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The fifth-generation (5G) wireless network has received a lot of attention from both academia and industry with many reported efforts. Multiple-input-multiple-output (MIMO) is the most promising wireless access technology for next-generation networks to provide high spectral and energy efficiency. For handheld devices such as smartphones, 2×2 MIMO antennas are currently employed in 4G systems and it is expected to employ a larger number of elements for 5G mobile terminals. Placing multiple antennas in the limited space of a smartphone PCB poses a significant challenge. Therefore, a new design technique using dual-polarized antenna resonators for 8×8 MIMO configuration is proposed for sub 6 GHz 5G applications. The proposed MIMO configuration could improve the channel capacity, diversity function, and multiplexing gain of the smartphone antenna system which makes it suitable for 5G applications. Different types of new and compact diversity MIMO antennas with Patch, Slot, and Planar inverted F antenna (PIFA) resonators are studied for different candidate bands of sub 6 GHz spectrum such as 2.6, 3.6, and 5.8 GHz. Unlike the reported MIMO antennas, the proposed designs provide full radiation coverage and polarization diversity with sufficient gain and efficiency values supporting different sides of the mainboard. Apart from the sub 6 GHz frequencies, 5G devices are also expected to support the higher bands at the centimeter/millimeter-wave spectrums. Compact antennas can be employed at different portions of a smartphone board to form linear phased arrays. Here, we propose new linear phased arrays with compact elements such as Dipole and Quasi Yagi resonators for 5G smartphones. Compared with the recently reported designs, the proposed phased arrays exhibit satisfactory features such as compact size, wide beam steering, broad bandwidth, end-fire radiation, high gain, and efficiency characteristics. The proposed 5G antennas can provide single-band, multi-band, and broad-band characteristics with reduced mutual coupling function. The fundamental characteristics of the 5G antennas are examined using both simulations and measurements and good agreement is observed. Furthermore, due to compact size and better placement of elements, quite good characteristics are observed in the presence of the user and the smartphone components. These advantages make the proposed antennas highly suitable for use in 5G smartphone applications. / European Union Horizon 2020 Research and Innovation Programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424

The fifth generation (5G) has developed a lot of interest, and there have been many reported initiatives in both industry and academics. Multiple-input-multiple-output (MIMO) is the most promising wireless access technique for next-generation networks in terms of spectral and energy efficiency (MIMO). In 4G systems, 2-Element MIMO antennas are already used, while 5G mobile terminals for smartphone hand-held devices are projected to use a bigger number of elements. The placement of many antennas in the restricted space of a smartphone PCB is one of the most critical challenges. As a result, for sub-6 GHz 5G applications, a new design technique based on dual-polarised antenna resonators for 6-Element, 8-Element MIMO configuration is proposed. The proposed MIMO design could improve the smartphone antenna system's chan-nel capacity, diversity function, and multiplexing gain, making it appropriate for 5G applica-tions. For distinct prospective bands of the sub-6 GHz spectrum, such as 2.6, 3.6, and 5.8 GHz, different types of novel and compact diversity MIMO antennas using Patch, Slot, and Planar inverted F antenna (PIFA) resonators are examined. Unlike previously reported MIMO antennas, the proposed designs provide full radiation coverage and polarisation diversity, as well as adequate gain and efficiency values to support several mainboard sides. Apart from sub-6 GHz frequencies, 5G devices are projected to support the centimetre/milli-metre wave spectrum's higher bands. To create linear phased arrays, small antennas can be placed at various locations on a smartphone board. For 5G smartphones, we propose novel linear phased arrays with tiny parts like Dipole and Quasi-Yagi resonators. In comparison to previously published designs, the suggested phased arrays have desirable qualities such as compact size, wide beam-steering, broad bandwidth, end-fire radiation, high gain, and efficiency. With a reduced mutual coupling function, the suggested 5G antennas can provide single-band, multi-band, and broad-band characteristics. Both models and measurements are used to an-alyse the fundamental features of 5G antennas, and good agreement is found. Furthermore, in the presence of the user and the smartphone components, good features are seen due to the small size and superior arrangement of elements. Because of these benefits, the sug-gested antennas are well-suited for usage in 5G smartphone applications.

