EM isolation enhancement based on metamaterial concept in antenna array system to support full-duplex application

This study presents a hybrid electromagnetic isolation mechanism in a transceiver array antenna operating at 5.8 GHz. Maximum isolation between transmitting and receiving array antennas, at a very close spacing (3 mm = 0.058 λ 0 ), and minimum mutual coupling between each array elements is achieved without antenna radiation pattern degradation. The achieved separation is equivalent to 44% size reduction compared with conventional half wavelength spacing criterion. Each of the transmitting and receiving array antennas is a four-element linear microstrip patch array antenna. The employed hybrid isolation technique is composed of defected ground structure, to minimise coupling between array elements, and uniplanar electromagnetic bandgap, to minimise the coupling between the transmitting and receiving antennas. The resulting transceiver array antenna system fulfils -35 dB mutual coupling between array elements, and 60 dB isolation between opponent transmitting and receiving array antennas. The proposed design procedures are discussed and analysed using electromagnetic full wave simulations. Results were verified through experimental measurements for reflection coefficient, mutual coupling and radiation characteristics in which a good agreement with simulated results is granted.

This paper presents a printed rectangular slot microstrip antenna array of two elements based on an Electromagnetic Band Gap (EBG) structure. The proposed EBG structure is invented to improve the isolation between the radiating elements for multiple-input multiple-output (MIMO) application. Single and two slotted rectangular microstrip antennas are designed on an FR-4 substrate with a dielectric constant (εr) of 4.3 and loss tangent (tanδ) of 0.025 with thickness of 1.6 mm. The proposed EBG structure is designed as one planar row of 24 slots. The proposed array performance is tested numerically using Computer Simulation Technology Microwave Studio (CSTMW) of Finite Integration Technique (FIT) formulations. The antenna performance in terms of reflection coefficient (S11), isolation coefficient (S21), radiation patterns, boresight gain and Envelope Correlation Coefficient (ECC) are investigated before and after introducing the EBG structure to identify the significant enhancements. The proposed EBG structure is located between the radiating antenna elements to reduce the mutual coupling of the proposed antenna array. The edge to edge separation distance of the proposed antennas is λ0/16, where the λ0 is the free space wavelength at 2.45 GHz. The simulated results show a significant isolation enhancement from –6 dB to –29 dB at the first resonant frequency 2.45 GHz and from –10 dB to –25 dB at the second resonant frequency 5.8 GHz after introducing the EBG structure to the antenna array.

In traditional aerospace telemetry receiving systems, parabolic directional antenna or flat array antenna is generally adopted in the ground telemetry receiving antenna. The antenna array is synthesized into a fixed beam, tracking the target by mechanical scanning. When tracking multi-target is required, it is necessary to deploy multiple ground telemetry antennas to track their respective targets, i.e. one set of antennas tracks one target. Phased arrays antenna is an antenna system and technology developed on the basis of array antenna. Its antenna elements are synthesized into multiple independent beams, which can track one target at the same time, or track each target separately with different beams, so as to achieve the multi-target telemetry and tracking receiving function with a set of phased array antenna. The antenna array element is synthesized into multiple independent beams. This paper mainly discusses an implementation method of multi-target telemetry receiving antenna based on phased arrays technology.

This paper discusses the comparative effect of Electromagnetic Band Gap (EBG) structures on two element Microstrip antenna array. The dielectric substrate used is FR-4 glass epoxy with dielectric constant 4.2 and loss tangent 0.0245. The conventional antenna array is resonating at a frequency of 5.53 GHz with a mutual coupling of -17.83 dB. The first proposed antenna array with square slot EBG structure in the ground plane and fractal patch EBG structure on the surface produces a mutual coupling of -50.21 dB and a gain of 8.78 dB at 5.53 GHz. The second proposed antenna array with star slot EBG structure in the ground plane and diamond patch EBG structure on the surface produces a mutual coupling of -51.63 dB and a gain of 7.20 dB at 5.53 GHz. Both the proposed antenna arrays are producing appreciable decrease in back lobe radiation. The antenna arrays are designed using Mentor Graphics IE3D software and measured are obtained using vector network analyzer.

The article will present the array antenna system for Monopulse tracking application. The Antenna includes 3 parts: monopulse comparator, unequal power divider, and antenna array. The monopulse comparator and unequal power divider are designed by microstrip line on PCB. Antenna array consists of 244 Vivaldi elements. Conducted simulation of the antenna system and obtained the following results: The bandwidth of the antenna system is greater than 10% with Voltage Standing Wave Ratio smaller than 1.6 (VSWR ≤1.6); Realized gain of the sum beam (radiation pattern) at the central frequency reaches 26.2 dBi; Sidelobe level of sum beam is less than -20dB in the whole frequency range; The peak and null of two difference beams are smaller than 20dB. With the results obtained, the Antenna Monopulse system is mentioned as completely suitable for use for tracking applications and arrangement in narrow space locations with compact size.

