Optical nanoantennas have raised much interest during the past decade for their vast potential in photonics applications. This thesis investigates the response of periodic arrays of nanomonopoles and nanodipoles on a silicon substrate, covered by water, to variations of antenna dimensions. These arrays are illuminated by a plane wave source located inside the silicon substrate. Modal analysis was performed and the mode in the nanoantennas was identified. By characterizing the properties of this mode certain response behaviours of the system were explained. Expressions are offered to predict approximately the resonant length of nanomonopoles and nanodipoles, by accounting for the fringing fields at the antenna ends and the effects of the gap in dipoles. These expressions enable one to predict the resonant length of nanomonopoles within 20% and nanodipoles within 10% error, which significantly facilitates the design of such antennas for specific applications.

In this research, an innovative phased array antenna module is proposed to implement a high-power, high-efficient and compact C-band radio transmitter. The module configuration, which can be integrated into front-end circuits, was designed as planar layers stacked up together to form a metallic cube. The layers were fabricated by using a Computer Numerical Control (CNC) milling machine and screwed together. The antenna parts and the amplifier units were designed at two opposite sides of the cube to spread the dissipated heat produced by the amplifiers and act as a heat sink. Merging the antenna parts with the amplifier circuits offers additional advantages such as decreasing the total power loss, mass, and volume of the transmitter modules by removing the extra power divider and combiner networks and connectors between them as well as reducing the total signal path. To achieve both a maximum possible radiation efficiency and high directivity, the aperture waveguide antenna was selected as the array element. Four antenna elements have been located in a cavity to be excited equally and the cavity is excited through a slot on its underside so a compact subarray is formed. Antenna measurements demonstrated a 15.5 dBi gain and 20 dB return loss at 10 % fractional bandwidth centered around 5.8 GHz and with more than 98% radiation efficiency. The total dimensions of the subarray are approximately 8*12*4 cm3. The outcoming signal from the amplifiers is transferred into the slot exciting the subarray through a microstrip-to-waveguide transition (MWT). A novel and robust MWT structure was designed for the presented application. The MWT was also integrated with a microstrip coupler to monitor the power from the amplifier output. The measured insertion loss of the MWT along with the microstrip coupler was less than 0.25 dB along with more than 20 dB return loss within the same bandwidth of the subarray. The microstrip coupler shows 38 dB of coupling and more than 48 dB of isolation with negligible effects on the amplifier output signal and the insertion/return loss of the MWT. The amplifier subcomponents consist of power combiners/dividers (PCDs), high power amplifiers (HPAs) and bias circuitry. A Monolithic Microwave Integrated Circuit (MMIC) three-stage HPA was designed in a commercially available 0.15 um AlGaN/GaN HEMT technology provided by National Research Council Canada (NRC) and occupies an area of 4.7*3.7 mm2. To stabilize the HPA, a novel inductive degeneration technique was successfully used. To the best of the author’s knowledge, this is the first time this technique has been used to stabilize HPAs. Careful considerations on input/output impedances of all HEMTs were taken into account to prevent parametric oscillations. Other instability sources, i.e. odd-mode, even-mode, and low frequency (bias circuit) oscillations were also prevented by designing the required stabilization circuits. The electromagnetic simulation of the HPA shows 35 W (45.5 dBm) of saturated output power, 26 dB large signal gain and 29% power added efficiency within the same operating bandwidth as the subarray. The output distortion is less than 27 dB, indicating that the HPA is highly linear. The PCD was designed by utilizing a novel, enhanced configuration of a Gysel structure implemented on Rogers RT-Duroid5880. The insertion loss of the Gysel is less than 0.2 dB while return loss and isolation are greater than 20 dB over the entire bandwidth. The same subarray area (8*12 cm2) has been used for the amplifier circuits and up to eight HPAs can be included in each module. All the above parts of the transmitter module were fabricated and measured, except the MMIC-HPA.

