Performance Improvement of Dense Dielectric Patch Antenna using Partially Reflective Surfaces

Recently, millimeter-wave (MMW) band is being considered as the spectrum for future wireless communication systems. Several advantages are achieved by utilizing the millimeter-wave range, including high gain with large available bandwidth, compact size, and high security. Nevertheless, attenuation loss may restrict wireless communication systems’ transmission range. Meanwhile, printed antenna technology has gained the attention of antenna designers’ due to its low profile and ease of fabrication. High-gain antennas are very desirable as a critical part of MMW systems. Designing millimeter wave antennas with high gain characteristics would be a significant advantage due to their high sensitivity to atmospheric absorption losses. Moreover, planar configurations are required in many applications, such as for wireless communication. The main goal of this thesis is to design and propose state of the art designs of Fabry Pérot Cavity antenna (FPCA) designs with several types of superstrates to achieve high gain, wide bandwidth, and high efficiency to satisfy the requirements of today’s advanced wireless communication systems. A dense dielectric patch (DD) antenna is used as the main radiator and designed to operate at 28 GHz. The thesis presents several contributions related to the design and analysis of FPC antennas using several types of superstrates. The first research theme of this thesis has two parts. The first part presents a holey dielectric superstrate applied over a 2×2 dense dielectric square patch antenna array to enhance the gain, improve the bandwidth and efficiency, as well as to reduce the side lobe levels (SLLs). A dense dielectric patch replaces the metallic patch and is used as a radiated element. The measured results show a high gain of 16 dBi, with radiation efficiency of about 93 %, wide bandwidth of 15.3 %, and a reduced SLL. The second part focusses on a partially reflective surface (PRS) unit cell composed of two thin perforated dielectric slabs. The effect of the thicknesses of the unit cell dielectric slabs is discussed in detail. An array of the proposed PRS unit cell is applied over a dense dielectric square patch antenna array to broaden the bandwidth and to enhance the gain as well. The measured results exhibit a 3 dB gain bandwidth of 27 % with a high gain of 16.8 dBi. The second research theme presents an effective method to design a tapered superstrate of an FPC antenna with a DD patch element. This type of superstrate is designed to correct the phase above the superstrate to be almost uniform. The proposed single-layer perforated tapered superstrate is constructed by tapering the relative permittivity to be high in the center of the superstrate slab and then decrease gradually as it moves towards the edges. This tapered relative permittivity is then applied over a single DD patch antenna. The proposed antenna exhibits good performance in terms of the antenna gain and bandwidth. The antenna gain becomes flat and as high as 17.6 dBi. The antenna bandwidth is about 16 %, and the side lobe level of the antenna is very promising. A third theme presents the implementation and design of a high gain dense dielectric patch antenna integrated with a frequency-selective surface (FSS) superstrate. A 7×7-unit cell is used to build the superstrate layer, and applied above the high DD patch antenna. A modified unit cell is proposed to generate a positive reflection phase with high reflection magnitude within the frequency design in order to broaden the antenna bandwidth. A bandwidth of 15.3 % with a high gain of 16 dBi is obtained. Finally, a high gain linearly polarized (LP) substrate integrated waveguide (SIW) cavity antenna based on a high-order mode is implemented, fabricated, and tested. A TE440 mode is excited at 28 GHz. In this design, 4×4 slots are cut into the top metal of the cavity, where each slot is placed above each standing wave peak. These slot cuts contributed to a high gain of 16.4 dBi and radiation efficiency of about 96 %. The LP SIW cavity antenna was then integrated with a linear-to-circular polarization converter developed as a high gain circularly polarized (CP) SIW cavity antenna with high gain and high radiation efficiency of 16 dBi and 96 %, respectively

Study of Mm-wave Microstrip Patch Array on Curved Substrate

A millimetre wave rectangular microstrip patch antenna array for fifth generation communications (5G) applications is presented. With the increase in demand for high data rates and capacity, there is a need to include mm-Wave frequencies for 5G. The 4×2 patch array is simulated and fabricated on a Rogers RT/Duroid 5880 substrate with a thickness of 0.25 mm. The effects of bending the substrate on the antenna performance are also presented. The experimental results show a fractional bandwidth and gain of more than 3% and 16.1 dBi, respectively