The recent growth in the ambit of modern wireless communication and in particular WLAN (Wireless Local Area Network) systems has created a niche for novel designs that have the capacity to send and/or receive arbitrary orthogonal polarizations. The designs should also be able to support dual-band functionality, while maintaining a compact structure. The first aim of this dissertation was thus to develop a dual-band single radiating element that can cover the 2.4 GHz (2.4 – 2.484 GHz) band and the 5.2 GHz (5.15 – 5.85 GHz) band for the IEEE 802.11b and IEEE 802.11a WLAN standards respectively. Dual-frequency elements such as stacked-, notched- and dichroic patches have been considered, but due to the size and the high cross-polarization levels associated with these designs, the design process was propelled towards various dipole and monopole configurations. The attributes of various designs were compared, where the double Rhombus antenna pregnant with dual-band and dual-polarization potential was used as basis in the development of the DBDP (Dual-Band Dual-Polarized) antenna design. The single-element design exhibited wide bandwidths, good end-fire radiation patterns and relatively high gain over the 2.4/5.2 GHz bands. A two-element configuration was also designed and tested, to firstly increase the gain of the configuration and secondly to facilitate the transformation of the dipole design into a dual-polarized configuration. The second aim of this dissertation was to develop a dual-polarized array, while making use of only two ports, each pertaining to a specific polarization and to implement the design on a single-dielectric-layer substrate. Most dual-polarized structures such as circular, square and annular microstrip antenna designs only support one band, where multi-dielectric-layer structures are the norm. The disadvantages associated with multi-layered designs, such as fabrication difficulties, high costs, high back lobes and the size of the arrays, further supported the notion of developing an alternative configuration. The second contribution was thus the orthogonal interleaving of the two-element array configurations, to address the paucity of single-dielectric-layer dual-band dual-polarized designs that can be implemented with only two ports. This design was first developed and simulated with the aid of the commercial software package CST Microwave Studio® and the results were later corroborated with the measured data obtained from the Compact Antenna Range at the University of Pretoria. AFRIKAANS : Die onlangse groei in die area van moderne draadlose kommunikasie en met spesifieke verwysing na DLAN (Draadlose Lokale Area Netwerk) stelsels, het ‘n nis vir nuwe ontwerpe geskep. Daar word van hierdie nuwe ontwerpe die kapasiteit verlang om verskeie ortogonale polarisasies te stuur en/of te ontvang in samewerking met dubbel-band eienskappe, terwyl ‘n kompakte struktuur nogsteeds aandag moet geniet. Die eerste doel met hierdie verhandeling was dus die ontwikkeling van ‘n dubbel-band enkel stralingselement wat instaat is om die 2.4 GHz (2.4 – 2.484 GHz) band en die 5.2 GHz (5.15 – 5.85 GHz) band wat as die IEEE 802.11b en die IEEE 802.11a DLAN standaarde respektiewelik bekend staan, te bedek. Dubbel-frekwensie elemente soos onder andere die gepakte-, merkkepie- en dichromatiese strook antenne was as moontlike oplossings ondersoek, maar die grootte en hoë kruispolarisasie wat gewoonlik met hierdie ontwerpe gepaard gaan, het die ontwerpsproses in die rigting van verskeie dipool en monopool konfigurasies gestoot. Die aantreklike eienskappe van die verskeie ontwerpe was met mekaar vergelyk, waar die dubbel Rhombus antenna, verwagtend met dubbel-band dubbel-polarisasie potensiaal, as basis vir die ontwikkeling van die DBDP (Dubbel-Band Dubbel-Polarisasie) antenna ontwerp gebruik is. Die enkelelementontwerp het wye bandwydtes, goeie direktiewe stralingspatrone en relatiewe hoë wins oor die 2.4/5.2 GHz bande geopenbaar. Die twee-element konfigurasies was ook ontwerp en getoets om eerstens die wins van die konfigurasie te verhoog en tweedens om die transformasie na ‘n dubbel-gepolariseerde konfigurasie te fassiliteer. Die tweede doel van hierdie verhandeling was om ‘n dubbel-gepolariseerde elementopstelling met net twee poorte te ontwikkel, waar elkeen verantwoordelik is vir ‘n spesifieke polarisasie, en te implementeer op ‘n enkel-diëlektriese-laag substraat. Die meeste dubble-polarisasiestrukture, soos onder andere die sirkulêre-, vierkantige- en ringvormige antenne ontwerpe, kan net een frekwensieband onderhou en word gewoonlik met behulp van meervoudige-diëlektriese-laagstrukture geimplementeer. Die negatiewe eienskappe soos onder andere die vervaardigingsmoeilikhede, hoë kostes, hoë teruglobbe en die grootte van die meervoudige-elementopstellings wat aan hierdie meervoudige-diëlektriese-laagontwerpe behoort, het verder die denkbeeld van ‘n alternatiewe konfigurasie bekragtig. Die tweede hoofbydrae was dus die ortogonale insleuteling van die twee-element meervoudige-elementopstelling konfigurasies om die geringheid van enkel-diëlektriese-laag dubbel-band dubbel-polarisasie ontwerpe, wat net met twee poorte geïmplementeer kan word, te adresseer. Hierdie ontwerp was eers met behulp van die kommersiële sagtewarepakket CST Microwave Studio® ontwikkel en gesimuleer, waarna die resultate bevestig was deur meetings by die Kompakte Antenna Meetbaan van die Universiteit van Pretoria. / Dissertation (MEng)--University of Pretoria, 2011. / Electrical, Electronic and Computer Engineering / unrestricted