Waveguide-Fed Lens Based Beam-Steering Antenna For 5G Wireless Communications

In this paper, a two-dimensional cylindrical Lens antenna based on the parallel plate technique is designed. It supports beam-steering capability of 58° at 28 GHz. The antenna is composed of low loss rectangular waveguide antennas, which are positioned around a homogeneous cylindrical Teflon lens in the air region of two conducting parallel plates. The Beam scanning can be achieved by switching between the antenna elements. The main advantages of our design include its relative simplicity, ease of fabrication, and high-power handling capability. Compared to previous works including a curvature optimization for the plate separation of the parallel plates, the proposed antenna has a constant distance between plates. At the 28 GHz, the maximum simulated gain value is about 19 dB. Furthermore, the designed antenna only deviates about 0.4 dB over the 58° scan range

Study and Design of Array and Beamsteering Antennas for Millimeter Wave Band Application

Millimeter wave (mmWave) communication systems have attracted significant interest regarding supporting high data rate of Gigabit/s communications for the new generation of wireless communication networks. MmWave communication systems have frequency ranges in between 30 and 300 GHz wherein an enormous amount of unused bandwidth is available. Although the available bandwidth of mmWave frequencies is promising for high data rate communications, the propagation characteristics of mmWave frequencies are significantly different from microwave frequency band in terms of path loss, diffraction and blockage, and atmospheric absorption. In general, the overall losses of mmWave signals are significantly larger than that of microwave signals in point-to-point wireless communications. To compensate the high propagation losses, due to the limited output power that the current RF active components can deliver in millimeter waves, the use of directional and beam-steerable antennas become necessary in mmWave wireless systems. The use of directional antennas can effectively alleviate the signal interference in mmWave communications. High-gain directional antennas can be used at both the transmitting and receiving ends, resulting in a significantly enhanced Signal-to-Noise ratio (SNR) and improved data security, and can be used in long-range mmWave point-to-point communications. Moreover, directional antenna beams with limited spatial coverage need to be steered either electronically or mechanically to obtain a better substitute link for non-Line of Loss (LOS) communications. Therefore, this dissertation mainly focuses on antenna design for mmWave frequency band applications. High gain and beam-steerable antennas with the merits of low profile, high gain, high efficiency and low cost are studied to address the new challenges of high frequency band antennas. First, waveguide-based technology is employed to propose a new wideband high gain antenna for 60 GHz band applications. Then, for beam-steerable antenna applications to steer the antenna beam in a specific direction, different structures of cylindrical lens antennas are studied. First, a compact two-dimensional lens antenna is designed and proposed at 28 GHz, and then a possible design of a wideband beam-steerable lens antenna is discussed and presented. Finally, a fully metallic wideband metasurface-based lens antenna is explored. The antenna is realized based on an array of periodic unit-cells to reduce the loss of the dielectric part in the conventional lens antennas. This property is exploited to design wideband cost-effective fully metallic antenna at mmWave frequencies

60 GHz Waveguide-Fed Cavity Array Antenna by Multistepped Slot Aperture

This letter presents a center-feed high-gain and high-efficiency 4 × 4-element slot array antenna in the 60 GHz band. The antenna feed network is designed using only a single-layered square quad-ridge cavity structure, which is excited through a rectangular slot that has the same size as that of a standard WR-15 rectangular waveguide. The proposed antenna avoids any conventional power dividers in the feed network, which reduces the complexity of the design and fabrication process. To enhance the operating bandwidth of the antenna and prevent the grating lobes effects, a stepped design is used for each radiating slots of the array. Furthermore, the overall radiating aperture of the antenna is equipped with a dielectric layer, which decreases the mutual coupling among array elements. As a result, a broad bandwidth antenna with high efficiency and low sidelobes in both E- and H-planes is developed over the 60 GHz band. The antenna has been fabricated and tested. Measurement results show an operating bandwidth of 11.6% from 57.7 to 64.7 GHz. A gain of more than 23 dBi, sidelobes of less than -15.2 dB, and an antenna efficiency of better than 60% are achieved

Wideband Beam-Steerable Cylindrical Lens Antenna with Compact Integrated Feed Elements

