The field of microwave and antenna engineering has been an area of specialization in the Department for more that two decades. In 1986 the Electromagnetism Group under the leadership of Prof. J.A.G. Malherbe was awarded the first Centre of Excellence by the then Foundation for Research Development. In 1990 the Electromagnetism Group received a major stimulation with the opening of the Compact Antenna Test Range for antenna and radar cross section measurements. The facility was significantly upgraded during 2010. This facility, unique as a University-owned research laboratory in the Southern Hemisphere, enables the characterization of antennas in the frequency range from 0.75 to 40GHz.
Since 1986, a total of 33 Masters and 17 Doctoral candidates have graduated at the University in fields related to the work of the group. In the same period more than 160 articles were published in accredited research journals by academic staff and students of the Electromagnetism Group, and more than 95 presentations made at local and overseas conferences. One textbook was published in 1990 - Introduction to the Uniform Geometrical Theory of Diffraction by J.A.G. Malherbe, C.W.I. Pistorius and D.A. McNamara, and two chapters in textbooks were published in 2005 and 2010 respectively, on Lens Antennas by J.A.G. Malherbe, and on the Design of Non-Uniformly Excited Linear Slot Arrays Fed by Coplanar Waveguide, by J.P. Jacobs, J. Joubert and J.W. Odendaal.
The Electromagnetism Group has a long standing specialization in a wide variety of microwave components and antennas. The Group also has research experience in computational methods and antenna measurement techniques. Current research activities of the Group include the following:
The design and analysis of slot and planar antenna elements and arraying of such elements for a wide variety of applications.
The use of metamaterials in single antenna elements and antenna arrays - with the aim to enhance the radiation properties of such antennas.
Development of waveguide horn antennas and TEM horns of extreme bandwidth, suitable for impulse radar applications as well as wideband signal detection.
Development of improved wideband double- and quad-ridged horn antennas.
Design and analysis of passive microwave components such as filters, impedance matching networks, coax-to-waveguide transitions, etc.
Improvement of antenna measurement techniques, eg. improved gain accuracy, calibration of UWB antennas using complex transfer functions.
[1] D.M. de Haaij, J. Joubert and J.W. Odendaal, “Wideband dual-frequency stacked microstrip patch antenna” , Microwave and Optical Technology Letters, vol. 31, no. 4, pp. 289-292, 20 Nov. 2001.
[2] M. da Silveira, J.W. Odendaal and J. Joubert, “Same cell co-channel interference reduction using multiple spatially distributed adaptive array systems”, Signal Processing, vol. 81, pp. 2059-2068, 2001.
[3] J.P. Jacobs, “Refinements to the ergonomic model for keyboard fingering of Parncutt, Sloboda, Clarke, Raekallio and Desian,” Music Perception, vol. 18, no. 4, pp. 505-511, 2001.
[4] J.P. Jacobs, J. Joubert, and J.W. Odendaal, “Radiation efficiency and impedance bandwidth of conductor-backed CPW-fed slot dipole antenna with two-layered dielectric substrate,” Microwave Optical and Technology Letters, vol. 34, no. 2, pp. 138-141, 2002.
[5] P. Niemand, J. Joubert and J.W. Odendaal, “Null-forming synthesis for cylindrical patch arrays”, Microwave and Optical Technology Letters, vol. 32, No 6, pp. 442-446, March 2002.
[6] J.P. Jacobs, J. Joubert and J.W. Odendaal, “Radiation efficiency and impedance bandwidth of conductor-backed CPW-fed slot dipole antenna with two-layered dielectric substrate”, Microwave and Optical Technology Letters, vol. 34, no. 2, pp. 138-141, 20 July 2002.
[7] D.M. de Haaij, J. Joubert and J.W. Odendaal, “Diplexing feed network for wideband dual-frequency stacked microstrip patch antenna ”, Microwave and Optical Technology Letters, vol. 36, no. 2, pp. 100-102, 20 Jan. 2003.