One of important parameters in array antenna is radiation characteristic which can be satisfied by implementing several design techniques. In this paper, by utilizing differentially proximity-coupled feeding technique, a circular ring-shaped array antenna is designed with improved radiation pattern characteristics. The proposed array antenna consists of 20 circular ring-shaped antenna elements arranged in 4 $\times$ 5 array. Differentially proximity-coupled feeding technique applied for each antenna element is aimed to have symmetrical radiation pattern. The array antenna which is designed to work at the frequency of 1.275 GHz for L-band frequency application is implemented using two layers of FR4 epoxy dielectric substrate with the total dimension of 199.3 mm $\times$ 189.5 mm. The characterization result shows that the proposed array antenna has good impedance matching with the reflection coefficient $(S_{11})$ of −21.65 dB and −10 dB impedance bandwidth of 80 MHz (1.21 GHz to 1.29 GHz). Meanwhile, a symmetrical radiation pattern at $E-$ plane is achieved with the half power beamwidth (HPBW) of 43°.

In this paper, a high-gain L-probe antenna array, which also has a broadside radiation pattern, is presented. To demonstrate the design idea, three L probes are placed along the vertex of a V-shaped ground to form a 3×1 antenna array. In this structure, the ground plates also act as a corner reflector. The proposed antenna array is simple and can be easily constructed by only using wires and metal plates. In this paper, the input impedance, antenna gain, and radiation patterns of the proposed antenna are studied.

PurposeThis paper aims to present the design of a compact vertically polarized four-element UWB antenna suitable for MIMO communications.Design/methodology/approachThe unit cell antenna is constructed using a square ring radiator excited through a stepped impedance feed. The proposed antenna covers the Ultra-wideband (UWB) spectrum ranging from 2.2 to 12.3 GHz. The isolation between the unit cell antennas in the array is enhanced using a simple microstrip line resonator. The decoupling element is connected to the ground through a via.FindingsThe proposed scheme offers at least 16 dB improvement in the port-to-port coupling. Furthermore, the four-element antenna array is constructed using a specific interlocking scheme. The proposed antenna array’s Multiple Input Multiple Output (MIMO) performance metrics are analyzed.Originality/valueBy suitably selecting the excitation port, directional radiation patterns can be realized. The combined radiation pattern covers 360 degrees. A prototype antenna array is fabricated, and the simulation results are verified using real-time experiments. The proposed antenna is a suitable candidate for shark fin housing in automotive communications.

This communication presents a 60-GHz wideband circularly polarized (CP) U-slot patch antenna array of 4 × 4 elements on low temperature cofired ceramic (LTCC). A CP U-slot patch antenna is used as the array element to enhance the impedance bandwidth and a stripline sequential rotation feeding scheme is applied to achieve wide axial ratio (AR) bandwidth. Meanwhile, a grounded coplanar waveguide (GCPW) to stripline transition is designed for probe station measurement. The fabricated antenna array has a dimension of 14 ×16 × 1.1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The simulated and measured impedance bandwidths, AR bandwidths, and radiation patterns are investigated and compared. Measured results show that the proposed antenna array has a wide impedance bandwidth from 50.5 GHz to 67 GHz for |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB, and a wide AR bandwidth from 54 GHz to 65.5 GHz for AR <; 3 dB. In addition, it exhibits a peak gain of 16 dBi and a beam-shaped pattern with 3-dB beam width of 20 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> . Moreover, its AR keeps below 3 dB within the 3-dB beam width.

In this paper, a dual-polarized microstrip array antenna with orthogonal feed circuit is proposed. The proposed microstrip array antenna consists of a single substrate layer. The proposed array antenna has microstrip antenna elements, microstrip lines, air-bridges and cross slot lines. For dual polarization, an orthogonal feed circuit uses the Both-Sided MIC Technology including air-bridges. The Both-Sided MIC Technology is one of the useful MIC technologies for realizing a simple feed circuit. The air-bridges are often used for MMICs because it is possible to reduce the circuit complexity. The characteristics of proposed array antenna are investigated by both the simulation and the experiment. Consequently, it is confirmed that the proposed array antenna with the orthogonal feed circuit has dual polarization performance with very simple structure. The proposed array antenna will be a basic technology to realize high performance and attractive multifunction antennas.

