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A highly directive 3D-printed dual beam waveguide slotted antennas designed at 28 GHz are presented in this work. By having dual-beam directional pattern, the coverage area can be doubled. The performance of dual-beam waveguide slotted antennas is investigated with new metal 3D printing technique. The slots are basically designed at half wavelength dimension and distance with symmetrical and asymmetrical offset to form different phase radiations. The longitudinal slotted arrays are implemented on both side of the waveguide broad walls, thus enabling the dual beams on the antenna. The proposed antennas are simulated using computer simulation technology software and fully metal printed using EOS M280 machine. The simulated performance is validated experimentally using network analyzer measurement. The dimensional tolerance and surface roughness are profiled in this work. A good match better than 10 dB is achieved. The antennas are proposed for three-dimensional beamforming in millimetre wave applications.

CPW monopoles with textile artificial magnetic conductor (AMC) sheet-like waveguide were designed with the goal to improve transmission between antennas. The AMC substrate is made of Fleece fabric while SHIELDIT fabric is used for the conducting parts. A small AMC sheet as well as an AMC waveguide jacket were fabricated. Experiments were carried out in free space and near to human body settings, with different orientations being considered. The S21 transmission between two monopoles is improved up to maximum 29 dB with the presence of AMC surface. For both free space and on-body placements, significant transmission enhancement has been observed for all the tested positions. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:197–200, 2015

A composite right-/left-handed transmission line metamaterial antenna with enhanced bandwidth and efficiency is proposed. The antenna combines zeroth-order resonant (ZOR) and positive-order resonant (POR) modes for the bandwidth enhancement. An asymmetrical coplanar waveguide technique is used to feed the antenna and also to achieve certain degree of compactness. The overall size of the antenna is 0.32λ0 × 0.38λ0 × 0.012λ0 (40 × 48 × 1.52 mm) at 2.4 GHz. Simulation results show that a bandwidth enhancement of 41% is obtained with the radiation efficiencies of 95 and 97% for the ZOR and POR modes, respectively. The measured impedance bandwidth shows that the antenna has potential applications for WLAN (2.39–2.45 GHz) and WiMAX (2.5–2.69 GHz) operations. The simulated and measured antenna performances in terms of return loss and the radiation patterns are presented and compared. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:252–256, 2015

This article proposes a novel circular patch antenna with polarization reconfigurability features. The antenna has a simple structure, which comprises of a radiating circular patch, embedded with two switches (PIN diode) and a pair of equal length slit on the top metal layer. By controlling the biased voltage of the PIN diodes, the polarization of the antenna can be reconfigured between three states; either linear polarization, right-hand or left-hand circular polarization. The details of the simulated and experimental results are presented and discussed. The proposed design has the potential application to improve channel reliability in a wireless communication system, especially in dealing with multipath-rich and limited space environment. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2587–2590, 2014

REFERENCES1. Comite Europeen de Normalisation (CEN), European Standard EN12253, July 2004.2. O. Leonardi, M. Pavone, T. Cadili, G. Sorbello, and T. Isernia, Mon-olithic patch antenna for dedicated short-range communications,Electron Lett 49 (2013), 85–86.3. B.R. Franciscatto, T.P. Vuong, T.T. Trang, and C. Defay, Micro-strip-fed quasi-Yagi antenna array for a different DSRC system, In:International Symposium on Antenna Technology and Applied Elec-tromagnetics, 2012, pp. 1–5.4. T. Varum, J. Matos, P. Pinho, R. Oliveira, and J. Lopes, Microstripantenna array for multiband dedicated short range communicationsystems, Microwave Opt Technol Lett 53 (2011), 2794–2796.5. D. Megnet and H. Mathis, Circular polarized patch antenna for 5.8GHz dedicated short-range communication, In: European MicrowaveConference (EuMC), Rome, Italy, 2009, pp. 638–641.6. M.T. Le, Q.C. Nguyen, T.P. Vuong, and C. Defay, Design of a highgain antenna at 5.8 GHz using a new metamaterials structure, In:Fourth International Conference Communications and Electronics(ICCE), IEEE, 2012, pp. 411–416.7. S. Maddio, A. Cidronali, S. Maurri, and G. Manes, Compact ETSIcompliant DSRC transponder for vehicular communications at 5.8GHz, In: 19th International Conference on Microwave Radar andWireless Communications (MIKON), Vol. 1, 2012, pp. 350–353.8. S. Maddio, A. Cidronali, I. Magrini, and G.Manes, A new designmethod for single-feed circular polarization microstrip antenna withan arbitrary impedance matching condition, IEEE Trans AntennaPropag 59 (2011), 379–389.9. C.A. Balanis, Antenna theory, Wiley, New York, 1997.10. Ansys Electromagnetic, Available at: http://www.ansys.com/.