[8] J.W. Odendaal and P. Niemand, “Statistical properties of radar backscatter data for imaging applications”, IEEE Trans. on Antennas and Propagation, vol. 51, No 3, pp. 670-672, March 2003.
[9] G. Mayhew-Ridgers, J.W. Odendaal and J. Joubert, “Single-layer capacitive feed for wideband probe-fed microstrip antenna elements”, IEEE Trans. Antennas and Propagation, vol. 51, no. 6, pp. 1405-1407, June 2003.
[10] D.M. de Haaij, J. Joubert and J.W. Odendaal, “Increasing the bandwidth of a microstrip patch antenna with a single resonant circuit”, Transactions of the SAIEE, vol. 94, No 2, pp. 25-27, July 2003.
[11] P. Niemand, J. Joubert and J.W. Odendaal, “Practical considerations for interference suppression cylindrical arrays”, Transactions of the SAIEE, vol. 94, no. 2, pp. 37-39, July 2003.
[12] J.P. Jacobs, J. Joubert and J.W. Odendaal, ”Radiation efficiency and impedance bandwidth of conductor-backed CPW-fed broadside twin slot antennas on two-layer dielectric substrate”, IEE Proceedings-Microwaves, Antennas and Propagation, vol. 150, No 4, pp. 185-190, Aug. 2003.
[13] J. Joubert, “Spiral microstrip radiators for narrow-stopband filters”, IEE Proc. Microwaves, Antennas and Propagation, vol. 150, no. 6, pp. 493-497, Dec. 2003.
[14] A.J. Bubendorfer, J. Joubert, T. Kemmitt, L.J. Campbell and N.J. Long, “High temperature superconductor films and devices for the microwave communication industry”, Current Applied Physics, vol. 4, Issues 2 – 4, pp. 284-287, April 2004.
[15] G. Mayhew-Ridgers, J.W. Odendaal and J. Joubert, ”Entire-domain versus subdomain attachment modes for the spectral-domain moment-method analysis of probe-fed microstrip patch antennas”, IEEE Transactions on Antennas and Propagation, vol. 52, No 6, pp. 1616-1620, June 2004.
[16] J.W. Odendaal, ”Predicting the directivity of standard gain pyramidal horn antennas”, IEEE Antennas and Propagation Magazine, Vo .46, No 4, pp. 93-98, Aug. 2004.
[17] J.A.G. Malherbe, “Nonradiative dielectric waveguide with a perforated dielectric strip”, Electronics Letters, vol. 41, no. 4, pp. 194-196, 17 Feb. 2005.
[18] J. Joubert and J.W Odendaal, “Wideband quarter-wave patch antenna with a single-layer capacitive feed on a finite ground plane”, Microwave and Optical Technology Letters, vol. 45, no. 3, pp. 225-227, 5 May 2005.
[19] J.A.G. Malherbe, “Integrated dielectric wedge-lens antenna in a nonradiative mode”, Microwave and Optical Technology Letters, vol. 45, no. 4, pp. 361-363, June 5, 2005.
[20] G. Mayhew-Ridgers, J.W. Odendaal and J. Joubert, “Efficient full-wave modelling of patch antenna arrays with new single-layer capacitive feed probes”, IEEE Trans. Antennas and Propagation, vol. 53, no. 10, pp. 3219-3228, Oct. 2005.
[21] J.P. Jacobs, J. Joubert and J.W. Odendaal, “Effect of back plane distance on mutual coupling between CPW-fed slots on conductor-backed two-layer substrates”, Microwave and Optical Technology Letters, vol. 47, no. 5, pp. 407-409, 5 Dec. 2005.
[22] J.W. Odendaal, J. Joubert and M.J. Prinsloo, “Extended edge wave diffraction model for near-field directivity calculations of horn antennas”, IEEE Trans. Instrumentation and Measurement, vol. 54, no. 6, pp. 2469-2473, Dec. 2005.
