A 4-port wideband Multiple-Input Multiple-Output (MIMO) antenna operating in the frequency band from 24.8 GHz to 27.6 GHz dedicated to 5G application is proposed in this manuscript. The MIMO antenna is implemented on a 23.75 × 42.5 × 0.508 mm3 Roger/Druoid 5880 substrate with relative dielectric constant εr = 2.2 and loss tangent 0.0009. Firstly, the design starts with a simulation and optimization of a single element antenna based on Minkowski fractal shape as Defected Ground Structures (DGSs) using CST Studio Suite. The single proposed element shows a 7 dBi gain and antenna efficiency of 85% at the operating frequency band. Secondly, to design a MIMO antenna with good isolation, three different configurations are used, and overall MIMO performances such as low Envelope Correlation Coefficient (ECC), high Diversity gain (DG), and low Channel Capacity Loss (CCL) are calculated and analyzed. Finally, fabrication and measurement are conducted to validate the concept for single and 2-port MIMO antenna performance.
An 8-element/8-port antenna with four resonating dual-polarized slot radiator elements for sub-6 GHz 5G multiple-input multiple-output (MIMO) applications is proposed in this paper. The proposed MIMO design comprises four annular slot radiators with dual-polarized characteristic and has rectangular micro-strip line feeds. The designed elements operate in the frequency bands 2.73-3.12 GHz and 4.33-4.68 GHz providing an acceptable characteristic for dual-polarizations. The isolation improvement and reduction in mutual coupling factor are achieved by using split ring resonator (SRR) structures on the top layer along the slot radiator. The proposed design has a -10dB wide impedance bandwidth in both bands, considerable realized peak gain around 4 dBi, and better efficiencies around 80\% with ECC < 0.004 which has enhanced the performance of the MIMO array in terms of diversity. The antenna is fabricated, characterized, and it is shown that the measured results are in good agreement with the simulated ones. The proposed MIMO design has been analyzed for SAR functions and the radiation coverage in the vicinity of the user human head. The SAR values studied are found to be less than `2' which is quite desirable. All the features achieved in the proposed MIMO design suggest it to be suitable for 5G mobile terminal applications.
In this paper, a Rectangular Monopole Antenna (RMPA) with offset microstrip feed is presented. The structure is fabricated on an FR4 substrate with a dimension of 28 x 32 x 1.6 mm3. The proposed structure achieves multiband operation by engraving 2 Complementary Split Ring Resonators (CSRRs) and a C-Shaped slot. Also, 2 Split Ring Resonators (SRRs) are printed on the adjacent sides of the radiating element. The parametric analysis is used to determine the optimum position of the feed and other critical parameters. The proposed structure operates at 2.25 GHz, 3.86 GHz, 4.60 GHz, 5.64 GHz, 5.86 GHz, 6.94 GHz,7.48 GHz, and 9.47 GHz. The permeability of the SRR and permittivity of the CSRR are extracted and presented. The proposed antenna is fabricated and measured. The measured results of S11, radiation pattern, and gain are on par with the simulated results. The proposed antenna's simulated surface current and efficiency are also presented to validate the performance. Simple structure, stable radiation patten, multiband operation, reasonable gain, and efficiency are the significant features of the proposed RMPA.
This paper presents a new design concept of dual bandpass filter. Based on the strong coupling between two resonators, a dual 1-pole band-pass filter is designed and is used as the basic building block. By providing appropriate weak coupling between these building blocks, a higher-order dual bandpass filter can be realized. In addition, these building blocks can be stacked vertically and/or horizontally to construct a compact filter. In this way, by using 3D full wave EM and circuit co-simulation, the simulation time required in the design stage can be reduced. In addition, it also provides a way to post-tune each building block individually and further reduces the time required in prototype post tuning process. For demonstration, an L-band dual 4-pole bandpass filter is designed with passband frequencies of 1.23 GHz~1.255 GHz and 1.55 GHz~1.6 GHz. In order to reduce the size of the filter and obtain a wide stopband bandwidth, a suitable evanescent mode cavity is used to realize the resonant structure. The measurement result shows that the insertion losses of the low passband and high passband are 1.03 dB~2.00 dB and 1.02 dB~1.75 dB, respectively; the return loss of both passbands is better than 15 dB. Furthermore, up to 5 GHz (> 3fo, where fo is at 1.39 GHz), the stopband rejection level is better than 80 dB.