Metasurface-based wideband MIMO antenna for 5G millimeter-wave systems

This paper presents a metasurface based multiple-input multiple-output (MIMO) antenna with a wideband operation for millimeter-wave 5G communication systems. The antenna system consists of four elements placed with a 90 degree shift in order to achieve a compact MIMO system while a 2× 2 non-uniform metasurface (total four elements) is placed at the back of the MIMO configuration to improve the radiation characteristics of it. The overall size of the MIMO antenna is 24× 24 mm2 while the operational bandwidth of the proposed antenna system ranges from 23.5-29.4 GHz. The peak gain achieved by the proposed MIMO antenna is almost 7dB which is further improved up to 10.44 dB by employing a 2× 2 metasurface. The total efficiency is also observed more than 80% across the operating band. Apart from this, the MIMO performance metrics such as envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CCL) are analyzed which demonstrate good characteristics. All the simulations of the proposed design are carried out in computer simulation technology (CST) software, and measured results reveal good agreement with the simulated one which make it a potential contender for the upcoming 5G communication systems.This work was supported in part by the Universidad Carlos III de Madrid and the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant Agreement No 801538, and in part by the the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE) under Grant RTI2018-095499-B-C31

Metasurface-Based Wideband MIMO Antenna for 5G Millimeter-Wave Systems

This paper presents a metasurface based multiple-input multiple-output (MIMO) antenna with a wideband operation for millimeter-wave 5G communication systems. The antenna system consists of four elements placed with a 90 degree shift in order to achieve a compact MIMO system while a 2 x 2 non-uniform metasurface (total four elements) is placed at the back of the MIMO configuration to improve the radiation characteristics of it. The overall size of the MIMO antenna is 24 x 24 mm(2) while the operational bandwidth of the proposed antenna system ranges from 23.5-29.4 GHz. The peak gain achieved by the proposed MIMO antenna is almost 7dB which is further improved up to 10.44 dB by employing a 2 x 2 metasurface. The total efficiency is also observed more than 80% across the operating band. Apart from this, the MIMO performance metrics such as envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CCL) are analyzed which demonstrate good characteristics. All the simulations of the proposed design are carried out in computer simulation technology (CST) software, and measured results reveal good agreement with the simulated one which make it a potential contender for the upcoming 5G communication systems

Metasurface based MIMO microstrip antenna with reduced mutual coupling.

Masters Degree. University of KwaZulu- Natal, Durban.In this thesis, a negative permeability (μ) metasurface is used to reduce the mutual coupling of a 2-port Multiple-Input Multiple-Output (MIMO) rectangular inset fed microstrip antenna. That was designed using the transmission model of analysis, simulated and optimized using CST microwave studio. The microstrip antenna that operates at the (5.9-6.1) GHz band is designed for 5G applications, at the extended 6 GHz band (5.925-7.125) GHz. The extended band was chosen because of its new additional spectrum, which results in less noise interference. Three metasurface wall based antenna designs and two metasurface superstrate based antenna designs are conducted. The metasurface wall based antenna designs are formulated by placing a metasurface wall vertically between the two radiating antenna elements. The metasurface superstrate based antenna designs are formulated by suspending a metasurface superstrate above the 2-port microstrip antenna. Both the metasurface wall and superstrate are made up metasurface unit cells, which are formulated by periodic split ring resonators printed on a FR-4 dielectric substrate. The metasurface cells are responsible for introducing a negative permeability medium, which converts the electromagnetic propagating waves into evanescent hence rejecting mutual coupling. In the first metasurface based antenna design, a single metasurface wall is vertically placed between the two microstrip antenna elements. A slight increase of 0.5 dB in mutual coupling is observed. In the second design, a double metasurface wall is vertically placed between the two antenna elements. A mutual coupling reduction of 11 dB is achieved. In the third design a triple metasurface wall is also placed between the two antenna elements, a mutual coupling reduction of 25 dB and up to 17 % bandwidth enhancement is achieved. In the fourth design a single metasurface superstrate is suspended above the 2-port microstrip antenna. A mutual coupling reduction of 32 dB is achieved. Lastly, in the fifth design a metasurface superstrate is also suspended above the 2-port microstrip antenna. A mutual coupling reduction of 22 dB, a 38% bandwidth enhancement and a 2.09 dB gain enhancement is achieved

