slots is loaded on the ground plane. The downlink C-band, wireless local area network (WLAN), and downlink X-band are rejected by the proposed slots, respectively. The current distribution, gain, radiation efficiency, and quad notched parameters of the proposed antenna are studied by using CST software. The demonstrated prototype covers an ISM band at (2.2 GHz–2.6 GHz) with a return loss of −23.45 dB and omnidirectional radiation patterns. A good agreement is observed between measured and the simulated results. This paper has presented a solution for both interference and miniaturised issues.

Antenna Performance Improvement Techniques for Energy Harvesting: A Review Study

The energy harvesting is defined as using energy that is available within the environment to increase the efficiency of any application. Moreover, this method is recognized as a useful way to break down the limitation of battery power for wireless devices. In this paper, several antenna designs of energy harvesting are introduced. The improved results are summarized as a 2×2 patch array antenna realizes improved efficiency by 3.9 times higher than the single patch antenna. The antenna has enhanced the bandwidth of 22.5 MHz after load two slots on the patch. The solar cell antenna is allowing harvesting energy during daylight. A couple of E-patches antennas have increased the bandwidth of 33% and the directivity up to 20 dBi. The received power can be improved by 1.2-1.4 times when using the dual port on pixel antenna. Complementary split ring resonator and substrate integrated waveguide are utilized cavity-backed feeding on a fractal patch antenna to enhance the bandwidth around 5.1%. Moreover, adding a rectifier circuit to an antenna converts the reserved RF-signal to DC power, and then duplicated the input voltage up to sum the total number of rectifier circuit stages. Therefore, the advantages and disadvantages of each antenna depend on the technique which used in design.

A survey of various enhancement techniques for square rings antennas

The square ring shape becomes a famous reconfiguration on antenna design. The researchers have been developed the square ring by different configurations. It has high efficiency and simple calculation method. The performance enhancement for an antenna is the main reason to use this setting. Furthermore, the multi-objectives for the antenna also are considered. In this paper, different studies of square ring shape are discussed. This shape is developed in five different techniques, which are the gain enhancement, dual band antenna, reconfigurable antenna, CSRR, and circularly polarization. Moreover, the validation between these configurations also demonstrates for square ring shapes. In particular, the square ring slot improved the gain by 4.3 dB, provide dual band resonance at 1.4 and 2.6 GHz while circular polarization at 1.54 GHz, and multi-mode antenna. However, square ring strip achieved an excellent band rejection on UWB antenna at 5.5 GHz. The square ring slot length is the most influential factor o...

Strategies for a better performance of RPL under mobility in wireless sensor networks

A Wireless Sensor Network (WSN) is usually stationary, which the network comprises of static nodes. The increase demand for mobility in various applications such as environmental monitoring, medical, home automation, and military, raises the question how IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) would perform under these mobility applications. This paper aims to understand performance of RPL and come out with strategies for a better performance of RPL in mobility scenarios. Because of this, this paper evaluates the performance of the RPL protocol under three different scenarios: sink and sensor nodes are static, static sink and mobile sensor nodes, and sink and sensor nodes are mobile. The network scenarios are implemented in Cooja simulator. A WSN consists of 25 sensor nodes and one sink node is configured in the simulation environment. The simulation is varied over different packet rates and ContikiMAC’s Clear Channel Assessment (CCA) rate. As the performance metric, RPL is evaluated ...