An internal small antenna usually suffers from degradation in performance of impedance bandwidth and radiation patterns. In this thesis, we design and fabricate a broadband interior type planar monopole with an omni-directional radiation pattern over a wide operation band using a slant feeding strip. It has a measured impedance bandwidth about 465MHz with center frequency at 1.66GHz (1427 ¡V 1892MHz) and the maximum cross polarization level about -13dB at 1800MHz, which is GSM1800 band in mobile communications. A modified design is an interior planar monopole with a slant slit. It has a measured impedance bandwidth about 455MHz with center frequency at 1.71GHz (1487 ¡V 1942MHz), including GSM1800 and PCS1900 band, and the maximum cross polarization level about -15dB at 1800MHz. The antennas have the dimensions of 40mm*15mm which occupies a small size on the system board and they are suitable to be mounted within the mobile handset device.

Several novel designs of printed monopole antennas are proposed and experimentally studied. These antennas have the advantages of low profile, light weight and easy construction and can be printed on dielectric substrates and integrated with associated circuitry on the same substrates, which not only reduces the manufacturing cost but also decreases the required size of the complete system. This dissertation mainly consists of four sections and several novel designs are introduced in each section. First, a novel dual-band antenna with two stacked inverted-F strips and a CPW-fed folded inverted-F strip antenna are proposed. Second, a novel printed dual-band double-T monopole antenna, comprising two stacked T-shaped monopoles, is discussed. Third, three diversity antenna designs obtained by protruding a ground plane with optimal dimensions between two printed monopoles for WLAN communication applications in the 2.4 GHz and 5.2 GHz bands are presented. Good dual-polarized radiation with an enhanced port decoupling (isolation less than ¡V27 dB) for the two feeding ports is obtained. Finally, a novel printed ultra-wideband diversity monopole antenna is shown. The operating bandwidth of the ultra-wideband antenna reaches about 5.4 GHz, covering the WLAN bands at 2.4, 5.2 and 5.8 GHz, and the antenna can provide spatial diversity to combat the multipath fading problem.

Yes / This study proposes a compact design of frequency-reconfigurable antenna array for fifth generation (5G) cellular networks. Eight compact discrete- fed slot antennas are placed on the top portion of a mobile phone printedcircuit- board (PCB) to form a beam-steerable array. The frequency response of the antenna can be reconfigured to operate at either 28 GHz or 38 GHz, two of the candidate frequency bands for millimeter-wave (MM-Wave) 5G communications. The reconfigurability function of the proposed design can be achieved by implementing and biasing a pair of diodes across each T-shaped slot antenna element. Rogers RT 5880 with thickness of 0.508 mm and properties of ε = 2.2 and δ = 0.0009 has been used as the antenna substrate. The antenna element is very compact in size with a good end-fire radiation pattern in the frequency bands of interest. The proposed beam-steerable array provides very good 3D coverage. The simulation results show that the proposed design provides some good characteristics fitting the need of the 5G cellular communications. / Innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424, UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1

Recent technologies enable wireless communication devices to become physically smaller in size. Antenna size is obviously a major factor that limits miniaturization. In the past few years, new designs of low-profile antennas for handheld wireless devices have been developed. The major drawback of many low-profile antenna designs is their narrow impedance bandwidth. Furthermore, the market trend of personal wireless devices is moving toward a universal system that can be used anywhere and rapid expansion of the wireless communication industry has created a need for connectivity among various wireless devices using short-range wireless links in the Bluetooth operating band to get rid of the cable connections. This requires therefore multiple frequency band operation. In summary, physically small size, wide bandwidth, and high efficiency are the desired characteristics of antennas in mobile systems. This dissertation presents a comprehensive analysis of a new wide-bandwidth compact antenna, called WC J-pole antenna, covering 50 % impedance fractional bandwidth. A set of guidelines is also provided for a bandwidth-optimized design at any frequency. A few design variations of the proposed antenna are also presented for existing commercial wireless applications. Efficiency is perhaps the most important characteristic of small antennas for mobile systems. An extension of the Wheeler cap method to moderate-length and wideband antennas is developed to measure quickly efficiency. The dissertation also provides a review of human operator interaction with handset antennas. Since the proposed antenna is intended to be used in the proximity of human body and in a casing, coupling effects of human body and casing on the antenna characteristics and radio frequency (RF) energy absorption into the human body are investigated. / Ph. D.

