Small Dual Polarized UWB Antenna and Its Array Analysis for 5G/6G Applications

Ultra wide band - Multiple Input Multiple Output antenna technology provides higher data rates and the combination of the ultra wide band (UWB) and the multiple input multiple output (MIMO) technologies provides a solution for the demand of still higher data rates i.e. in excess of 3 Gb/sec in the future. As the antenna technologies are improving, the size of the MIMO antenna is growing smaller and smaller. Placing the antenna elements in such close proximity increases the coupling between them. Various isolation techniques have to be introduced between the antenna elements to decrease the coupling and to improve the isolation. A study of the various isolation enhancement techniques have been made in this review. It analyses the various isolation enhancement methods such as using orthogonal polarization, parasitic elements, varied decoupling structures, defected ground structures (DGS), neutralization line (NL) and finally by using metamaterials. Metamaterials is a technology to perk up the isolation between the antenna elements. Split ring resonator (SRR) behaves as a metamaterial and it is used as an isolation mechanism in this study. The antennas are simulated and the results are compared. The method using parasitic elements gives the highest isolation of 35 dB and it is 5 dB better than the methods using orthogonal polarization and using the decoupling structure. The performance of all the antennas satisfies the conditions for minimum isolation. The envelope correlation coefficient is nearly zero in all the antennas and it implies good diversity performance. The diversity gain is also calculated for the various antennas and it satisfies good diversity performance. The bandwidth of the antennas is in the UWB frequency range and they have a fractional bandwidth above the required value of 1.09. The capacity loss for all the antennas is very low and the antennas using defected ground structure and the decoupling structure gives very low capacity loss.

Highly selective multiple-notched UWB-MIMO antenna with low correlation using an innovative parasitic decoupling structure

In this report, a compact antenna system with dual-band-notched characteristics is proposed for ultra-wideband (UWB) multiple-input multiple-output (MIMO) applications. Two antenna elements are placed side by side and fed with matched microstrip lines on a substrate with an area of 35 × 30 mm2. Notched characteristics at WiMAX (3.4–3.6 GHz) and WLAN (5.725–5.825 GHz) have been achieved using complementary split ring resonator (SRR) slots etched in both the antenna elements. Electromagnetic isolation between the two elements close to each other is achieved using a ground T-stub and slots etched in the ground plane. Antenna system has been tested and measured results are close to the desired ones. Measured isolation >20 dB is obtained in most of the UWB bands. The proposed antenna system meets the requirements well for MIMO applications.

This thesis is based on the realisation that no analytical theory of loop antennas and rings exists that is at once applicable to the Radio Frequency (RF), Micro-wave (MW), TeraHertz (THz), Infra-red (IR), and Optical (OR) regions. Nor is there any Electrical Engineering circuit model, rigorously developed from the results of that theory, that generates results which match numerical simulations and experimental work in the literature across all of these regimes. This thesis fills that gap. Maxwell’s equations for perfectly conducting, closed circular loops are presented, and then solved, using standard RF andMWantenna theory. The governing equation is then extended to include real, lossy metals with focus on the noble metals, gold, silver and copper. The solution to the extended equation yields results for rings in the THZ, IR and OR. Next, the governing equation is extended to include a single impedance on the periphery. The solution is studied using a capacitive reactance, in particular. These results are compared to simulations of illuminated rings with a single gap, and a relationship is developed between the width of the gap and its capacitive reactance. Primary results are these: • An analytical set of mathematical functions derived from Maxwell’s equations now exist that give the current distribution on closed and single gapped loops at all frequency regimes from the RF through OR, constructed of any metal for which the index of refraction is known. • A detailed RLC circuit model has been derived from these functions, accurate at all frequency bands, from which the total R, L and C of the loop at any frequency or wavelength, and the R, L and C of any modal resonance, can be calculated. The model yields the functions R(w), L(w), C(w) from which radiation resistance, power loss, radiation efficiency, radar cross-section, and the quality factor (Q) of any resonance can be calculated. • The input impedance of the circuit model representing the loop can be calculated as a function of wavelength for closed loops and single gap loops. • The introduction of a single gap in the periphery of a loop will cause a very high-Q resonance in the sub-wavelength region. This is due to the zero-order mode inductance of the loop resonating with a combination of the gap capacitance and the closed loop capacitance. The Q is on the order of several thousand. • Gap width and capacitance value of the gap are closely related. However, none of the simple models suggested in the literature, such as the flat-plate capacitance model, generates the correct relationship, at least for gaps in rings.

