This letter proposes a new design of millimeter-wave (mm-Wave) array antenna package with beam steering characteristic for the fifth-generation (5G) mobile applications. In order to achieve a broad ...three-dimensional scanning coverage of the space with high-gain beams, three identical subarrays of patch antennas have been compactly arranged along the edge region of the mobile phone printed circuit board (PCB) to form the antenna package. By switching the feeding to one of the subarrays, the desired direction of coverage can be achieved. The proposed design has >10-dB gain in the upper spherical space, good directivity, and efficiency, which is suitable for 5G mobile communications. In addition, the impact of the user's hand on the antenna performance has been investigated.
In this paper, a recently conducted measurement campaign for unmanned-aerial-vehicle channels is introduced. The downlink signals of an in-service long-time-evolution network, which is deployed in a ...suburban scenario were acquired. Five horizontal and five vertical flight routes were considered. The channel impulse responses (CIRs) are extracted from the received data by exploiting the cell-specific signals, and the underlying physical propagation mechanisms are interpreted by exploiting the propagation graph modeling approach. Based on the CIRs, the parameters of multipath components are estimated by using a high-resolution algorithm derived according to the space-alternating generalized expectation-maximization (SAGE) principle. Based on the SAGE results, channel characteristics including the path loss, shadow fading, fast fading, delay spread, and Doppler frequency spread are thoroughly investigated for different heights and horizontal distances, which constitute a stochastic model.
A concept of decoupling ground is introduced in this paper to enhance the isolation of massive MIMO antenna arrays. For an array, mutual coupling between array elements can be achieved by the ...free-space coupling and the coupling currents flowing on the ground plane shared by elements. The isolation in this paper is improved by adjusting the shape of the ground plane under each element to make the mutual coupling from the free space and the ground plane out of phase. In this way, low mutual coupling is realized. As the first example, a single-polarization linear array with eight elements is designed, simulated, and measured to verify the concept as well as the simulation accuracy. The measurements align very well with the simulations. Another two examples of dual-polarization 2×2 and 4×4 square arrays are also given and simulated to demonstrate the effectiveness of the proposed technique. In all of these examples, the isolation can efficiently be enhanced with the DG for all the co-polarization and cross-polarization coupling paths of the massive MIMO elements. Compared with the previous literature, the arrays with the DG method can achieve either much better isolation or a much lower profile while keeping the other performance comparable.
In this paper, a mobile terminal phased array at 28 GHz with different scan angles is compared with a switch diversity antenna array at 28 GHz in the case of antenna beams pointing at the user's ...body. In the switch diversity antenna array, there is only one element out of eight operating each time. The paper is carried out in data mode with a standing user, which includes both body blockage and user hand effects. The metrics of coverage efficiency, antenna shadowing power ratio, and isotropic antenna shadowing power ratio are utilized in the investigation. It is found that the scan angle of a phased array higher than 90° is not necessary for this scenario, because the user body will contribute to the total radiation at large angles by scattering the radiated energy around the body. For the linear phased antenna arrays on the edge of the mobile device ground plane, it can be concluded that in order to achieve the highest coverage efficiency and lowest user shadowing it is more beneficial to use a phased array instead of a switch diversity array. However, if the losses of the phase shifters and the feeding network from the phased array are higher than 5 dB, the switch array can be used, which will also decrease the complexity of a system.
Millimeter-wave (mmWave) frequency bands are promising candidate spectrum for the fifth-generation (5G) mobile communication system, but it requires high directional antenna systems to be applied to ...the base station and the user equipment (UE) for compensating the high path loss. Due to the randomness of mobile wireless channels, antenna systems in a mobile UE must own a large spherical coverage, which raises new challenges for the performance characterization of 5G mmWave UEs. In the latest specification of the Third-Generation Partnership Project (3GPP), the requirement on UE's spherical coverage in mmWave frequencies is defined, which is evaluated with the cumulative distribution function of the effective isotropic radiated power. In this paper, the spherical coverage of mmWave UEs is characterized based on the specification of 3GPP, where the impact of device integration, antenna topologies, and user body blockage on the spherical coverage of UE will be analyzed with simulation and measurement results.