Auto-pointing and angular super-resolution properties of the radiation patterns generated by an electrically compact retrodirective monopole antenna array are demonstrated experimentally for the first time. The operation of electrically compact (element spacings less than one-fifth of the radiation wavelength) retrodirective antenna arrays that were theoretically considered in our previous work is confirmed by measurement. Particularly, it is shown that the direction-of-arrival information carried by an incident electromagnetic wave can be encoded into the evanescent near field of an electrically small resonant antenna array with a spatial rate higher than the spatial oscillation rate of the incident field in free space. This observation is supported by the near-field measurements, demonstrating that the magnitude of the scattered (evanescent) field in the array environment can exceed the magnitude of the incident field in free space by at least 6 dB. Retrodirective array antenna matching and the feasibility of a frequency-division full-duplex communication link based on the proposed antenna arrays are also discussed.

The use of bandwidth for mobile and cellular networks has been increasing at an unprecedented rate, with applications in emergent areas such as smart vehicles and civil infrastructure, telemedicine, and remote education. The predicted increase of mobile network utilisation requires a high data rate capacity to transfer information through the network. The current limited capacity of the fourth generation (4G) mobile network is not expected to satisfy the predicted high data demand by 2020. To meet this requirement, a new fifth generation (5G) mobile network has been proposed. In order to reach the high capacity demands, the 5G requires a wide frequency bandwidth, which is not available in the sub-3 GHz frequency spectrum. Therefore, many international organisations have assigned the millimetre-wave band (mm-Wave), which includes 24, 28, 37, 39, and 60 GHz, as a frequency band for 5G. Using mm-Wave raises many challenges such as an increase in the path loss, radiation field absorbed by the human body, signal polarisation misalignment, and MIMO antenna footprint inside the mobile handset. Therefore, designing beam-steering, reconfigurable circular polarization, and compact MIMO antenna systems for 5G applications is important to cope with these challenges. Although there are some antenna systems were reported recently for mm-Wave 5G, they had limited steering angles, one polarization types or bulky antenna size. This thesis aims to solve the current challenges mentioned above by developing mm-Wave 5G antenna systems and in doing so makes three main contributions to the field of mm-Wave 5G antenna systems.As the path loss and radiated fields absorbed by surface layers of the human body increase at mm-Wave, emphasis is given into the development of the beam-steering antenna system, which is the first contribution of this thesis. The beam-steering technique aims at reducing the effects of electromagnetic field exposure on the human head, as well as maintain a consistent connection between the handset and the base station. A novel compact three-dimensional (3-D) beam-steering system of mobile handsets at 28GHz is proposed. It consists of dipole antenna arrays, power dividers and digital phase shifters. Nevertheless, a novel technique of connecting p-i-n diodes to build a phase shifter is proposed for better performance. The proposed design has the ability to steer the beam in a wide angle in 3-D. it relies on using both sides of a printed circuit board for a two-dimensional antenna array. Moreover, to further improve the performance of the beam-steering system, a tunable power divider for mm-Wave 5G is presented. It is used to tune the feeding amplitude of the beam-steering antenna array, and thus reduces the side-lobe level (SLL) of the antenna radiation pattern.n nThe second contribution is the development of two reconfigurable circular polarisation (CP) structures for 5G applications at mm-Wave. CP is an effective technique to mitigate signal polarisation misalignment, phase deviation and multipath effect problems. Electrical reconfigurable methods are used to switch the CP type by using p-i-n diodes. Firstly, an open-ended stub concept with a simple feed circuit is used to build a novel reconfigurable CP patch antenna. Then the same concept is developed to build a reconfigurable CP antenna array system using branch-line couplers, power divider, and 4 p-i-n diodes. The open-ended stub concept is found to be efficient in both designs by reducing the complexity and the number of the p-i-n diode switches compared to the reported existing CP antenna systems in the literature.MIMO is a major technology of 4G mobile antenna system and also has disruptive potential for mm-Wave 5G. Therefore, the third contribution is the development of new design approaches to integrate the current 4G with futurist 5G MIMO antenna systems. Integrating these two technologies in one structure leads to a reduction of the total MIMO antenna footprint significantly within handsets, where the available space is limited. To that end, two novel 5G/4G MIMO antenna systems are built. First, 5G/4G MIMO antenna system is proposed by using one structure; and it covers multiband mm-Wave spectrums (28, 37 and 39) GHz for 5G as well as sub 3 GHz for 4G.n Moreover, to further improve the gain especially at mm-Wave band, an antenna array structure is deployed to build another 5G/4G MIMO antenna system. This design integrates 5G and 4G operations into a single structure; and covers a wideband 23-29 GHz for 5G and frequency-tuning 2.05-2.70 GHz for 4G.The developed antenna systems reported in this thesis positively contribute to the antenna design domain and are expected to encourage safety, compactness, reliability, and a multiband antenna system for the mm-Wave 5G industry in near future.n