The aim of this work is to design and realise millimetre-wave low profile on-chip antennas for 60 GHz short-range wireless communication systems. For this application, it is highly desirable that the antenna can be compatible with standard silicon complementary metal oxide semiconductor (Si CMOS) technology for high level integration and mass production a low cost. Firstly, millimetre-wave antennas on normal dielectric substrates and cavities were studied in detail in order to better understand how the antenna parameters could have effects on their performance at millimetre-wave spectrum. On-chip 60 GHz antennas based on Si CMOS technology were then proposed, designed, fabricated and characterised. A millimetre-wave U-shaped slot antenna with wide bandwidth was first investigated, simulated and designed. The simulation results reveal that this antenna can operate at millimetre-wave frequencies with 1 GHz bandwidth at 73.5 GHz and 76.5 GHz, respectively. A 60 GHz folded dipole antenna was also studied and designed. A metal cavity was added on the back of a folded dipole antenna to act as reflector. Simulated results show that a folded dipole antenna with a metal cavity can achieve a radiation efficiency of 97.9% at its resonant frequency. Compared to the gain obtained for the folded dipole antenna without a cavity, the antenna gain with metal cavity can be enhanced by 3.58 dB. The main challenges of making high gain and high efficiency Si CMOS on-chip antennas at millimetre-wave spectrum come from two sources; the thin silicon dioxide (SiO2) layer (maximum 10 micrometre) and silicon substrate loss (10 ohmscm). The thin SiO2 layer prevents the use of an elevated ground plane, which could significantly reduce the silicon substrate loss, due to the imaging current effect. Si CMOS substrates normally have resistivity of 10 ohmscm, which is very lossy at millimetre-wave spectrum. To tackle these challenges, metamaterial structures, named artificial magnetic conductor (AMC) structures, were studied and utilised for low profile Si CMOS on-chip antenna design and realisation. AMC forms high impedance on its surface, reflecting the incident wave without phase reversal so as to enhance the radiation efficiency. The AMC folded dipole antenna was designed with a mushroom-shaped structured metamaterial cavity. Simulation results show that the gain increased 1.5 dB in the antenna with AMC structure, while the distance to the metamaterial surface was reduced by 90% compared to that of the pure metal cavity. Additionally, two low profile Si CMOS on-chip antennas with novel planar AMC structures were designed, fabricated and characterised. They were manufactured by 0.13 μm Si CMOS technology from Chartered foundry and 0.18 μm Si CMOS technology from TSMC, respectively. The techniques proposed in these two antennas provide valuable alternatives to the existing approaches. The measurement results show that bandwidth of the on-chip antenna with a micro-patterned artificial lattice is approximately 10 GHz. The one with a dog-bone shape and uniplanar compact photonic band gap (UC-PBG) structures managed a 1.6 dB gain and 1 GHz bandwidth enhancement compared to that without AMC structures.

The thesis deals with the design and implementation of broadband and narrowband antennas and their applications in practical environment. In this thesis, a new concept for designing the UWB antenna is proposed based on the CRLH metamaterials and this UWB antenna covers a frequency range from 2.45 GHz to 11.6 GHz. Based on the design of the UWB antenna, another antenna is developed that can cover a very wide bandwidth i.e from 0.66 GHz to 120 GHz. This antenna can not only be used for UWB applications but also for other communication systems working below the UWB spectrum such as GSM, GPS, PCS and Bluetooth. The proposed antenna covering the bandwidth from 0.66 GHz to 120 GHz is by far the largest bandwidth antenna developed based on metamaterials. Wide band antennas are not preferred for sensing purpose as it is difficult to differentiate the received signals. A multiband antenna which can be used as a strain sensor for structural health monitoring is proposed. The idea is to correlate the strain applied along the length or width with the multiple resonant frequencies. This gives the advantage of detecting the strain applied along any direction (either length or width), thus increasing the sensing accuracy. Design and application of a narrow-band antenna as a temperature sensor is also presented. This sensor can be used to detect very high temperature changes (>10000C). This sensor does not require a battery, can be probed wirelessly, simple and can be easily fabricated, can withstand harsh environmental conditions.

Recently, there is great interest in achieving higher-level integration, higher data rates, and reduced overall costs. At millimeter-wave (mm-wave) bands, the wavelength is small enough to realize an antenna-on-chip (AoC), which is an ideal solution for high compactness and lower costs. However, the main drawback of AoC is the low resistivity (10 Ω-cm) Si substrate used in the standard CMOS technology, which absorbs most radio-frequency (RF) power that was supposed to be radiated by the on-chip antenna. Moreover, due to the high relative permittivity (11.9) and relatively large electrical thickness of the Si, higher order surface wave modes get excited, which further degrade the antenna radiation performance. In order to alleviate the above-mentioned issues with the low gain of AoC, a combination of an artificial magnetic conductor (AMC) surface, a high dielectric constant superstrate, and a Fresnel lens is presented in this work. The AMC is realized in standard CMOS technology along with the AoC, whereas the superstrate and lens are part of a smart packaging solution. The AMC surface can change wave propagation characteristics at the operating frequency to achieve in-phase reflection, resulting in gain enhancement by reducing the loss in the substrate. The high dielectric constant superstrate behaves as an impedance transformer between the Si substrate and air, thus enhancing the coupling to air. Finally, the Fresnel lens enhances the gain by focusing the electromagnetic (EM) radiation beam at the boresight. For AoC realization, a standard 0.18 μm CMOS process was utilized. A coplanar waveguide (CPW) fed monopole on-chip antenna at 71 GHz, along with the corresponding driving circuit, was designed and fabricated. The AMC enhances the gain by 3 dB. Since the chip needs to be packaged anyways, in this work, we optimize the package to provide further gain enhancement. This smart package, comprising a superstrate and a Fresnel lens, provides a gain enhancement of 16 dB. The overall combination of the optimized AMC surface, superstrate layer, and lens package can provide a gain enhancement of around 19 dB. Furthermore, the package has been realized through additive manufacturing techniques that ensure lower costs for the overall system.