Gain enhancement of microstrip patch antenna using artificial magnetic conductor

The paper presents an artificial magnetic conductor (AMC) structure to enhance the gain of the double microstrip patch antenna. By placing this kind of metamaterial in between the two Rogers RT5880 substrates, the antenna achieved lots of improvement especially in terms of size miniaturization, bandwidth, return loss, gain and efficiency. The antenna is intended to operate at 16 GHz where the prospect fifth generation (5G) spectrum might be located. Integration of AMC structure into the proposed antenna helps to improve nearly 16.3% of gain and almost 23.6% of size reduction

A Survey: Massive MIMO for next Generation Cellular Wireless Technologies

The rapid development of MIMO technology in the area of wireless communications is to setting up of base stations with large number of antennas to improvements in energy and spectral efficiency. In this paper a detailed survey on massive technology, its advantages and comparison with existing method are proposed. The Long Term Evolution (LTE) has been designed to support only packet-switched services and is aimed to provide IP connectivity between UE and eNodeB. As we move forward to5G becoming more promising next generation technology with increase in capacity, reduced latencies, support of very high frequencies (mmWave) with a smaller size single antenna, smaller the aperture for receiving energy. To overcome this small aperture on receiver side at high frequency, we need to use a large number of transmission antenna. This would be the main reason to use the Massive Multiple Input Multiple Outputs (MIMO).This paper focused on the massive MIMO performance, the gain, and return losses of different antennas operating at different frequencies

High gain wideband microstrip patch antennas with defected ground structure for Sub-6 GHz 5G communications.

Masters Degree. Unversity of KwaZulu- Natal, Durban.5G communication utilizes the two frequency ranges i.e. frequency range 1 (FR1) and frequency range 2 (FR2). The FR1 is the low frequency band with the frequency range from 450 MHz to 6 GHz. As FR1 contains the frequency range upto 6 GHz, it is also known as sub-6 GHz frequency band. The FR2, known as mm-wave frequency range, uses the frequencies above 24 GHz. The lower frequency including electromagnetic (EM) waves can travel farther as these are less a ected by the weather such as rain, snow etc. The low frequency EM waves can penetrate the solid objects like buildings etc. The sub-6 GHz 5G radio band will handle the wider bandwidth needed for high speed 5G communication devices. This research work presents the design of 5 GHz microstrip patch antennas for use in sub-6 GHz 5G communication. Antennas designed for 5G network must have high gain and necessary wideband capabilities to handle the large data requirements at high speed. This research proposes the design of a high gain rectangular microstrip patch antenna (HGRMPA) for use in sub-6 GHz 5G communication. A HGRMPA, that utilizes the patch with T-shaped slot, is designed. The defected ground structure (DGS) technology is used to improve the performance of the HGRMPA. The DGS of the proposed HGRMPA consists a C-shaped slot. The C-shaped slot along with cuts at its upper and lower parts is incorporated in the ground plane to further improve the performance of the HGRMPA. A re ective plate is placed at the back of the proposed HGRMPA to reduce the side lobes and back lobes produced by the antenna. This will improve the main lobe of the radiated signal and the gain of the HGRMPA. The proposed HGRMPA is fed using inset feeding technique and the antenna is mounted on the FR-4 epoxy substrate. The size of the proposed HGRMPA is 28:03 23:45 5:35 mm3 and it provides the maximum gain and maximum directivity of 5.49 dB and 7.12 dB, respectively. The bandwidth of the proposed HGRMPA is from 4:775 GHz to 5:049 GHz, which covers the 4:8 GHz5 GHz sub-6 GHz 5G communication band. Further, a high gain wideband microstrip patch antenna (HGWBMPA), using partial ground plane with triangular strip, is also presented. The proposed HGWBMPA operates in the sub-6 GHz 5G wireless networking band. The HGWBMPA utilizes the re ective plate to reduce the development of the back lobes and increasing the gain. The inset feed technique is used to feed the antenna and the antenna is mounted on the FR-4 epoxy substrate. The proposed design is simulated and optimized with commercially available EM software i.e. CST studio suite. The size of the proposed HGWBMPA is compact with the patch dimension of 18:43 13:85 mm2. The maximum gain, maximum directivity ande ciency of the HGWBMPA are 6:21 dB, 7:56 dB and 78%, respectively. The proposed HGWBMPA works from 4:921 GHz to 5:784 GHz, which covers the 4:9 GHz - 5:8 GHz sub-6 GHz 5G communications range