This work proposes a Yagi-Uda array with fan-like driver for millimeter-wave application. The proposed antenna array is built on a low-cost and low-loss multilayer organic substrate for flip chip ball grid array (FCBGA) package. The package size is 16 × 8 × 0.44 mm3. The proposed four-element antenna array results in a peak gain of 12 – 14.5 dBi at operating frequency band. The proposed antenna achieves both broadband and high gain characteristics for millimeter-wave application. The proposed antenna array is also used to develop a low-cost 60-GHz switched-beam antenna array with butler matrix network. This work provides a cost-effective approach to implement a switched-beam antenna array for fifth-generation mobile communications (5G), IEEE 802.11ad, such as smart phone, laptops, and wireless router.

This study proposed a Controlled Reception Pattern Antenna (CRPA) array for digital beam forming in Global Navigation Satellite System (GNSS) applications. The proposed array antenna was designed to receive signals in both the GPS L1 (1.57542 GHz) and GLONASS L1 (1.602 GHz) bands. To accommodate a specific platform, it featured eight antenna elements arranged in a circular pattern on a 9-inch circular plate. The array elements were fed using a low-temperature co-fired ceramic (LTCC) hybrid coupler that provided a 90° phase difference and two indirectly fed probes to achieve circular polarization. The proposed antenna was optimized and fabricated using three-dimensional electromagnetic (3D EM) simulation tools, and its performance was evaluated through measurements conducted using a network analyzer and in an anechoic chamber. The measured voltage standing wave ratio (VSWR) of the antenna array averaged below 1.7:1, and the average gain exceeded 0 dBic. The antenna was also tested under real-world outdoor conditions using a commercial satellite receiver, successfully verifying its ability to reliably receive satellite signals within the designed frequency bands.

Radars remain the only all–weather location systems, which is especially important in difficult conditions of their use. Antenna array technologies remain critical for the development of dynamic areas of technology and, first of all, UAVs location systems. The development of location systems and antenna arrays for UAVs has been going on for a long time. Radars and antenna arrays installed on medium– and large–class UAVs differ little from airplane and helicopter systems. Among UAVs, the maximum number of UAVs used are UAVs of minimal size, weight and cost. Due to their high maneuverability, minimal visibility and a large number of tasks to be solved. Therefore, radars are subject to minimum size, weight, dimensions and consumption requirements at maximum range. The widespread use of small UAVs has led to the fact that their radars and antenna arrays are on a par with automotive ones, when the possibilities for their placement are significantly limited, even more so than in cars. For the latter, the problem of miniaturization appeared earlier, but not as severely as in UAVs. Antenna arrays are subject to requirements for minimizing dimensions, weight and consumption. Nanotechnology provides this. It's safe to say that the time has come for large–scale solutions to complex problems in antenna systems. Depending on the type of a UAV, it is possible to use a number of methods for constructing antenna arrays: known and proven – linear and fractal; the most modern – metastructures; widely used – tiled; new: flexible and three–dimensional printed; a combination of several methods. Currently, the most attractive areas for the development of antenna arrays for UAVs are: scaling – growing a large number of similar structures to create large apertures; spacing antenna arrays across the surface of the carrier for viewing both forward, sideways and backward, as well as down and up. The development of silicon tiled antenna arrays has led to the realization of very high operating frequencies (90–100 GHz) on the most affordable process technologies (130–180 nm), and the antenna array is fabricated as a chip. The optimal option for constructing antenna arrays is to ensure the reception, conversion and preprocessing of input signals directly in the antenna system in real time, unloading the radar for solving problems that require powerful processing. Post–processing allows you to obtain a more accurate solution to the problem. The combination of pre–processing and post–processing, supported by advanced software and powerful artificial intelligence, expands the capabilities and improves the parameters of the location system. It is important that artificial intelligence ensures the autonomous movement of a UAV, although its use requires large consumption and memory resources. The integrated location system absorbed for the most part the capabilities of a large stationary radar. At the same time, minimum dimensions, weight and consumption are ensured to solve the necessary modern problems. Several radars with their own antenna arrays can be installed on a UAV, which operate in the internal network, complementing each other.