This thesis focuses on mobile phones antenna design with brief description about the historical development, basic parameters and the types of antennas which are used in mobile phones. Mobile phones antenna design section consists of two proposed PIFA antennas. The first design concerns a single band antenna with resonant frequency at GPS frequency (1.575GHz). The first model is designed with main consideration that is to have the lower possible PIFA single band dimensions with reasonable return loss (S11) and the efficiencies. Second design concerns in a wideband PIFA antenna which cover the range from 1800MHz to 2600MHz. This range covers certain important bands: GSM (1800MHz & 1900MHz), UMTS (2100MHz), Bluetooth & Wi-Fi (2.4GHz) and LTE system (2.3GHz, 2.5GHz, and 2.6GHz). The wideband PIFA design is achieved by using slotted ground plane technique. The simulations for both models are performed in COMSOL Multiphysics.  The last two parts of the thesis present the problems of mobile phones antenna. Starting with Specific absorption rate (SAR) problem, efficiency of Mobile phones antenna, and hand-held environment.

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / This paper will discuss the design of a new antenna element for use on vehicles requiring a thin conformal antenna such as on missiles or targets. The new element employs a partial shorted edge, which reduces the size of the element compared to a traditional microwave patch, while maintaining the impedance bandwidth.

International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada / TIW Systems has developed a modern, compact, modular, antenna controller (ACU) for telemetry, tracking, and communications antennas. The controller combines the functions of an antenna control unit, a position conversion/display chassis, and a polarization control unit. By using plug-in cards, a tracking receiver, autophasing control unit, tracking synthesizer, and other functions can be added. Depending on the requirements, the tracking receiver can be a simple wide-band steptrack receiver, or can be a full function phase-locked-loop (PLL) autotrack receiver. In the past, all this capability would have taken a large portion of an entire equipment rack. The unit uses modern microprocessor technology for digitally controlling the position and rate of the antenna. Advanced tracking modes and remote control can be added by connecting an external computer (PTIC) to one of the ACU’s serial ports. The PTIC also provides a user friendly operator interface through the use of high resolution color graphics and easy to understand menus.

<p>The demand of small size electronic systems has been increasing for several decades. The physical size of systems is reduced due to advancements in integrated circuits. With reduction in size of electronic systems, there is also an increasing demand of small and low cost antennas. Patch antennas are one of the most attractive antennas for integrated RF front end systems due to their compatibility with microwave integrated circuits. To fulfil the demand of integrated RF front end systems, a design of microstrip patch antenna with optimum performance at 70GHz is investigated. The procedure could be extended to design other planar antennas that act in a similar way.</p><p>In this work, three different design methods to design patch antennas for applications at 70GHz are investigated that include use of analytical models, numerical optimization, and numerical variation of dimensions. Analytical models provide a basic understanding of the operation of a patch antenna and they also provide approximate dimensions of a patch antenna for a targeted frequency without using numerical simulations. However, as the operating frequencies of RF systems reach mm-wave frequencies, we expect that the accuracy of analytical models become less accurate. For example, the excitation of substrate modes and effect of ground size are not predicted in simple analytical models.</p><p>Due to these expected limitations of the analytical design methods, the accuracy of these models is investigated by numerical electromagnetic field simulations. In this work, CST Microwave Studio Transient Solver is used for that purpose. In order to make sure that the appropriate settings of the solver are applied, the simulation settings such as mesh density, boundary conditions and the port dimensions are investigated. The simulation settings may affect computation time and convergence of the results. Here, in this work, the accuracy of the simulator for a specific design of inset feed rectangular patch antenna is verified. The patch dimensions obtained from analytical calculations are optimized at 70GHz by using the optimizer of the transient solver. The patch dimensions obtained from optimizer are verified by varying the patch dimensions in equidistant steps around the found result of the optimizer.</p><p>In a rectangular microstrip patch antenna design, the use of a width of 1.5 times the length is an approximate rule of thumb [1] for low dielectric constant substrates. It is also investigated how the performance properties of a microstrip patch antenna are affected by varying the width to length ratio of the patch. There are occasions where a different ratio is required because of space limitations, or to change the input impedance. The patch designs having various width to length ratios were optimized with the feed location.</p><p>The analytically calculated dimensions provided good initial values of the rectangular patch antenna for further optimization using more accurate techniques. The design have been optimized at 70GHz for the investigated mesh density, boundary conditions and the port dimensions. The numerical variation of dimensions is found to be most reliable among the investigated design methods but it is more complicated with many parameters.</p>

