Krishnasamy T. Selvan

A MODIFIED THREE-ANTENNA GAIN MEASUREMENT METHOD TO SIMPLIFY UNCERTAINTY ESTIMATION

A modified three-antenna gain measurement method is proposed to significantly simplify, and thereby to reduce the costs of, uncertainty estimation. Unlike the three-antenna method, the new method employs a standard antenna whose gains and uncertainty limits have been established through absolute calibration. The measurements are carried out as in the three-antenna method, with the reference antenna also analysed as presumed unknown. An overall uncertainty figure for the measurement is obtained only from the resulting data in conjunction with the uncertainty on the reference antenna gain values. The proposal is verified by using a rigorous experimental study on the gains of three pyramidal horns in the frequency range 5.8 GHz- 8.2 GHz. First, the gains and error limits of the antennas are estimated by using the three-antenna method. One of the antennas is then used as reference antenna and the modified method employed on the measured data to determine the gains of a test antenna. It emerges that the new method substantially simplifies the secondary calibration and gain measurement of antennas.

A Dual-Band Circular Slot Antenna with an Offset Microstrip-Fed Line for PCS, UMTS, IMT-2000, ISM, Bluetooth, RFID and WLAN Applications

In this paper, a circular slot antenna fed by an ofiset microstrip-fed line is proposed. The antenna exhibits dual-band characteristics. The two operating frequency bands are: 1.83{2.73GHz and 5.36{7.63GHz, which are of impedance bandwidth 39.5% and 34.9% respectively. The bands are suitable for PCS, UMTS, IMT- 2000, ISM, Bluetooth, RFID and WLAN applications. A parametric study has been carried out by varying the location of the feedline to investigate its efiect on the resonant frequency. Impedance, radiation and gain characteristics of the proposed antenna are also presented and discussed.

A Revisiting of Scientific and Philosophical Perspectives on Maxwell's Displacement Current

The displacement-current concept introduced by James Clerk Maxwell is generally acknowledged as one of the most innovative concepts ever introduced in the development of physical science. It was through this that he was led to the discovery of his electromagnetic theory of light. While this concept and its development have received much admiration in the literature from the viewpoints of both scientific content and philosophical methodology, there interestingly has been criticism, as well. This article presents an overview of these perspectives. With the distinctive creative quality of the concept emerging on balance, it is suggested that effective use of it can be made to help students to contemplate innovation and creativity, among other factors.

THE EFFECT OF GROUND PLANE ON THE PERFORMANCE OF A SQUARE LOOP CPW-FED PRINTED ANTENNA

The efiect of shaping the ground plane on the performance of a square loop coplanar waveguide (CPW)-fed printed antenna is reported in this paper. Experimental results are presented on the re∞ection coe-cient and radiation pattern of the investigated antennas. Simulation results are presented on the current distribution, input impedance and gain. It is observed based on the results that shaping the ground plane signiflcantly afiects the re∞ection coe-cients, input impedances and current distributions.

Accurate Design Method for Pyramidal Horns of Any Desired Gain and Aperture Phase Error

An exact solution is presented for the fourth-order polynomial representing the general horn design problem. When the available approximations are used for the gain reduction factors, this leads to closed-form expressions for the aperture, and hence the other, dimensions of the pyramidal horn of any desired gain and aperture phase error.

Engineering Education: Presentation of Maxwell's Equations in Historical Perspective and the Likely Desirable Outcomes

It is suggested that where possible fundamental concepts and theories be presented from a historical perspective in undergraduate engineering education. Apart from being fairer to the contributions of the several researchers whose works often significantly contribute to a later and much-acclaimed theory, such an approach can also be employed to intellectually challenge the young students, and to encourage them to pursue life-long learning. Against this background, a possible method of presenting Maxwells equations in a historical context is presented.

A Performance Comparison of a Ku-Band Conical Horn with an Inserted Cone-Sphere with Horns with an Integrated Dielectric Lens and Metamaterial Loading [Antenna Designer's Notebook]

This article presents a comparative study based on measurements and simulations of a Ku-band conical horn with an inserted metallic cone-sphere with horns having an integrated dielectric lens and meta material loading. The results revealed that the performance of the horn with the cone-sphere was better than that of the metamaterial-loaded horn. The performance of the horn with the cone-sphere was comparable to that of the horn with the dielectric lens. In addition, the horn with the cone-sphere offered advantages of lower weight and cost in comparison to the other horns under consideration.

A metallic cone-sphere inserted conical horn for high-performance applications

A metallic cone-sphere-inserted smooth-wall conical horn operating in the Ku-band that offers improved return loss compared to similar, recent designs is proposed. The other desirable characteristics, namely high gain and compact size, of the earlier designs are retained by the proposed horn. This horn will find potential use in EMC applications, particularly in the measurement of high intensity radiated fields.

The Incorporation of Historical Context into Teaching: Student Perception at The University of Nottingham Malaysia Campus

In order to gain an understanding of what students feel about the incorporation of substantial historical content into engineering teaching, a survey was recently conducted at the University of Nottingham Malaysia Campus. In this article, the results of the survey are presented and their possible meaning is discussed.

Gain Enhancement of Microstrip Patch Antenna by Using Complementary EBG Geometries

This paper considers the gain performance of a square patch antenna when it is enclosed by complementary forms of either circular or square Electromagnetic Bandgap (EBG) cells. This performance is compared against the square patch antenna with EBG structures in their non-complementary forms. It shows that the use of complementary EBG cells results in a comparatively better gain performance. The study includes a consideration of the groundplane size and the number of rows surrounding the patch, as these could affect the gain performance. Initially, antenna configurations with complementary EBG geometries are simulated to observe the gain enhancements. This is followed by experimental measurements to substantiate the simulation outcome. Simulated and measured reflection coefficients (S 11) and co-polarized radiation patterns are in good agreement.