I. M. Ibrahim

A meandered triple-band printed dipole antenna for RFID

In this paper, a meandered triple-band printed dipole antenna is proposed for Radio Frequency Identification (RFID). This meandered tri-band printed dipole antenna is designed to operate at 0.92 GHz, 2.45 GHz and 5.8 GHz with the aid of Computer Simulation Technology (CST) software. In order to achieve triple-band operation, the proposed antenna contains two branch elements, which act as an additional resonator. The designed antenna is fabricated using Taconic RF-35 substrate with a dielectric constant ( εr) of 3.5 and thickness (h) of 0.508 mm. The antennas parameters for triple-band operation are investigated and discussed. Then, this fabricated antenna is integrated with the UHF microchip to become a passive UHF tag. This tag is tested by measuring the reading distance and it is found that the proposed tag can be used for RFID application.

The performance comparison of printed dipole antenna with two different structures of AMC ground plane

The performances of the triple-band meandered dipole antenna backed by two different Artificial Magnetic Conductor (AMC) structures are discussed in this paper. Two kinds of AMC structures are presented namely rectangular-patch with rectangular slot and rectangular-patch with slotted rectangular and I-shaped slot. The AMCs are designed to operate at 0.92GHz and 2.45GHz. The performances of the antenna with and without the dual-band AMC ground plane are investigated in terms of return loss, realized gain and power received. It clearly shows that the printed dipole antenna has a lower gain compared to the printed dipole antenna with high-impedance structure ground plane (GP). Furthermore, the received power of the dipole antenna backed by the 2×2 rectangular-patch with slotted rectangular and I-slot AMC receives a slightly higher power compared to the dipole antenna backed by the 2×2 rectangular-patch with rectangular slot AMC.

Microwave absorbing material using rubber wood sawdust

A flat microwave absorber working at frequency 1.8GHz was developed by impregnation of activated carbon and polyurethane. The activated carbon is prepared from the conversion of rubber wood sawdust through chemical activation process using ZnCl2 solution as the precursor agent. The process involves leaching, heating and washing. The impregnation ratio between ZnCl2 and rubber wood sawdust were at 1∶1, 1.5∶1 and 2∶1. All samples are heated at temperature of 500°C for 60 minutes. It was found that the chemical activation at impregnation ratio of 2∶1 produced high purity activated carbons with 79 percent carbon content. Based on the BET analysis, the surface area of the powder for impregnation ratio 1.5∶1 reported highest value of 1301 m2/g, this formulation is selected for making microwave absorber and it was reported that the reflection loss is recorded 10dB at 1.8 GHz.

A study on effectiveness of FR4 as a dielectric material for radial line slot array antenna for wireless backhaul application

The Radial Line Slot Array (RLSA) Antenna is known for its good characteristics such as low profile, low cost, aesthetically pleasing, ease of installation and simple structure. RLSA antenna normally applied polypropylene as a dielectric material in the middle of the radiating plate and ground plane. This research is focusing on applying FR4 as a dielectric material. The prototype has been simulated, fabricated and measured. The measurement obtained a −15dB of return loss, 11.5dBi of directivity gain and 5% antenna bandwidth.

The effect of the carbon to the S 11 measurement on the pyramidal microwave absorbers

The purpose of this work is to determine the absorption effect by using carbon as absorbing material. It will be used in anechoic chamber in order to avoid reflections that occur on the wall of the chamber. From polystyrene, the absorbers are cut into pyramidal shaped. The pyramidal shaped is chosen because it could meet the specified industrial standards which can work well at wide range of microwave frequency. To verify the performance of the absorber, a measurement is conducted to determine the absorption rate in frequency range 1 to 10 GHz. The absorber also compared to commercial absorber. The results shows carbon is a good material to absorb the microwave energy. The absorber that has been developed is a low cost with reliable performance.

