Mothana L. Attiah

The side lobe effects cause the wastage of energy in antenna arrays. In this work, two types of electromagnetic band‐gaps (EBGs) are used to diminish the side lobes in 2 × 2 Patch Antenna Array at 6 GHz through mushroom‐like EBG and triple side slotted (TSS) EBG (TSSEBG). The proposed EBGs are placed on the top surface of the antenna array to eliminate undesired surface currents. The connecting vias in TSSEBG compared with the mushroom‐like EBG structure is decreased from 392 to 92. Accordingly, an easy way in fabrication is guaranteed. The TSSEBG provided triple band gaps of frequencies compared with the structure of mushroom‐like EBG that only had one. The TSSEBG is placed in a flexible structure, which is suitable for antenna applications. The compact EBG and TSSEBG antenna arrays respectively demonstrate 13.77 and 14.68 dB gain, 14.2 and 15.3 dBi directivity, −24 and − 28.5 dB side lobe, and 90.5% and 87% efficiency at the operating frequency of 6 GHz.

This study presents a novel half-width microstrip leaky wave antenna (HW-MLWA) that can electronically control its beam at a fixed frequency by using a double-gaps capacitor with diodes, resulting in good impedance matching with small variation gain while scanning. The elementary building blocks of this antenna are periodic HW-MLWA and seven control unit cells (CUCs). A reconfigurable CUC is created by combining two triangle patches as double-gaps capacitor with two diodes as switches to connect the patches with the ground plane. A gap capacitor in each patch cell is independently disconnected or connected by using a PIN diode switch. The reactance profile at the free edge of the microstrip is modified when the state of the patch cell changes, which in turn, shifts the main beam direction. A single-pole double-throw switch is used to achieve backward-to-forward beam scanning at a certain frequency. An HW-MLWA is designed, fabricated, and validated. The proposed antenna prototype can scan the main beam forward between +28° and +67° and backward between -27° and -66° at 4.2 GHz. The measured peak gain of the antenna is 11.12 dBi at 4.2 GHz, the gain variation is 1.3 dB while scanning.

The spectrum sharing approach (SSA) has emerged as a cost-efficient solution for the enhancement of spectrum utilization to meet the stringent requirements of 5G systems. However, the realization of SSA in 5G mmWave cellular networks from technical and regulatory perspectives could be challenging. Therefore, in this paper, an analytical framework involving a flexible hybrid mmWave SSA is presented to assess the effectiveness of SSA and investigate its influence on network functionality in terms of independence and fairness among operators. Two mmWave frequencies (28 GHz and 73 GHz) are used with different spectrum bandwidths. Various access models have been presented for adoption by four independent mobile network operators that incorporate three types of spectrum allocation (exclusive, semipooled, and fully pooled access). Furthermore, an adaptive multi-state mmWave cell selection scheme is proposed to associate typical users with the tagged mmWave base stations that provide a great signal-to-interference plus noise ratio, thereby maintaining reliable connections and enriching user experience. Numerical results show that the proposed strategy achieves considerable improvement in terms of fairness and independence among operators, which paves the way for further research activities that would provide better insight and encourage mobile network operators to rely on SSA.

In order to suppress the surface waves excitation that are caused by thick substrate in a patch antenna, a mushroom-like EBG (Electromagnetic Band Gap) structure is used. Such structures enhance its characteristics of gain, directivity, bandwidth and efficiency. Firstly, we determined frequency band gap characteristics of mushroom like EBG unit cell value by using CST software with 3mm (0.06λo) for covering 6 GHz. The periodic arrangement of such mushroom-like EBG structures was not limited by any interconnecting microstrip lines. Four columns of EBGs shifted inwards to antenna edges by 0.3mm (0.06λo) or a gap of its design around the patch from the left and right sides. Different configurations were also examined in order to get the better improvement in antenna performance. The final design of this mushroom-like shifted periodic structure shows an effective increase in the directivity by 77%, gain by 108%, bandwidth by 29% and the efficiency by 20% for the antenna. This structure has diversified application possibility for wireless and satellite communications.

Millimeter wave bands have been introduced as one of the most promising solutions to alleviate the spectrum secrecy in the upcoming future cellular technology (5G) due the enormous amount of raw bandwidth available in these bands. However, the inherent propagation characteristics of mmWave frequencies could impose new challenges i.e. higher path loss, atmospheric absorption, and rain attenuation which in turn increase the outage probability and hence, degrading the overall system performance. Therefore, in this paper, a novel flexible scheme is proposed namely Adaptive Multi-State MmWave Cell Selection (AMSMC-S) through adopting three classes of mmWave base stations, able to operate at various mmWave carrier frequencies (73, 38 and 28 GHz). Two mmWave cellular Grid-Based cell deployment scenarios have been implemented with two inter-site-distances 200 m and 300 m, corresponding to target area of (2.1 km2) and (2.2 km2). The maximum SINR value at the user equipment (UE) is taken in to consideration to enrich the mobile user experience. Numerical results show an improvement of overall system performance, where the outage probability reduced significantly to zero while maintaining an acceptable performance of the 5G systems with approximately more than 50% of the mobile stations with more than 1Gbps data rate.

In this paper, a novel design for single-layer half width microstrip leakywave antenna (HW-MLWA) is demonstrated. This model can be digitally control its radiation pattern at operation frequency and uses only two values of the bias voltage, with better impedance matching and insignificant gain variation. The scanning and controlling the radiation pattern of leaky-wave antennas (LWA) in steps at an operation frequency, by using switches PIN diodes, is investigated and a novel HW-MLWA is introduced. A control cell reconfigurable, that can be switched between two states, is the basic element of the antenna. The periodic LWA is molded by identical control cells where as a control radiation pattern is developed by combining numerous reconfigurable control cells. A gap capacitor is independently connected or disconnected in every unit cell by using a PIN diode switch to achieve fixedfrequency control radiation pattern scanning. The profile reactance at the free edge of (HW-MLWA) and thus the main lobe direction is altered by changing the states of the control cell. The antenna presented in this paper, can scan main beam between 18o to 44o at fixed frequency of 4.2 GHz with measured peak gain of 12.29 dBi.

Recent works have brought down the curtain on the best solutions to meet the requirements of the future cellular communication (5G) which so-called Millimeter-wave (mmWave) frequencies that are expected to offer an excellent opportunity to increase data capacity and channel capacity due to the enormous amount of available raw bandwidth. However, the limited coverage range of mm-wave (100m-200m) necessitate the presence of suitable techniques to reduce the outage probability due to propagation impairments. In this paper a dynamic multi state ultra-wideband millimeter wave frequency selection (DMSUWMF-S) is presented based on maximum SINR value at the user equipment (UE's). Two mmWave cellular cell deployment scenarios have been implemented with 2.2km × 2.2km and 3km × 3km based on cell range (150m and 200m) respectively. Three classes of millimeter wave base station according to the three frequencies 73, 38 and 28GHz have been simulated. The UE's have been uniformly generated throughout the simulation area. Based on the evaluation of our proposed scheme, the results have shown an enhancement of overall system performance with an increase in system capacity and reduced outage probability.