A dual-band structure-reused antenna with quasi-elliptic bandpass feature is proposed in this communication. The antenna consists of a cavity-backed slot array working at <inline-formula> <tex-math ...notation="LaTeX">K </tex-math></inline-formula>-band (24.2-26.1 GHz) and a frequency selective surface (FSS), which is transparent to the <inline-formula> <tex-math notation="LaTeX">K </tex-math></inline-formula>-band radiation and also reused as a radiator at <inline-formula> <tex-math notation="LaTeX">S </tex-math></inline-formula>-band (2.5-2.7 GHz). The FSS unit cells are designed based on the cross-slot structure. By introducing asymmetric boundaries to each unit cell, the FSS obtains high-frequency selectivity with two transmission zeros located on each side of the passband. The proposed antenna is fabricated and measured. The measurements have a good matching with the simulations.
A compact beam-steerable antenna array is proposed for 28 GHz mobile terminals. The proposed array consists of one active element and two passive parasitic elements. Two switches are utilized in the ...design instead of phase shifters. Each parasitic element can be terminated with short-circuited transmission lines of different lengths via one switch. By controlling the two switches, different reactive impedance is loaded on two parasitic elements. The radiation pattern of the active element can be scattered into different directions by two parasitic elements. The switching loss is studied, where two switches with 2.8 dB loss cause less than 1.82 dB loss for the whole array. The small array locations on the chassis are also investigated. The designed array is smaller than 0.81 wavelength, and covers the band of 28-29 GHz with the scan angle ≥±90°. By placing two arrays on each long chassis edge, 360° beam steering can be realized. Surface currents on the chassis are efficiently excited to achieve high gain with the small array. Measurements are carried out and align well with simulations. In practical applications, several small arrays can be implemented on the metal back cover and around a cellphone to combat users' mobility.
This paper introduces a planar switchable 3-D-coverage phased array for 28-GHz mobile terminal applications. In order to realize 3-D-coverage beam scan with a simple planar array, chassis surface ...waves are efficiently excited and controlled by three identical slot subarrays. Three subarrays switch their beams to three distinct regions. Each subarray works as a phased array to steer the beam within each region. Large coverage efficiency is achieved. (e.g., 80% of the space sphere has the realized gain of over 8 dBi.) The proposed antenna covers a bandwidth of over 2 GHz in the band of 28 GHz. User effects on the switchable array are also studied in both data mode and talk mode (voice) at 28 GHz. In talk mode, good directivity and beam switching can be realized by placing the switchable array at the top of the chassis (close to the index finger). And the user shadowing can be significantly reduced by placing it at the bottom of the chassis (close to the palm). In data mode, the switchable array, mounted at the top, achieves less body loss and larger coverage than at the bottom. The proposed antenna is fabricated and measured. The array at the top in talk mode is measured with a real human. The measurements align well with simulations.
In this paper, a dual-band antenna at 4.5 GHz and 25 GHz is presented. The antenna is a low-frequency phased patch antenna array combined with a high-frequency transmitarray with a fixed beam. The ...low-frequency patch antenna array and the high-frequency transmitarray feed share the same aperture area. The high-frequency transmitarray surface only uses a single substrate layer and is electrically transparent to the low-frequency phased array with beamforming. The antenna is measured to achieve an impedance bandwidth of 350 MHz and 3 GHz, and a gain of 15.4 dBi and 23.5 dBi, at S- and K-band respectively. With an impressive frequency-ratio of 5.55 and an aperture area of only 12x12cm the antenna achieves an aperture efficiency of 66% and 15% in the two bands respectively. Additionally, the low-frequency beamforming capabilities (with the existence of transmitarray surface) are measured and the antenna is shown to have a 60-degree scanning range with only a 0.22 dB gain drop-off.
Direction-of-arrival (DOA) estimation plays a vital role in the field of array signal processing. However, the need for heavy computing tasks in most traditional DOA algorithms, e.g., multiple signal ...classification (MUSIC), makes their engineering practicality significantly compromised in satellite communication systems. The neuroevolution of augmenting topologies (NEAT) can quickly search for appropriate topologies and weights of neural network functions, but its computational complexity is still too high for satellite systems. This paper proposes a modified NEAT architecture featuring a recurrent structure (RNEAT) that only needs a small number of phase components of the received signal covariance matrix as inputs to reduce the complexity and simplify the neural network architecture. The proposed RNEAT incorporated with multiple signal classification (RNEAT-MUSIC) features low complexity to achieve high resolution and low complexity simultaneously. Validation has been done by applying the proposed method in a two-dimensional direction of arrival estimation (2D-DOA) problem. Results show that the proposed RNEAT-MUSIC efficiently restricts the scanning region before forwarding the covariance matrix to the MUSIC stage. Consequently, the computational workload is reduced by 3/4 compared with the traditional 2D-MUSIC algorithm while maintaining satisfactory DOA resolution.
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