A triple-band dipole antenna with 0.92 GHz AMC-HIS

A triple-band dipole antenna integrated with 0.92 GHz Artificial Magnetic Conductor (AMC) is presented. The AMC structure is called a high-impedance surface (HIS) structure and is useful as a ground plane to the dipole antenna. This structure can be used to prevent the degradation of tag and antenna performance caused by the conductive materials (metal objects) and to increase the antenna gain. This paper begins by investigating the parameters in AMC design such as a patch and gap size. The AMC is characterized by the frequency where the phase of the reflection coefficient is zero degrees and has reflected wave in-phase with the incident wave.

Third order intermodulation distortion effect on the constellation error in RF transmitter of IEEE 802.11a WLAN system

In wireless data communication, an advanced nonlinear distortion analysis is required in order to see its effect to the performance of a Radio Frequency (RF) front-end system. This technical paper therefore, reports the effect of third order intermodulation (IM3) distortion on the constellation error (a key measure of modulation quality) in RF transmitter of IEEE 802.11a wireless local area network (WLAN) system. The selected RF transmitter architecture is based on the off-the-shelf components. Advanced Design System (ADS) software has been used for RF transmitter modeling and simulation. The constellation error simulation is based on the IEEE 802.11a standard. As results, two observations have been obtained. First, it is shown that the IM3 distortion in the RF transmitter for IEEE 802.11a WLAN system must be kept in minimum level in order to get lower constellation error. Second, with the same IM3 distortion level, the constellation error is very sensitive to the IM3 distortion at higher data rate (e.g. 54 Mbps) compared to lower data rate (e.g. 6 Mbps).

Design of portable mini anechoic chamber using low cost composite absorber

This paper presents the absorber in which it is designed and shaped to absorb incident radio frequency (RF) radiation. The absorber is designed using composite material since the significance of the project is to find a potential solution to construct a low cost anechoic chamber. This model of mini anechoic chamber, which is consisting of the new designed absorber, is portable and small in size so that it is more user friendly. The performance of the designed absorber are compared to commercial absorber available. The absorber that has been developed is a low cost absorber with the absorption rate is 16.6% less compared to the commercial absorber.

Dual polarization inset-fed microstrip patch antenna

In this letter, the design of inset fed microstrip antenna is proposed at 45deg and -45deg to achieve the optimum performance of the return loss, antenna gains and polarization loss. A design of the broadband dual-polarized microstrip antennas is proposed by using the simply inset feed technique but slant at desired rotation. In most applications, the requirement of propagation can be met with a single patch structure. However, in some cases, sharp beamwidth was required, as well as maintaining a low profile structure, which arise the development of microstrip patch array antennas. Both design of array antennas in this paper were connected using parallel feed quarter- wave transformer impedance matching technique.

A NOVEL RECONFIGURABLE UWB FILTERING-ANTENNA WITH DUAL SHARP BAND NOTCHES USING DOUBLE SPLIT RING RESONATORS

This study presents a novel technique for designing an ultra-wideband (UWB) filteringantenna with dual sharp band notches. This design is composed of a modified monopole antenna integrated with resonant structures. The monopole antenna is modified using microstrip transition between the feedline and the patch. In addition, block with a triangle-shaped slot is loaded on each side of the ordinary circular patch to produce wide bandwidth with better return loss and higher frequency skirt selectivity. The resonant structures are constructed using two double split ring resonators (DSRR) loaded above the ground plane of the antenna to produce dual band notches and filter out WiMAX (3.3–3.7GHz) and HiperLAN2 (5.4–5.7GHz) frequencies. The band notch position is controlled by varying the length of the DSRR. The reconfigurability feature is achieved by using two PIN diode switches employed in the two DSRR. The measured results show that the proposed filtering-antenna provides wide impedance bandwidth from 2.58 to 15.5GHz with controllable dual sharp band notches for WiMAX and HiperLAN, peak realized gain of 4.96 dB and omnidirectional radiation pattern.