The thesis presents a Sierpinski Carpet fractal antenna array designed at 24 GHz for automotive radar applications. Miniaturized, high performance and low cost antennas are required for this application. To meet these specifications a fractal array has been designed for the first time on Low Temperature Co-fired Ceramic (LTCC) based substrate. LTCC provides a suitable platform for the development of these antennas due to its properties of vertical stack up and embedded passives. The complete antenna concept involves integration of this fractal antenna array with a Fresnel lens antenna providing a total gain of 15dB which is appropriate for medium range radar applications. The thesis also presents a comparison between the designed fractal antenna and a conventional patch antenna outlining the advantages of fractal antenna over the later one. The fractal antenna has a bandwidth of 1.8 GHz which is 7.5% of the centre frequency (24GHz) as compared to 1.9% of the conventional patch antenna. Furthermore the fractal design exhibits a size reduction of 53% as compared to the patch antenna. In the end a sensitivity analysis is carried out for the fractal antenna design depicting the robustness of the proposed design against the typical LTCC fabrication tolerances.

This thesis is focused on the design of panel antennas for band 5,6 GHz. Antennas have been examined and optimized with a view to impedance, broadband and directional characteristics by using designing software CST Design Environment. Optimized antennas were produced, and their measured parameters achieved required values.

This work describes an electrically small antennas used for mobile devices in the ISM band. The aim of this work is to select an antenna for a universal transmitter/receiver working in the 868 MHz band. The work contains description of the universal transmitter/receiver, and a list of suitable antennas. Tolerance analysis is performed by numerical model. The proposed antenna is manufactured and measured.

Passive millimeter-wave (PMMW) imaging is a technique that allows the detection of inherent millimeter-wave radiation emitted by bodies. Since different bodies with varying properties emit unequal power intensities, a contrast can be established to detect their presence. The advantage of this imaging scheme over other techniques, such as optical and infrared imaging, is its ability to operate under all weather conditions. This is because the relatively long wavelengths of millimeter-waves, as compared to visible light, penetrate through clouds, fog, and sandstorms. The core of a PMMW camera is an antenna, which receives the electromagnetic radiation from a scene. Because PMMW systems require high gains to operate, large antenna arrays are typically employed. This mandatory increase of antenna elements is associated with a large feeding network. Therefore, PMMW cameras usually have a big profile. In this work, two enabling technologies, namely, Substrate integrated Waveguide (SIW) and Low Temperature Co-fired Ceramic (LTCC), are coupled with an innovative design to miniaturize the passive front-end. The two technologies synergize very well with the shielded characteristics of SIW and the high density multilayer integration of LTCC. The proposed design involves a novel multilayer power divider, which is incorporated in a folded feed network structure by moving between layers. The end result is an efficient feeding network, which footprint is least affected by an increase in array size. This is because the addition of more elements is accommodated by a vertical expansion rather than a lateral one. To characterize the feed network, an antenna array has been designed and integrated through efficient transitions.The complete structure has been simulated and fabricated. The results demonstrate an excellent performance, manifesting in a gain of 20 dBi and a bandwidth of more than 11.4% at 35 GHz. These values satisfy the general requirements of a PMMW system.

Formulations for analysis of printed antenna structures are derived and compared, to determine one to implemented in SuperNEC based on the efficiency of its numerical solution in terms of memory usage and solution time. SuperNEC is a software application for computing the response of electromagnetic structures to electromagnetic fields. SuperNEC cannot be used for simulation of printed antenna structures. This is because the formulation that is implemented in SuperNEC does not account for the effect of the substrates that the radiating elements of the antenna structure are printed on, and it is also not intended for antenna structures whose radiating elements are surfaces. Two MoM (Method of Moments) formulations and a FEM (Finite Element Method)-MoM formulation are presented, together with different models for the antenna feed. The FEM-MoM formulation is selected for implementation in SuperNEC because it is argued that it is likely to be more memory efficient when compared to the MoM formulations, and also that less time is required to fill the matrices resulting from the numerical solution of the formulation. The formulation is implemented in a stand alone software application, which will be integrated into SuperNEC. Numerical results that are computed using the software application are presented to illustrate correct implementation of the formulation. The results are compared to: an exact solution, results from another publication, and results computed using a different formulation. Good agreement is obtained in each case.