In this paper, a wideband and compact high gain Lunenburg-based lens antenna for the Ka-band is proposed. The main potential applications are for 5G wireless communication systems and automotive radar applications. The antenna provides about 46.7% of bandwidth (|S11| ≤ -10 dB) covering a frequency band ranging from 23.6 - 38 GHz. It also exhibits excellent propagation characteristics with only a 2.7 dB maximum gain variation with sidelobe levels lower than -18 dB over the entire bandwidth. In addition, with a multi-feed system, the antenna presents a beam switching capability of ±32° in the azimuth plane with a gain fluctuation of less than 0.4 dB and sidelobes levels of less than -14 dB over the entire scan range. The simulated results show that the proposed antenna features a simple structure while supporting wider bandwidth and lower sidelobes levels when compared to that of Parallel plate waveguide (PPW) Luneburg-based lens antennas

A Compact and High Gain Dielectric-Loaded 60GHz Multi-Stepped Waveguide Antenna Array

In this paper, a wideband high-gain 2 × 2-element subarray is presented for 60 GHz applications. The antenna is fed with waveguide-fed cavity backed configuration and designed entirely via simple rectangular apertures. To improve radiation pattern characteristics and reduce the antenna size, steppedradiating apertures loaded with a solid dielectric material. A standard WR-15 rectangular waveguide is designed to excite the antenna at the input port over the operation frequency. The most significant advantage of using this design is its efficient radiation patterns, ability to decrease complexity and cost of fabrication. Simulated results demonstrate a maximum gain of about 19.5 dB, and the sidelobe level (SLL) of the antenna is less than -19 dB in E- and H-planes radiation patterns over the frequency range from 57.5 to 62.5 GHz. In contrast to previous works, the proposed antenna is much more simple to use in antenna array applications. Reduction in the number of radiating apertures and compact feeding networks will lower significantly the size and complexity of a large array with higher gain

Beam-Steering Lens Antenna for Point to Multipoint Communications at 28 GHz Band

In this article, we propose a new design of a multibeam cylindrical Luneburg lens antenna designed in the 28 GHz band. The proposed antenna is based on the parallel plate waveguide technique, in which the plates are separated by a fixed spacing and a homogenous dielectric material is applied between the plates. The most intuitive advantage of the proposed lens against the previous ones is the simplicity of the lens profile and volume, which is essential for the whole design and manufacturing processes for high-frequency applications. In addition, it provides a cost-effective and simple mechanical assembly. To reduce the losses associated with the feed elements, the lens is excited by an array of simple and compact integrated waveguide elements. The measured results show that the proposed antenna achieves a maximum gain of 17.73 dB and a maximum beam steering angle of 57.7° in the azimuth plane. Furthermore, the measured gain of the antenna varies by only 1 dB over the entire beam steering rang and the measured side lobe level of the antenna is less than −12.2 dB

Design of High Gain Single Layer Reflectarray Antenna Using Ring and Double Square Elements

A center feed reflectarray antenna is presented in this paper. Reflectarray antenna surface consists of the single layer unit cells. Each unit cell has a circular ring and a double square. Dimensions of the unit cells are selected such that a progressive phase shift is achieved at each unit cell. The Proposed reflectarray antenna has a gain of 30.86 dBi at 18 GHz. The designed antenna shows good performance in terms of gain and phase range. This makes our antenna design simple, cost-effective and lightweight as compared to other single layer reflectarray antennas

Electronically Controlled Unit Cell for Single Layer Reconfigurable Reflect-Array Antenna

A novel varactor loaded unit cell for reconfigurable single-layer reflectarray antenna is proposed in this work. The unit cell consists of a varactor loaded conducting pattern printed on the substrate over a ground plane. The phase of the reflected wave is varied by changing voltage across the varactor diode. By tuning varactor diode between 0.02 pF to 0.25 pF we can achieve the phase agility of 360° at the design frequency of 11 GHz. Despite single layer, the unit cell shows excellent characteristics in terms of phase range, figure of merit, reflection loss, and bandwidth. The proposed unit cell has a unique and novel geometry which attributes to its excellent radiation characteristics. The designed unit-cell structure is a good candidate for low cost and low profile reconfigurable reflectarray antenna designs

Design of High Gain Low Cost Beam-Steering Reflectarray Antenna

Design of a low cost and high gain reflectarray antenna is presented in this paper. A 28 × 28 element reflectarray surface has been designed for beam steering between -40° and +40° from the broadside. Unit cell of the reflectarray surface consists of a circular ring and a double square. The characteristics of the reflecting elements are selected such that a progressive phase shift is achieved. Beam steering can be achieved by switching between multiple feed antennas. Antenna shows a peak gain of 29.77 dBi at 18 GHz. In Comparison to the conventional beam steering antennas, the proposed antenna has higher gain and the design is cost effective to implement