High efficiency dielectric resonator antenna using complementary ring resonator for bandwidth enhancement

A complementary ring resonator (CRR) technique is used to improve the bandwidth of the dielectric resonator antenna (DRA) while maintaining other parameters such as the efficiency and the gain. Parametric experiments were conducted in order to demonstrate the suggested antenna's working guideline. The bandwidth of the proposed Antenna is boosted by 769 percent as compared to the antenna without the CRR technique. The proposed antenna has high efficiency of 94 percent and a tiny dimension of around 30×30×12 mm. The suggested antenna has a frequency range from 2.61 to 3.65 GHz, which is suitable for S-band applications. Computer simulation technology (CST) was used to implement the design and obtain the results

Polarization reconfigurable antennas for space limited multiple input multiple output system

Wireless communication undergoes rapid changes in recent years. More and more people are using modern communication services, thus increasing the need for higher capacity in transmission. One of the methods that is able to meet the demands is the use of multiple antennas at both link ends known as Multiple Input Multiple Output (MIMO) system. However, for the space limited MIMO system, it is relatively difficult to accomplish good performance by using conventional antennas. Therefore, to further improve the performance offered by MIMO, Polarization Reconfigurable Antennas (PRAs) can be adopted. The diversity in polarization can be exploited to increase channel capacity. Moreover, the use of PRAs can also provide savings in terms of space and cost by arranging orthogonal polarized together instead of two physically space separation antennas. Here, single and dual port PRAs are proposed. Two techniques are deployed to achieve the PRAs are slits perturbation (switches on the radiating patch) and alteration of the feeding network (switches on the ground plane). Switching mechanism (ideal and PIN diode) is introduced to reconfigure the polarization between left-hand circular polarizations, right-hand circular polarizations, or linear polarization, operating at wireless local area network frequency band (2.4 – 2.5 GHz). Furthermore, by exploiting the odd and even mode of the coplanar waveguide structure, dual ports PRAs are realized with the ability to produce orthogonal linear polarization (LP) and circular polarization (CP) modes simultaneously. Good measured port polarization isolations (S21) of -16.3 dB and -19 dB are obtained at the frequency of 2.45 GHz for configuration A1 (orthogonal LP) and A2 (orthogonal CP), respectively. The proposed PRAs are tested in 2 x 2 MIMO indoor environments to validate their performances by using scalar power correlation method when applied as receiver in both line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. Channel capacity improvement has been achieved for spatial diversity (92.9% for LOS and 185.9% for NLOS) and polarization diversity (40.7% for LOS and 57.9% for NLOS). The proposed antenna is highly potential to be adopted to enhance the performance of the MIMO system, especially in dealing with multipath environment and space limited applications

Four-Element Biodegradable Substrate-Integrated MIMO DRA with Radiation Diversity

This article presents a four-element directional multiple input multiple output (MIMO) rectangular dielectric resonator antenna (RDRA) equipped with strategically placed copper reflector plates to enhance port isolation. This design aims to achieve an extended coverage range without compromising the coverage area. The proposed MIMO antenna is 3D printed using biodegradable polylactic acid to ensure mechanical robustness and then integrated with the substrate to prevent mis-mounting issues. The proposed design exhibits good MIMO characteristics, registering a 3-GHz bandwidth (4–7 GHz) for |S11|≤−10 dB and a minimum radiation gain of 7 dBi for all four RDRAs. The antenna demonstrates a rotation of radiation patterns for different ports, thus enabling beam formation in specific directions. With a beam width of 71.2°, the antenna covers all directions without any fade zones. The proposed 3D printed antenna offers simplicity, strong MIMO properties, and practicality for wireless communication systems, making it suitable for industrial, scientific, and medical band applications

Unequally spaced microstrip linear antenna arrays for fifth-generation base station