In this paper, an integrated multiple-input-multiple-output (MIMO) antenna system is presented that consists of 4-element ultra-wide-band (UWB) antenna and 4-element frequency reconfigurable antenna system. Both antenna elements are designed on the same substrate. The frequency reconfigurable communication antenna is a slot-based structure that achieves frequency reconfigurability over wide range from 1.4 to 2.2 GHz using varactor diode tuning. The UWB antenna can be utilized to sense the frequency spectrum as well as operate as a MIMO antenna system over a frequency band from 1.4 to 4.85 GHz. The frequency reconfigurable antenna is loaded with an annular split ring resonator (SRR) for size reduction. The simulated and measured results are in good agreement. The total size of antenna is compact with dimensions of 150 × 200 × 1.52 mm3. The proposed antenna is suitable to be used in tablet PCs and laptops with cognitive radio capabilities.

A compact split ring resonator (SRR) loaded, coplanar waveguide (CPW) fed ultrawideband (UWB) circular monopole antenna having reconfigurable characteristics is presented in this paper. The SRRs are placed symmetrically on the back side of the CPW fed planar monopole antenna as shown in Fig. 1. The propagating signal excites the magnetic resonance of the SRR which prohibits transmission around the frequency determined by the SRR's geometry and the constitutive parameters of the substrate and thereby yields in weak radiation around that frequency. However, placing a shunt wire along lateral direction (x axis) in the x-y plane along the CPW line thereby effectively shorting the CPW yields interesting characteristic. When the shorting wires are placed parallel to the plane and located along the center of the SRR separated by the dielectric thickness, h, the structure exhibits complimentary characteristics. This simple but insightful idea is used to reconfigure the planar UWB monopole antenna into a narrow band antenna radiating at the resonance frequency of the SRR.

Multiple-input multiple-output (MIMO) scheme refers to the technology where more than one antenna is used for transmitting and receiving the information packets. It enhances the channel capacity without more power. The available space in the modern compact devices is limited and MIMO antenna elements need to be placed closely. The closely spaced antennas undergo an undesirable coupling, which deteriorates the antenna parameters. In this paper, an ultra wide-band (UWB) MIMO antenna system with an improved isolation is presented. The system has a wide bandwidth range from 2–13.7 GHz. The antenna elements are closely placed with an edge to edge distance of 3 mm. In addition to the UWB attribute of the system, the mutual coupling between the antennas is reduced by using slotted stub. The isolation is improved and is below −20 dB within the whole operating range. By introducing the decoupling network, the key performance parameters of the antenna are not affected. The system is designed on an inexpensive and easily available FR-4 substrate. To better understand the working of the proposed system, the equivalent circuit model is also presented. To model the proposed system accurately, different radiating modes and inter-mode coupling is considered and modeled. The EM model, circuit model, and the measured results are in good agreement. Different key performance parameters of the system and the antenna element such as envelope correlation coefficient (ECC), diversity gain, channel capcity loss (CCL) gain, radiation patterns, surface currents, and scattering parameters are presented. State-of-the-art comparison with the recent literature shows that the proposed antenna has minimal dimensions, a large bandwidth, an adequate gain value and a high isolation. It is worth noticeable that the proposed antenna has high isolation even the patches has low edge-to-edge gap (3 mm). Based on its good performance and compact dimensions, the proposed antenna is a suitable choice for high throughput compact UWB transceivers.

Phase-shift measurement method, a new approach to the phased array antenna measurement, is studied in this paper, to solve the problem of the fast measurement and identifying malfunction elements in phase array antennas. With the phased array antennas and the probe both fixed, the method made the measurement high efficient by researching the optimization algorithms of phase distribution combined with the characteristics that the phase-shift state of each phase shifter is controllab le in the phased array antennas and using some known credible information. The common malfunctions of the phased array antennas and the theory of the fast measurement and identifying malfunction elements by the phase-shift measurement method are both introduced in detail. It is proved to be correct and efficient by the s imulation of the measurement process of a phased array antenna model using this method. Study shows it is a practical method, especially suited to the fast measurement and identifying ma lfunction elements of large-scale phased array antennas.

