LTE and GPS based Deca Band Printed Antenna for Cellular Mobile Handset Communication Applications

This paper presents novel mobile phone antenna for radiations simultaneously in ten frequency bands for applications of LTE (Long-Term Evolution), GPS (Global Positioning System), GSM (Global System for Mobile Communications), PCS (Public and Commercial Services), DCS (Distributed Control System), UMTS (Universal Mobile Telecommunications System) and WiMAX (Worldwide Interoperability for Microwave Access). The antenna demonstrates novel characteristics for resolving the challenge of simultaneous radiation capabilities for the GSM and GPS applications with frequencies of 850/900 and 1575 MHz respectively, along with resonances at frequency band of 700 MHz for LTE applications, 1800 and 1900 MHz for PCS and DCS applications, 2100 MHz for UMTS applications, 2400 and 2500 MHz for LTE applications and 3300 MHz for WiMAX applications with S11 = - 6 dB matching criteria (VSWR 3:1). The antenna architecture comprises top and bottom copper layers embedded with monopole radiating element, branch line, slots and various stub lines. The desired operating bands are achieved in a compact area with overall dimensions of 0.8x60x120 mm for the height, width and length respectively of the antenna providing suitable platform for mobile handset applications. Omni-directional radiation pattern characteristics are achieved throughout the range of frequencies by designing the proposed antenna in monopole configuration. Proposed antenna is fabricated and results for the surface currents, s-parameters and 3D (Three-Dimensional) gain plots are illustrated for the proof of concept

Study of a printed split-ring monopole for dual-spectrum communications

In this study, we present a low-profile dual-spectrum split-ring monopole that operates at industrial, scientific and medical (ISM) (2.45 GHz) band and ultrawideband (UWB) spectrum (3.1-10.6 GHz). We optimised the design for dual-band operations by using circular split-ring radiators. The coupling between both rings drives the structure to achieve quasi-resonance frequencies in the UWB spectrum. A small stub combines the two radiators and both behave as a single element that enables the antenna to resonate at ISM band 2.45 GHz. The antenna achieves the desired characteristics in terms of good impedance matching, radiation properties as well as other physical and practical requirements such as compact geometry, planar profile and easy fabrication. The very good agreement between the simulated and measured results show that the proposed antenna has the potential for dual-band application

MIMO antennas for mobile phone applications

Recent evolutions in wireless mobile communications have shown that by employing multiple inputs and multiple outputs (MIMO) technology at both the transmitter and receiver, both the wireless system capacity and reliability can be enhanced without the need for increasing the power transmitted or using more spectrum. Despite a considerable amount of research have been done on the design of MIMO and diversity handset antennas, the design of low profile, small footprint and multi-standard (wideband or multiband) diversity antennas on handset devices remains a challenging issue. Therefore, the purpose of this thesis is to present new antenna structures for handset MIMO and diversity applications. As the MIMO antenna design can be conducted either using multiple element antennas (MEA) or isolated mode antenna technology (IMAT), the work in this thesis is fallen in these two general design themes (areas). The first area under investigation concerns multiport antennas (IMAT antennas). It has the following two contributions: • A novel dual-feed water-based antenna is designed from a low cost liquid material with a very high dielectric constant (pure water ). The isolation between feeds is achieved by two back to back L-shaped ground plane strips. A prototype is made and the optimised diversity parameters are obtained, the results show that this design has a good diversity performance over the frequency range of 2.4 – 2.7 GHz. • A new and low profile (h = 3 mm) planar inverted-F antenna (PIFA) with a coplanar-feed is presented. It has a wideband response over the frequency range of 2.35 – 3.25 GHz. The design is based on a comparative study on the mutual coupling between different feed arrangements. As a result, the coplanar feed is employed in the proposed antenna; the polarization diversity is achieved by exciting two orthogonal radiation modes. The isolation between the feeds is achieved by an L-shaped ground plane slot. Both simulated and measured results demonstrate that the design is a very good candidate for mobile diversity and MIMO applications. The second investigation area concerns multiple element antenna (MEA) systems for wideband and multiband handset applications. It includes the following contributions: • Three antenna systems of the planar inverted-L (PILA) antenna (h = 5 mm) are employed for wideband handset diversity applications over the frequency range of 1.7 – 2.85 GHz: 1) The first design has a dual-element PILA in which both the pattern and spatial diversities are employed; one antenna element is located on the upper edge of the ground plane while the other is located on the lower edge. 2) The second design represents a more compact dual-element PILA antenna in which the two elements are placed on the same ground plane edge (collocated on the same edge). The antenna isolation is achieved using a parasitic decoupling element inserted between the two elements. A novel approach for the design of the parasitic decoupling element is proposed. It is based on stepped impedance resonator circuit theory. As a result, more space is saved with this design (footprint = 385 mm2) over the first design (footprint = 702 mm2). 3) The third design is a four-element PILA system in which two antenna pairs (one pair at the upper edge which the other pair is located on the lower edge on the system PCB). All the prototypes are made and evaluated; the results show excellent diversity performance over the applications in the frequency range of 1.7-2.7 GHz. • A dual-element hexa-band antenna is proposed for smartphone MIMO applications. It consists of two elements: a hexa-band metallic frame antenna and a hepta-band PILA antenna coupled with a meandered shorted strip as an internal antenna. The isolation is achieved due to the resulted orthogonal radiation patterns, especially, at 0.85 GHz. The optimized antenna is made and tested and the results show that this design covers a hexa-band and is particularly suitable for GSM850/ DCS1800/ PCS1900/ UMTS2100/ LTE2500/ LTE3600 smartphone applications