Wireless technology communication has been continuously evolving towards future fifth generation (5G), whereby multi-beam, multi-frequency, and low sidelobe characteristics are required in the mobile base station. However, the low sidelobe level of conventional mobile base station antenna led to more complex of feeding network design in order to give an adequate excitation coefficients (amplitude and phase) to array elements. Thus, the current base station antennas are difficult for wide frequency use due to frequency range is limited. Subsequently in this research, an unequally spaced microstrip linear antenna arrays is proposed. The radiation pattern synthesis for low sidelobe and grating lobes suppression over wide frequency use are investigated. In the first stage, a single antenna is designed at frequency 28 GHz followed by 16 element linear arrays in order to achieve the gain requirement for mobile base station antenna. Next, the design of antenna arrays with sidelobe reduction is proposed. Three configurations of linear antenna arrays are designed, which are equally spaced array (ESA), unequally spaced array 1 (USA 1) and unequally spaced array 2 (USA 2) at frequency f! = 28 GHz, f1 = 42 GHz and f2 = 56 GHz with a similar array aperture, in order to investigate the antenna performance in wide frequency use characteristics. USA 1 and USA 2 are having different center spacing of array (dc), which are dc(USA1) = 0.6 mm and dc(USA2) = 0.5 mm, respectively. The simulation results are obtained by using High Frequency Structure Simulator (HFSS). The good results were observed, where the performance of sidelobe reduction are constant even though the frequency changes. Due to the lack of measurement facilities at higher frequency than 18 GHz, the antenna arrays are redesigned at lower frequency, which are 12 and 18 GHz. In order to achieve a wide frequency operation, a wide frequency use of ESA?, USA 1? and USA 2? feeding network (which notation ? indicates that the frequency of 12 GHz is chosen as reference) are designed by using Advanced Design System (ADS). An equal line lengths (ln) with equal power ratio dividers were constructed. The sidelobe reduced from -13 dB for ESA? to -19 dB for USA 2?. The measurement of S-parameter and radiation pattern are performed using a vector network analyzer (VNA) and anechoic chamber, respectively. The measured results were presented and a good correlation with simulations was observed. From the observation, the sidelobe level and grating lobe suppression of USA 2? is reduced rather well and recommended for wide frequency band for 5G mobile base station antenna

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

Geometric Perturbation of Dielectric Resonator for Multifunctional MIMO Application

One of the recent concepts in communication systems is Multiple Input Multiple Output (MIMO) that has the potential to improve channel capacity by utilizing multiple transmitters and receivers. However, to reduce the implication on the required radiating element footprint, multiple antennas should be replaced with a single antenna that provides orthogonal multiple radiation patterns associated with the feeding ports. In addition, the proper use of frequency spectrum is possible when different modes of an antenna can be excited at the same frequency with polarization and radiation pattern orthogonality. This work proposes the idea of combining the multifunction device and multimode antenna with a dielectric resonator for a single band operation. The geometry of a cylindrical dielectric resonator has been perturbed to combine the radiating TM01δ and HEM11δ modes with the non-radiating mode TE01δ at the same frequency. The methodology of tuning several modes of DR with coupling mechanism and several practical concerns is mentioned in this work. The effect and rationalization of the introduced geometry perturbation parameters are presented. A prototype of the introduced concept is designed, fabricated and measured to prove the concept targeting the Wi-Fi MIMO applications. Afterwards, the designed device is used as a single element in a cascaded two element design where four different antennas work simultaneously at a single frequency with a filter. In summary, the main contributions of this work are: presenting the detailed procedure of geometry perturbation, including the metal placement on top of the resonator; proposing a coupling mechanism for tuning modes for simultaneous excitation; validating the introduced concept and methodology with a comparison between a simulated and measured prototype designed for MIMO applications; cascading two elements to obtain four independent antennas incorporating a filter

Design of antenna array and data streaming platform for low-cost smart antenna systems

The wide range of wireless infrastructures such as cellular base stations, wireless hotspots, roadside infrastructures, and wireless mobile infrastructures have been increasing rapidly over the past decades. In the transportation sector, wireless technology refreshes require constantly introducing newer wireless standards into the existing wireless infrastructure. Different wireless standards are expected to co-exist, and the air space congestion worsens if the wireless devices are operating in different wireless standards, where collision avoidance and transmission time synchronisation become complex and almost impossible. Huge challenges are expected such as operation constraints, cross-system interference, and air space congestion. Future proof and scalable smart wireless infrastructures are crucial to harmonise the un-coordinated wireless infrastructures and improve the performance, reliability, and availably of the wireless networks. This thesis presents the detailed design of a novel pre-configurable smart antenna system and its sub-system including antenna element, antenna array, and radio frequency (RF) frontend. Three types of 90° beamforming antenna array (with low, middle and high gain) were designed, simulated, and experimentally evaluated. The RF frontend module or transmit and receive (T/R) module was designed and fabricated. The performance of the T/R module was characterised and calibrated using the recursive calibration method, and drastic sidelobe level (SLL) improvement was achieved using the amplitude distribution technique. Finally, the antenna arrays and T/R modules are integrated into the pre-configurable smart antenna system, the beam steering performance is experimentally evaluated and presented in this thesis. With the combination of practical know-how and theoretical estimation, the thesis highlights how the modern smart antenna techniques that support most cutting-edge wireless technology can be adopted into the existing infrastructure with minimum distraction to the existing systems. This is in line with the global Smart City initiative, where a huge number of Internet of Things (IoT) devices being wired, or wireless are expected to work harmoniously in the same premises. The concept of the pre-configurable smart antenna system presented in this thesis is set to deliver a future-proof and highly scalable and sustainable infrastructure in the transportation market