In view of the drawbacks of currently adopted breast cancer treatment techniques, novel method is needed to accomplish safe and efficient breast cancer therapy. Focused microwave breast hyperthermia (FMBH) is a promising breast cancer treatment approach. The FMBH mechanism uses a phased antenna array to deliver microwave power into a breast and takes advantage of beamforming to focus microwave fields at a tumor. By this manner, the tumor is efficiently heated while the rest normal tissues receive less energy. This work studies the effect of number of elements in the phased array antenna used in FMBH by computational modeling. Simulations are conducted and obtained results prove that using more antennas can enhance the focusing. This work is meaningful for related areas of microwave hyperthermia.

Since the first Report and Order by the Federal Communications Commission (FCC) authorized the unlicensed use of ultra wideband (UWB) which must meet the emission masks on February 14, 2002 [1], both industry and academia have paid much attention to R&D of commercial UWB systems. Among UWB system design, the UWB antenna is the key component. Recently, a considerable amount of researches have been devoted to the development of the UWB antenna for its enabling high data transmission rates, low power consumption and simple hardware configuration in communication applications such as radio frequency identification devices, sensor networks, radar, location tracking, etc. Nowadays, the planar printed antenna fed with a microstrip line or a coplanar waveguide (CPW) has received much attention due to its high radiation efficiency and compact size and can be easily integrated with the other circuit. However, compared to the microstrip-fed antennas, the CPW-fed antennas are very good candidates since the feed line and slots are on one side of the substrate [2]. In order to obtain ultra wideband, the different optimum metal radiation patch geometries have been developed, like fork shape [3], elliptical shape [4], square shape [5], spade shape [6], circle shape [7], or made some modifications about the radiation patch [8]. Besides, over the designated frequency band, there exist some narrow bands for other communication systems, such as WiMAX operating in the 3.3 to 3.6 GHz band, and WLAN operating in the 5.15 to 5.825 GHz. They may cause communication interference with the UWB system. To solve this problem, it is desirable to design antennas with band notched characteristics to minimise potential interference. Several UWB antennas with frequency band notched function have been reported recently. The reported antennas are generally embedded with a half-wavelength structure such as a ω-shaped slot [2], a Ushaped slot [4], a C-shaped slot [8], or a V-shaped slot [9]. But most reported antennas were designed with only one notched band, mainly discussed on WLAN frequency band 5.15 to 5.825 GHz. UWB antennas with dual notched band were recently reported. In [10], the dual notched bands were formed by two nested C-shaped slots embedded in the bevelled patch. A pair of asymmetrical spurlines on the feedline was used to achieve dual notched band in [11]. A recently reported antenna has been designed by making use of two split resonant rings (SRR) to obtain dual band-notched characteristics [12]. Nevertheless, the geometry of the SRR structure is relatively complex. In this paper, a CPW-fed novel planar ultra-wideband antenna with dual band-notched characteristics is introduced. In order to obtain ultra wideband, some modifications about

In this manuscript, a 2x2 highly isolated quad-band suppressed Ultra-Wide band Multiple input multiple output antenna is analyzed. The proposed design employs two antenna elements is arranged in orthogonal manner by deploying polarization diversity technique. Ameliorated frequency selectivity of notch bands can be accomplished by loading each antenna element with three U-shape slots and a split ring resonator (SRR) exhibit band suppression of 3.41-4.07GHz, 4.41-4.76 GHz, 5.21-5.64GHz and 6.92-8.63GHz to surmount the possible intrusion from 5G, INSAT, WLAN and X-band for satellite communication. The suggested antenna works in the frequency range from 2.9-12GHz which is suitable for ultra-wide band applications. Simulation is done to analyze the response of the suggested antenna with respect to notch frequencies, current distributions, Peak gain, radiation patterns, envelope correlation coefficient and diversity gain.

This paper presents a rectangular antenna with a dual-band notch for Ultra-Wideband (UWB) applications. The antenna in this configuration has a surface area of 22×34 mm2. A single rectangular split ring resonator (SRR) is etched on the radiation patch element of the UWB antenna to create the first notch band with a resonant frequency of 3.508 GHz to cancel and eliminate the interference with WiMAX and 5G applications. The second notch band with a resonant frequency of 5.213 GHz, is created by inserting two C-shaped parasitic elements around the feedline of the system to cancel the interference with WLAN applications. The impedance bandwidth of the proposed antenna is (2.87–up to 12) GHz, which ensures coverage of UWB. The realized gain value is more than 3.9 dB over the entire UWB range, but it decreases below -2.3 and -8.5 dB within the first and second notch bands, respectively. The result indicated that the presented antenna has a good radiation properties and an omnidirectional radiation pattern that is appropriate for portable devices. Moreover, the experimental measurement results of the fabricated antenna are in good agreement with the simulation results.