In this work, a novel 4 element Multi-Input Multi-Output (MIMO) antenna is reported. The proposed antenna has a size of 50x50x1.6 mm3 is printed on the FR-4 substrate having dielectric constant εr = 4.4 and loss tangent (tan δ = 0.02). The four antenna elements are positioned in each corner of the PCB board in an orthogonal manner such that they can provide better isolation between antenna elements. The proposed MIMO antenna is designed to operate in frequency bands of 2.25 GHz to 2.4 GHz and 4.7 GHz to 6.3 GHz. The lower band ranges from 2.25 GHz to 2.4 GHz and covers 2.3 GHz WiBro applications while the upper band ranging from 4.7 GHz to 6.3 GHz is useful for Hiper LAN and Wi-MAX applications. The proposed antenna acquires return loss less than -10 dB and isolated by more than 16 dB throughout the dual operating bands. The structure exhibits stable gain and radiation patterns. Various diversity performance metrics including envelope correlation coefficient (ECC), diversity gain (DG), and mean effective gain (MEG) are evaluated and are within acceptable limits.
A frequency reconfigurable microstrip patch antenna with two asymmetric L-slots is proposed in this article. Two RF pin diodes inserted on the asymmetric L-slots are used to switch the operating frequency over the C band. Design and optimization of different physical parameters of the antenna viz. slot dimensions, feed location, notch size and pin diode positions are carried out using High Frequency Structure Simulator Version 13.0. The design is implemented on an FR4 substrate (εr = 4.4) of dimension (35×40×1.6) mm3. DC bias circuitry for RF PIN diode activation is also integrated with the antenna. Switching combinations of two PIN diodes offer four reconfiguration modes of operation at 4.75, 5.05, 5.11 and 5.18 GHz. In all the states, the -10 dB bandwidth shows minimal changes with average variations of 15.8% with respect to the state when both PIN diodes are OFF. The gains of the antenna for different modes of operation are found almost stable with an average of 6.64 dBi.
A problem of electromagnetic waves radiation diffracted at a narrow rectilinear arbitrarily oriented slot cut in an end wall of a semi-infinite rectangular waveguide is solved by an asymptotic averaging method. The slot radiates into a half-space over an infinite perfectly conducting plane. An influence of slot inclination angle upon energy and spatial characteristics is numerically studied. Theoretical results are compared with experimental data. A numerical-analytical problem of a narrow rectilinear slot radiating into the space above an infinite impedance plane is also presented. The asymptotic solution for the slot magnetic current was obtained by a generalized method of induced magnetomotive forces (MMF) by using Green's functions of a space above the impedance plane. The effect of the plane with impedance coating on the slot is reduced taking into account an additional term to the slot external conductivity, for which the expressions were obtained in an analytical form.
Over the past few years, the continuous evolution of embedded electronic systems has increased electromagnetic interferences problems. It has also generated a new design constraint on electromagnetic compatibility. Hence, predicting the electromagnetic field behavior in the vicinity of the electronic components and systems becomes a priority to avoid the potential for unwanted coupling occurrence, as well as to ensure the electromagnetic compatibility compliance for those components and systems which are embedded in a confined space. As a result, the designers of electronics' equipment are extremely interested in radiated emission models. This paper reports a comparative study in which two different methods will be applied: the equivalent source method and plane wave spectrum method. These two methods will be used to predict the magnetic field behavior in the vicinity of a microstrip patch antenna. The latter works in ISM band for Wi-Fi and Bluetooth applications. The two applied models are constructed from the tangential magnetic fields cartographies of the antenna obtained from HFSS® at 3.5 mm and validated by comparing the HFSS® results with those of the models at a higher elevation. Furthermore, the relative error between the simulated field of the antenna and those of the equivalent source model according to the dipoles number is presented to determine the minimum number of dipoles that allow users to obtain the results with better accuracy. Subsequently, the relative error as function of different elevations along the z axis together with the two methods comparison results is presented.
We present the design, optimization, and analyses of efficient couplers to construct nano-optical transmission systems involving nanowires. The couplers consist of optimized arrangements of nanocubes and are integrated into critical locations, such as nanowire inputs, corners, and junctions, to improve electromagnetic transmission in accordance with design purposes. Optimization and numerical analyses are performed by employing an efficient simulation environment based on a full-wave solver and genetic algorithms. Using the designed couplers, we obtain various configurations that enable efficient transmission and distribution of input powers to multiple outputs. With their favorable properties, the designed couplers and constructed systems can be further used to build larger nanowire networks.
A compact broadband circularly-polarized (CP) patch antenna with a wide 3-dB axial-ratio (AR) beamwidth is proposed for universal ultra-high-frequency (UHF) radio frequency identification (RFID) applications. The proposed antenna consists of four triangular radiation patches and a compact feed network. Each of the radiation patches is grounded by shorting pins for 3-dB AR beamwidth enhancement and patch miniaturization. The feed network having a miniaturized hybrid coupler and two trans-directional couplers is proposed for good circular polarization. Measured results show that the -10-dB impedance bandwidth of the antenna is 18.4% (820-986 MHz); the 2.5-dB AR bandwidth is 32.8% (700-975 MHz); and the gain is 5.12 dBic. The measured 3-dB AR beamwidths for the planes of phi = 0° and phi = 45° are 177° and 190°, respectively. The overall antenna size is 0.408λ0 × 0.408λ0 × 0.053λ0 at 900 MHz.