Inter-site interference distribution acts as a basic limitation on how much performance a network service provider can achieve in an urban network scenario. There are many different ways of controlling this interference levels. One such method is tuning the antenna downtilt depending on the network situation. Antenna downtilt can also be seen as a powerful tool for load balancing in the network. This thesis work involves a study of the impact of the antenna downtilt in an urban environment, involving non-uniform user distribution. A realistic dual ray propagation model is used to model the path gain from the base station to a UE. Such a propagation model is used along with a directional antenna radiation pattern model to calculate the overall path gain from the base station to a UE. Under such modeling, the results of the simulations show that the antenna downtilt plays a crucial role in optimizing the network performance. The results show that the optimal antenna downtilt angle is not very sensitive to the location of the hotspot in the network. The results also show that the antenna downtilt sensitivity is very much dependent on the network scenario. The coupling between the antenna downtilt and the elevation half power beamwidth is also evaluated.

The demand of small size electronic systems has been increasing for several decades. The physical size of systems is reduced due to advancements in integrated circuits. With reduction in size of electronic systems, there is also an increasing demand of small and low cost antennas. Patch antennas are one of the most attractive antennas for integrated RF front end systems due to their compatibility with microwave integrated circuits. To fulfil the demand of integrated RF front end systems, a design of microstrip patch antenna with optimum performance at 70GHz is investigated. The procedure could be extended to design other planar antennas that act in a similar way. In this work, three different design methods to design patch antennas for applications at 70GHz are investigated that include use of analytical models, numerical optimization, and numerical variation of dimensions. Analytical models provide a basic understanding of the operation of a patch antenna and they also provide approximate dimensions of a patch antenna for a targeted frequency without using numerical simulations. However, as the operating frequencies of RF systems reach mm-wave frequencies, we expect that the accuracy of analytical models become less accurate. For example, the excitation of substrate modes and effect of ground size are not predicted in simple analytical models. Due to these expected limitations of the analytical design methods, the accuracy of these models is investigated by numerical electromagnetic field simulations. In this work, CST Microwave Studio Transient Solver is used for that purpose. In order to make sure that the appropriate settings of the solver are applied, the simulation settings such as mesh density, boundary conditions and the port dimensions are investigated. The simulation settings may affect computation time and convergence of the results. Here, in this work, the accuracy of the simulator for a specific design of inset feed rectangular patch antenna is verified. The patch dimensions obtained from analytical calculations are optimized at 70GHz by using the optimizer of the transient solver. The patch dimensions obtained from optimizer are verified by varying the patch dimensions in equidistant steps around the found result of the optimizer. In a rectangular microstrip patch antenna design, the use of a width of 1.5 times the length is an approximate rule of thumb [1] for low dielectric constant substrates. It is also investigated how the performance properties of a microstrip patch antenna are affected by varying the width to length ratio of the patch. There are occasions where a different ratio is required because of space limitations, or to change the input impedance. The patch designs having various width to length ratios were optimized with the feed location. The analytically calculated dimensions provided good initial values of the rectangular patch antenna for further optimization using more accurate techniques. The design have been optimized at 70GHz for the investigated mesh density, boundary conditions and the port dimensions. The numerical variation of dimensions is found to be most reliable among the investigated design methods but it is more complicated with many parameters.