2 X 2 dual slant polarized multiple input multiple output (MIMO) antennas with reduced mutual coupling is presented for polarization and spatial diversity. The design of printed periodic array of split ring resonators (SRRs) loaded with horizontal strip transmission line is proposed to mitigate the mutual coupling among the MIMO antenna elements. An equivalent circuit model, characterizes the effect of coupling between the array of SRRs and the loaded transmission line, which together reduces the near field coupling between the adjacent antenna elements. The additional horizontal strip at the bottom is utilized to seek the return current path to the ground plane. Polarization and spatial diversity is achieved by utilizing dual slant 450 polarized antenna elements with eight independent channels. All four dual polarized antenna elements are designed to operate with a VSWR of <2 for (2.3-2.4 GHz) Band 40. Dual slant 450 polarization is achieved by utilizing two printed planar bow-tie antennas in orthogonal orientation. Measured and simulated results shows by incorporating periodic array of SRRs loaded with transmission line a considerable mutual coupling reduction of 25 to 50 dB is achieved in E-plane, H-plane, and D-plane over the required band 40. An isolation of 30 dB and an average gain of 7.5 dB is measured for dual slant 450 polarized antenna elements. MIMO performance metrics in terms of envelope correlation coefficient and diversity gain are also investigated.

In this paper, a compact multiple-input-multiple-output (MIMO) antenna is proposed for Ultra-wideband (UWB) applications. The proposed MIMO antenna is comprised by two symmetrically placed half slot antenna elements which one side of the slot is open to the air. Two antenna elements share the same ground plane, and each opening of the half slot gapes to the opposite directions. For covering the entire UWB frequency band, coplanar waveguide-fed structure is utilized in the antenna. This feeding mechanism is prone to generating multiple resonant frequencies and realizing the compact construction. The impedance bandwidth is sensitive to the shape of the radiator. To realize good impedance matching, a fine-tuned ellipse-shaped radiator, which is with semi-major axis 4.8mm and semi-minor axis 3.74 mm, is obtained through numerous optimizations and experiments. The reflection coefficient decreases at the high frequency, because the currents are concentrated on the edge of the slot, and the dielectric loss leads to the loss of energy. To achieve good isolation performance at lower UWB frequency, a fork-shaped slot is etched on the ground, at the center of the bottom. The fork-shaped slot effectively suppresses the currents flowing on the same ground plane, and the mutual coupling of 3–5 GHz reduces from −8 dB to −15 dB below. The overall size of the proposed antenna is only 23 × 18mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The results show that the achieved impedance bandwidth (|S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> |, |S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</inf> | < −10 dB) is from 3 to 12.6 GHz, and the mutual coupling is lower than −15 dB. The antenna also contains stable gain and omni-directional radiation patterns. The proposed compact MIMO antenna with effective UWB performance is competitive for portable UWB MIMO devices.

Implementation of an antenna array on a 5G mobile phone chassis is crucial in ensuring the radio link quality especially at millimeter-waves. However, we generally lack the ability to design antennas under practical operational conditions involving body effects of a mobile user and multipath propagation. Therefore, in this paper, we study gains of three phased antenna array configurations at 28 GHz that can be implemented on a mobile phone chassis, and we compare them to find the most robust configurations. The arrays are formed by placing two sets of 4-element dual-polarized patch antenna arrays, called two modules, at different locations of a mobile phone chassis. The gains we study concern antenna and link gains of the array. Spherical coverage is statistics of realized antenna gain over solid angle, while total array gain is a link gain determined by the power at the receive array output port in relation to the omni-directional pathloss. Our numerical approach to evaluate the gains is based on state-of-the-art methods such as simulations of radiated fields from an antenna element including human body scattering along with ray-optical multipath radio channel simulations. Results show that an array configuration with modules on opposite sides of the mobile phone chassis is clearly the best both at median and outage levels when spherical coverage is concerned. However, according to our evaluation of the total array gain in outdoor and indoor small-cell scenarios, an array of antenna elements on each side of two corners of mobile phone chassis performs equally robust because the array can capture energy from most directions despite nearfield interaction with the human body. The results illustrate the importance of having a link gain metric in addition to an antenna gain metric, to be able to compare and rank array performances.