A new reconfigurable multiband antenna is presented. The antenna operates in triple band and can be switched to operate either in single or dual band. The multifrequency band is achieved by using slots dipole antenna fed by a coplanar waveguide (CPW). Six switches are used and positioned at specific locations in the slots to achieve frequency reconfigurability. The antenna reconfiguration is realized when the dipole arms are coupled or decoupled from the slot edges. Three different sub-band frequencies (2.40, 3.50, and/or 5.20 GHz) are obtained. Measured and simulated results are presented. The proposed antenna may be suitable for future multimode applications such as cognitive radio systems. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:735–740, 2014

A new modified planar dielectric resonator antenna (DRA) is presented and investigated. The proposed DRA is excited by a microstrip feed that is extended as a probe in the proximity of the DR. On the opposite side to the probe excitation printed narrow strips directly connected to the ground plane edge are used to improve the radiation characteristics of the antenna by keeping a unidirectional broadside radiation. In addition, the short circuit strips introduce a second frequency band. Thus, a dual-band antenna is achieved. The measured bandwidths are about 73% (2.78-5.95 GHz) for the wideband DRA as well as 8% (2.4-2.6 GHz) and 56% (3.3-5.85 GHz) for the dual-band DRA. The minimum and maximum gain enhancements of about 0.6 and 1.2 dB from 3.5 to 6 GHz are obtained. Parametric study and measurement results are presented and discussed. © 2013 Wiley Periodicals, Inc.

This article presents the design, simulation, and fabrication of a new planar left-handed metamaterial (LHM), which consist of a combination of a modified square rectangular split ring resonator and strip wire. Both structures are on the same plane. The structure is simulated and measured with the microstrip antenna operating at frequency 5.8 GHz. The LHM has been analyzed using Nicolson-Ross-Weir approach to obtain the negative permeability and permittivity at 5.8 GHz. The fabrication of the LHM is on FR-4 board substrate. From the simulation and measurement results, the gain of the microstrip antenna with LHM has increased by 4.0 dB. The return loss of the antenna with LHM is improved to 15.7 dB compare without LHM structure.

A frequency reconfigurable antenna using log-periodic technique is reported. A 13 square patches fed by inset feed line technique are connected with a single transmission line by a log-periodic array formation to form a wideband frequency from 3 to 6 GHz. By applying 13 PIN diodes at the transmission line with a quarter wavelength radial stub biasing, three different sub-band frequencies (3–4, 3.7–5, and 4.8–6 GHz) are configured by switching ON and OFF the PIN diodes. The antenna has a directive radiation pattern and gain about 6–8 dB at all sub-bands. Simulated and measured results with antenna design are presented and they show that a good agreement in term of return loss. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1407–1412, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26826

The fractal Koch curve is one of the popular fractals shape. This article discussed the analysis of the fractal Koch dipole antenna (FKDA) using log periodic technique. The effect of flare angle of the antenna has been described to reduce the antenna size. The antenna is operated at ultrahigh frequency (UHF) band frequency between 460 MHz and 4 GHz. The analysis is based on the number of elements, degree of flare angle, current distribution, and radiation pattern of the antennas. The antenna has been designed and simulated using computer simulation technology (CST) and fabricated using FR4 board. The performance of the antennas has been measured, analyzed, and discussed in this article. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2612–2614, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24702