Multi-Band Small Antennas for Mobile Terminals

The thesis presents several novel ideas of designing electrically small antennas for mobile terminals such as mobile phones. As the fifth generation wireless systems (5G) is coming soon, radio signals at sub 6 GHz and millimetre-wave (mmWave) frequencies will be employed in mobile communication. In this thesis, the author concentrates on the antennas at sub 6 GHz, because the signals at sub 6 GHz will still play an important role in 5G mobile communication due to the advantage of signal penetration through buildings. The research areas consist of main antenna and multi-input multi-output (MIMO) antenna technology including decoupling techniques and MIMO antenna unit. First, a novel six-mode loop antenna as a main antenna is proposed for mobile phones. Loop antennas offer better user experience than monopole antennas, inverted-F antennas (IFA), and planar inverted-F antennas (PIFA) because of the unique balanced modes (1?, 2?, ...). However, the balanced modes also cause narrower bandwidth of loop antennas. In order to overcome the bandwidth problem, how to reach the upper limit of the existing operating modes and how to create more modes are explored. A novel monopole/dipole parasitic element, which operates at an unbalanced monopole-like 0.25? mode and a balanced dipole-like 0.5? mode, is firstly proposed. In order to validate the concept, one prototype with the dimension of 75×10×5 mm3 is designed, fabricated, and measured. The antenna is able to cover 660-1100 MHz, 1710-3020 MHz, 3370-3900 MHz, and 5150-5850 MHz, which is wide enough for almost all the service of mobile telecommunication systems. Then, a multimode decoupling technique is proposed for wideband/multiband isolation enhancement in compact volume. Although decoupling techniques have been researched for many years, multimode decoupling technique remains a great challenge for mobile terminals. One difficulty in achieving multi decoupling modes is that the operating modes of closely-packed decoupling elements have very strong mutual effect, which makes the tuning complicated and even unfeasible. Thus, in physical principle, a novel idea of achieving the stability of the boundary conditions of decoupling elements is proposed to solve the mutual effect problem; in physical structure, a metal boundary is adopted to realize the stability. One distinguished feature of the proposed technique is that the independent tuning characteristic can be maintained even if the number of decoupling elements increases. Therefore, wideband/multiband high isolation can be achieved by isolating multi decoupling elements. To validate the concept, two case studies are given. In a quad-mode decoupling design, the isolation is enhanced from 12.7 dB to > 21 dB within 22.0% bandwidth by using a 0.295?0×0.059?0×0.007?0 decoupling structure. Finally, a novel principle, namely differential/common mode (DM/CM) design, is proposed to achieve highly integrated MIMO antenna unit in mobile terminals. The inspiration comes from a dipole fed by a differential line which can be considered as differential mode (DM) feed. What will happen if the DM feed is transformed into a common mode (CM) feed? Some interesting features are found in the research. By symmetrically placing one DM antenna and one CM antenna together, a DM/CM antenna can be achieved. Benefitting from the coupling cancellation of anti-phase currents and the different distributions of the radiation currents, a DM/CM antenna can obtain high isolation and complementary patterns, even if the radiators of the DM and CM antennas are overlapped. Therefore, good MIMO performance can be realized in a very compact volume. To validate the concept, a miniaturized DM/CM antenna unit is designed for mobile phones. 24.2 dB isolation and complementary patterns are achieved in the dimension of 0.330?0×0.058?0×0.019?0. One 8×8 MIMO antenna array is constructed by using four DM/CM antenna units and shows good overall performance. The proposed idea of DM/CM design may be promising for other applications that need high isolation and wide-angle pattern coverage