Substrate Integrated Waveguide Based Millimeter Wave Antennas

Antennas those operating at millimeter-wave (mm-wave) frequencies (30 - 300 GHz) are more advantageous than operating at less than 6 GHz, due to a reduction in antenna physical dimensions, an increase in the data transfer rate, and reduction in latency. However, the electromagnetic waves propagating in free space at mm-wave frequencies experience significant propagation path loss due to the atmospheric absorption and rain attenuation. Therefore, high-gain antennas are preferred to compensate for path loss and to increase the range of wireless communication. Also, transmission lines such as microstrip, and coplanar waveguides incur high radiation losses at mm-wave frequencies. Hence, to minimize losses, a planar waveguide known as a substrate integrated waveguide (SIW) is preferred. Besides, at mm-wave frequencies, circularly polarized (CP) waves are preferred over linearly polarized (LP) waves as these waves reduce multi-path effects at the receiver. The objectives of this thesis are to design high-gain linearly, and circularly polarized antennas based on SIW at the mm-wave frequency 30 GHz. The proposed antenna models were designed, simulated, and analyzed using CST software. The antenna prototypes were fabricated and measured for the reflection coefficient, gain, and principal plane radiation patterns. In this thesis, we are proposing two single element antennas, a linear to circular wave polarizer, and an array antenna. At first, we present, a planar, cylindrical sector-substrate integrated waveguide (CS-SIW) narrow slot antenna. The impedance bandwidth of this antenna is 10.87% which is approximately equivalent to 4 GHz of bandwidth at 30 GHz, and the antenna gain ranges from 8.33 to 8.84 dB within the impedance bandwidth. Further, to improve the gain, an engineered substrate is constructed on top of the CS-SIW slot antenna. The impedance bandwidth of the modified antenna is 10.42% - also, the gain ranges from 10.5 to 11.44 dB over the impedance bandwidth, which implies an increase in the gain from 2.1 to 2.7 dB when compared with the gain of CS-SIW slot antenna. Also, we propose a three-layered meander-line polarizer at 30 GHz which transforms linearly polarized waves to circularly polarized waves for the CS-SIW slot antenna. Lastly, we present, a 1 × 8 CS-SIW slot antenna array with a superstrate to achieve a high-gain LP antenna. The impedance bandwidth of the antenna is 10%. The gain of the array antenna integrated with a superstrate layer varies from 21.35 to 22.95 dB over the impedance bandwidth

Two dimensional switched beam antenna at 28 GHz for fifth generation wireless system

Fifth generation (5G) wireless system is expected to enable new device-to-device (D2D) and machine-to-machine (M2M) applications that will impact both consumers and industry. Moreover, for efficient M2M communication, both one dimensional (1-D) and two dimensional (2-D) beam switching is highly needed for high data-rate wireless radio links. A planar array with 2-D beam switching capabilities is highly desirable in 5G system. This thesis proposes a new technique of achieving simple and cost effective 2-D beam switching array antenna at 28 GHz for 5G wireless system. The technique involves lateral cascading of Butler matrix (BM) beamforming network (BFN). However, designing a planar BM at 28 GHz that will allow K-connector is not a trivial issue because the distances between the ports are X/4 electrical length apart. Nevertheless, two branch line coupler (BLC) with unequal ports separation at 28 GHz on a single substrate are designed and applied to design 1-D switched beam antennas based on BLC and 4 * 4 BM. Then two of these antennas are laterally cascaded to achieve 2-D beam switching antenna. This novel concept is the basis for choosing BM BFN in the design. The proposed 1-D array antennas on BLC and BM have wide measured impedance bandwidth of 18.9% (5.3 GHz) and 21.7% (6.1 GHz) and highest gain of 14.6 dBi and 15.9 dBi, respectively. The 2-D switched beam antenna on cascaded BLC has highest realized gain of 14.9 dB, radiation efficiency of 86%, 86.8%, 85.5%, and 83.4% at ports 1 to 4, respectively. The switching range of from -25o to +18° in the x-z plane and from -18o to 24o in the y-z plane, while the 2-D switched beam antenna based on cascaded 4 * 4 BM has switching range of -41o to 43o in the x-z plane and -43o to 42o in the y-z plane with highest realized gain of 14.4 dBi. The proposed antennas have great potentials for 5G wireless communication system applications