[23] J. Joubert and J.W. Odendaal, “Analysis and design of wide band reflector gratings in rectangular waveguide”, IEEE Transactions on Plasma Science, vol. 34, no. 3, pp. 659-665, June 2006.
[24] J.A.G. Malherbe and J. Joubert, “Simplified Analytical Solution of Current and Radiation Pattern for Thin Dipoles”, Microwave and Optical Technology Letters, vol. 48, no. 8, pp. 1483-1485, Aug. 2006.
[25] G. Mayhew-Ridgers, J.W. Odendaal and J. Joubert, “Considerations for the efficient spectral evaluation of reaction integrals associated with separated domains”, IEE Proceedings Microwaves, Antennas and Propagation, vol. 153, no. 5, pp. 469-474, Oct. 2006.
[26] M. da Silveira, J.W. Odendaal and J. Joubert, “The Range Increase of Adaptive vs. Phased Arrays in Mobile Systems in the Presence of Interference”, South African Journal of Science, 102, pp. 609-612, Nov./Des. 2006.
[27] A.J. Palmer and D.C. Baker, “A novel semi empirical model for the effective earth radius factor”, IEEE Transactions on Broadcasting, vol. 52, no. 4, pp. 557-565, Dec. 2006.
[28] J.W. Odendaal, L. Botha and J. Joubert, “A full scale static RCS measurement facility”, South African Journal of Science, vol. 103, pp. 196-199, May 2007.
[29] J.A.G. Malherbe and N.S. Barnes, “TEM horn antenna with an elliptic profile”, Microwave and Optical Technology Letters, vol. 49, no. 7, pp. 1548-1551, Jul. 2007.
[30] J.A.G. Malherbe and P.M. Malekela, “Dielectric wedge antenna with stepped phase correction in a nonradiative mode”, Microwave and Optical Technology Letters, vol. 49, no. 8, pp. 2030-2032, Aug. 2007.
[31] C. Dohmen, J.W. Odendaal, and J. Joubert, “Synthesis of conformal arrays with optimized polarization” IEEE Transactions on Antennas and propagation, vol. 55, no. 10, pp. 2922-2925, Oct. 2007.
[32] J.P. Jacobs, “Self and mutual admittance of CPW-fed slots on conductor-backed two-layer substrate”, Microwave and Optical Technology Letters, vol. 49, no. 11, pp. 2798-2802, Nov. 2007.
[33] J. Joubert and J.W. Odendaal, “Characterization of a first-resonance CPW-fed slot as an array element”, Microwave and Optical Technology Letters, vol. 50, no. 6, pp. 1523-1527, June 2008.
[34] J. Joubert and J.W. Odendaal, “A 2×2 etched slot array with a corporate slotline feed network”, Electronic letters, vol. 44, no. 14, pp. 833-834, July 2008.
[35] J. Joubert and J.W. Odendaal, “An impedance matching design approach for a dual-band coplanar-waveguide-fed slot antenna”, Microwave and Optical Technology Letters, vol. 50, no. 8, pp. 2031-2034, Aug. 2008.
[36] J.A.G. Malherbe, “Extreme performance TEM horn”, Microwave and Optical Technology Letters, vol. 50, no. 8, pp. 2121-2125, Aug. 2008.
[37] J.B. du Toit, J.W. Odendaal, and J. Joubert, “Characterization and phase compensation of a coplanar waveguide to coplanar strip line balun”, Journal of Electromagnetic Waves and Applications, vol. 22, no. 17/18, pp. 2463-2474, 2008.
[38] J.P. Jacobs, J. Joubert and J.W. Odendaal, “Extended reciprocity-based computation of mutual admittance between CPW-fed slots on conductor-backed two-layer substrates”, Microwave and Optical Technology Letters, vol. 51, no. 1, pp. 91-94, Jan. 2009.
[39] J.A.G. Malherbe, “Erratum: Extreme performance TEM horn”, Microwave and Optical Technology Letters, vol. 51, no. 2, p. 583, Feb. 2009.