Mutual coupling suppression in multiple microstrip antennas for wireless applications

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonMutual Coupling (MC) is the exchange of energy between multiple antennas when placed on the same PCB, it being one of the critical parameters and a significant issue to be considered when designing MIMO antennas. It appears significantly where multiple antennas are placed very close to each other, with a high coupling affecting the performance of the array, in terms radiation patterns, the reflection coefficient, and influencing the input impedance. Moreover; it degrades the designed efficiency and gain since part of the power that could have been radiated becomes absorbed by other adjacent antennas’ elements. The coupling mechanism between multiple antenna elements is identified as being mainly through three different paths or channels: surface wave propagation, space (direct) radiation and reactive near-field coupling. In this thesis, various coupling reduction approaches that are commonly employed in the literature are categorised based on these mechanisms. Furthermore, a new comparative study involving four different array types (PIFA, patch, monopole, and slot), is explained in detail. This thesis primarily focuses on three interconnected research topics for mutual coupling reduction based on new isolation approaches for different wireless applications (i.e. Narrowband, Ultra-wide-band and Multi-band). First, a new Fractal based Electromagnetic Band Gap (FEBG) decoupling structure between PIFAs is proposed and investigated for a narrowband application. Excellent isolation of more than 27 dB (Z-X plane) and 40 dB (Z-Y plane) is obtained without much degradation of the radiation characteristics. It is found that the fractal structures can provide a band-stop effect, because of their self-similarity features for a particular frequency band. Second, new UWB-MIMO antennas are presented with high isolation characteristics. Wideband isolation (≥ 31 dB) is achieved through the entire UWB band (3.1-10.6 GHz) by etching a novel compact planar decoupling structure inserted between these multiple UWB antennas. Finally, new planar MIMO antennas are presented for multi-band (quad bands) applications. A significant isolation improvement over the reference (≥ 17 dB) is achieved in each band by etching a hybrid solution. All the designs reported in this thesis have been fabricated and measured, with the simulated and measured results agreeing well in most cases

Investigations on some compact wideband fractal antennas

Today’s small handheld and other portable devices challenge antenna designers for ultrathin, and high performances that have the ability to meet multi standards. In the context, fractal geometries have significant role for antenna applications with varying degree of success in improving antenna characteristics. In this thesis, we have investigated several wideband fractal monopole antennas. This work starts with design and implementation of Koch fractal, hybrid fractal, sectoral fractal, semi-circle fractal monopole antennas with discussion, covering their operations, electrical behavior and performances. The performances of these designs have been studied using standard simulation tools used in industry/academia and are experimentally verified. Frequency reconfigurable Koch snowflake fractal monopole antenna is also introduced. The present antenna can be used as an array element and has a wideband frequency of operation. A square Sierpinski monopole antenna has been designed, which is suitable for use in indoor UWB radio system and outdoor base station communication systems. Technique for obtaining a band stop function in the 5-6 GHz frequency band is numerically and experimentally presented. In addition to examining the performance of UWB system, the transfer function and waveform distortion are discussed. Finally, fractal antenna for array with MIMO environment is developed for mobile communication devices. Aim of this work is to achieve the acceptable performances in terms of isolation, envelope correlation coefficient, capacity loss, radiation patterns and efficiency. Furthermore, a wideband feed network prototype based on a modified Wilkinson power divider is designed. The designed feed network has been used in constructing 2-element and 4-element linear antenna arrays for high gain. This research work has addressed the effectiveness of fractal geometries in antenna and to bring-out the true advantages of their in antenna engineering

Design and analysis of wideband passive microwave devices using planar structures

A selected volume of work consisting of 84 published journal papers is presented to demonstrate the contributions made by the author in the last seven years of his work at the University of Queensland in the area of Microwave Engineering. The over-arching theme in the author’s works included in this volume is the engineering of novel passive microwave devices that are key components in the building of any microwave system. The author’s contribution covers innovative designs, design methods and analyses for the following key devices and associated systems: Wideband antennas and associated systems Band-notched and multiband antennas Directional couplers and associated systems Power dividers and associated systems Microwave filters Phase shifters Much of the motivation for the work arose from the desire to contribute to the engineering o