[40] J.A.G. Malherbe, “Frequency-independent performance of elliptic profile TEM horns”, Microwave and Optical Technology Letters, vol. 51, no. 3, pp. 607-612, March 2009.
[41] J.P. Jacobs and J. Joubert, “Fast and efficient calculation of mutual admittance between CPW-fed slots on electrically thin substrates”, International Journal of RF and Microwave Computer-Aided Engineering, vol. 19, no. 2, pp. 277-284, March 2009.
[42] J.P. Jacobs and J. Joubert, “Design of a linear non-uniform CPW-fed slot array with reduced sidelobe levels”, Microwave and Optical Technology Letters, vol. 51, no. 9, pp. 2175-2178, Sept. 2009.
[43] J.M. Steyn, J.W. Odendaal and J. Joubert, ”Double dipole antenna for dual-band WLAN applications”, Microwave and Optical Technology Letters, vol. 51, no. 9, pp. 2034-2038, Sept. 2009.
[44] W.P. du Plessis, J.W. Odendaal and J. Joubert, “Extended analysis of retrodirective cross- eye jamming”, IEEE Trans. Antennas and Propagation, vol. 57, no. 9, pp. 2803-2806, Sept. 2009.
[45] E. S. Sithole and J. A. G. Malherbe, “Log periodic bandstop filter”, Microwave and Optical Technology Letters, vol. 51, no. 10, pp 2418-2420, Oct. 2009.
[46] E. Botha, J. Joubert and D.A. McNamara, “Alternative formulation and applications aspects of the Generalized Projection Method for array antenna synthesis”, International Journal of RF and Microwave Computer-Aided Engineering, vol. 19, no. 6, pp. 657-668, Nov. 2009.
[47] G. Mayhew-Ridgers, J.W. Odendaal and J. Joubert, “Improved diffraction model and numerical validation for horn antenna gain calculations”, accepted for publication in International Journal of RF and Microwave Computer-Aided Engineering, vol. 19, no. 6, pp. 701-711, Nov. 2009.
[48] J.M. Steyn, J.W. Odendaal and J. Joubert, “Dual-band dual-polarized array for WLAN applications”, Progress in Electromagnetics Research C, vol. 10, pp. 151-161, 2009.
[49] B. Jacobs, J.W. Odendaal and J. Joubert, “The effect of manufacturing and assembling tolerances on the performance of double-ridged horn antennas”, Journal of Electromagnetic Waves and Applications, vol. 24, no. 10, pp. 1279-1290, 2010.
[50] J. Joubert, J.W. Odendaal and J. Prinsloo, “High-gain dual-polarised planar slot array for WLAN applications”, Electronics Letters, vol. 46, no. 15, pp. 1048-1050, July 2010.
[51] W.P. Du Plessis, J.W. Odendaal and J. Joubert, “Experimental Simulation of Retrodirective Cross-Eye Jamming”, IEEE Transactions on Aerospace and Electronic Systems, Vol. 47, No. 1, pp. 734-739, Jan. 2011.
[52] W.P. Du Plessis, J.W. Odendaal and J. Joubert, “Tolerance Analysis of Cross-Eye Jamming Systems”, IEEE Transactions on Aerospace and Electronic Systems, Vol. 47, No. 1, pp. 740-745, Jan. 2011.
[53] O.B. Jacobs, J.W. Odendaal and J. Joubert, “Analysis and design of a wide band omnidirectional antenna’, Microwave and Optical Technology Letters, Vol. 53, No. 6, pp. 1352-1356, June 2011.
[54] J.A.G. Malherbe, “Pseudo-elliptic bandpass filter with subharmonic stubs”, Electronics Letters, vol. 47, no. 3, pp. 196-198, 2011.
[55] J.A.G. Malherbe and A. Swiatko, “Modified Chebyshev bandstop filter with transmission zeros at real frequencies”, Microwave and Optical Technology Letters, vol. 53, no 1, pp. 177-180, 2011.
