Antenna Designs Aiming at the Next Generation of Wireless Communication

Millimeter-wave (mm-wave) frequencies have drawn large attention, specically for the fifth generation (5G) of wireless communication, due to their capability to provide high data-rates. However, design and characterization of the antenna system in wireless communication will face new challenges when we move up to higher frequency bands. The small size of the components at higher frequencies will make the integration of the antennas in the system almost inevitable. Therefore, the individual characterization of the antenna can become more challenging compared to the previous generations.This emphasizes the importance of having a reliable, simple and yet meaningful Over-the-Air (OTA) characterization method for the antenna systems. To avoid the complexity of using a variety of propagation environments in the OTA performance characterization, two extreme or edge scenarios for the propagation channels are presented, i.e., the Rich Isotropic Multipath (RIMP) and Random Line-of-Sight (Random-LoS). MIMO efficiency has been defined as a Figure of Merit (FoM), based on the Cumulative Distribution Function (CDF) of the received signal, due to the statistical behavior of the signal in both RIMP and Random-LoS. Considering this approach, we have improved the design of a wideband antenna for wireless application based on MIMO efficiency as the FoM of the OTA characterization in a Random-LoS propagation environment. We have shown that the power imbalance and the polarization orthogonality plays major roles determining the 2-bitstream MIMO performance of the antenna in Random-LoS. In addition, a wideband dual-polarized linear array is designed for an OTA Random-LoS measurement set-up for automotive wireless systems. The next generation of wireless communications is extended throughout multiple narrow frequency bands, varying within 20-70 GHz. Providing an individual antenna system for each of these bands may not be feasible in terms of cost, complexity and available physical space. Therefore, Ultra-Wideband (UWB) antenna arrays, coveringmultiple mm-wave frequency bands represent a versatile candidate for these antenna systems. In addition to having wideband characteristics, these antennas should offer an easy integration capability with the active modules. We present a new design of UWB planar arrays for mm-wave applications. The novelty is to propose planar antenna layouts to provide large bandwidth at mm-wave frequencies, using simplified standard PCB manufacturing techniques. The proposed antennas are based on Tightly Coupled Dipole Arrays (TCDAs) concept with integrated feeding network

Study, design and fabrication of a two-dimension beam scanning antenna in package

Various emerging high data-rate applications such as ultra-high definition video streaming and wireless personal area networks have made the transition to the next generation communication systems at mmWave frequencies inevitable. Moreover, the antenna in package has been proved to be a suitable solution for a compact and efficient antenna system platform at this frequency range. Due to smaller wavelengths and aperture illumination at this frequency range, these antennas tend to have a limited radiation gain which consequently results into a limited connection range. To compensate, a high gain array antenna structure with beam steering capability is inevitable. Moreover, current developed mmWave frequency scanning antennas suffer from some shortcomings such as using active phase shifters, narrow impedance bandwidth, limited scanning range, lack of circular polarization, one dimensional beam steering, neglected electromagnetic interference, and non-efficient inter-layer interconnects. In view of these issues, the initial objective of this thesis is to study different antenna packaging methods as well as the recent developments in mmWave frequency and scanning antenna structures in order to design and produce a performant system. Consequently, a new design for a wideband circularly polarized frequency scanning periodic leaky-wave antenna has been proposed and tested which features a wide seamless scanning range of about 95° including the broadside and a fractional -10 dB impedance bandwidth of about 47%. Moreover, an accurate empirical model is developed for this antenna, as well as optimization methods to minimize the side lobe level and the axial ratio. In order to integrate band-pass filtering capability, a modified version of this antenna is also developed and tested in the scope of this research. With the goal of integrating band-pass filtering capability into the inter-layer transitions, new types of broadside coupled multi-layer filters have been designed and tested. With a fractional bandwidth of about 40% at the center frequency of 25 GHz, these filters are compact, tunable, and have a simple structure that makes them suitable candidates for replacing via interconnects in multi-layer antenna in package configurations. Finally, the antenna is combined as a linear phased array structure with a Rotman lens beamformer in a multi-layer structure to perform beam scanning in two dimensions. This system is designed and fabricated at 25 GHz and can steer the radiation beam in both E (90º) and H (60º) planes without any active phase shifter. The beamforming performance is preserved in a wideband frequency range from 20 to 30 GH and the undesired signals out of this band are attenuated using the integrated band pass filters

A 37-40 GHz Dual-Polarized 16-Element Phased-Array Antenna with Near-Field Probes

With the development of fifth-generation (5G) communication networks, in order to meet the growing demand for high-speed and low-latency wireless communication services, channel capacity has become the main driving force for choosing millimeter wave (mm-wave) over over-crowded sub-6 GHz frequency bands. Recently, beamforming phased array attracts significant research efforts as it is a promising solution and unique in its ability to overcome the high path-loss at high frequency, provide fast beam steering and deliver better user-ends experience. However, to alleviate the issues that associated with beamforming phased array, such as imbalance between array elements and non-linearity caused by power-amplifiers (PAs) in beamforming channels, far-field (FF) based array calibration and digital pre-distortion (DPD) need to be performed, which is not practical in real world scenario. This thesis presents a low-cost 16-element dual-polarized mm-wave antenna-on-printed circuit board (PCB) transmitter RF beamforming array with embedded near-field probes (NFPs) at 37-40 GHz. The elements are orthogonal, proximity-coupled feed dual-polarized patch antenna with a spacing of 0.5λ within 2x2 subarray and 0.6λ between 2x2 subarray at 38.5 GHz, resulting in maximum 17.7 dB gain with a scan angle of +/-50◦, +/-20◦ in azimuth and +/-20◦, +/-50◦ in elevation for vertical polarization and horizontal polarization, respectively. Without affecting phased array performance, the NFPs achieve flat and comparable coupling magnitude and group delay to the closet RF chain for both polarizations, across operating frequency range. This ensures the quality of received output signal from phased array to implement array calibration and DPD. The configuration of embedded NFPs maintains the scalability of phased array and eliminate the needs of impractical FF reference probe for array calibration and DPD

Solid State Technology Branch of NASA Lewis Research Center

A collection of papers written by the members of the Solid State Technology Branch of NASA LeRC from Jun. 1991 - Jun. 1992 is presented. A range of topics relating to superconductivity, Monolithic Microwave Circuits (MMIC's), coplanar waveguides, and material characterization is covered

Design of 28 GHz 4x4 RF Beamforming Array for 5G Radio Front-Ends

Current state of wireless infrastructure sees mass migration to higher frequencies as much of the already used spectrum is insufficient in supporting the influx of numerous users and various data intensive mobile applications. Data rates are projected to increase by an order of magnitude and harnessing the necessary bandwidth below 6 GHz is not feasible. A move to higher frequencies sees not only increased fractional bandwidth, but also significantly enhanced antenna apertures as a result of beamforming capabilities. Due to device level complications with frequencies nearing the unit gain frequency of transistor technology, high output power is seldom found, and in conjunction with severe path loss, communication links cannot be established without the usage of antenna arrays. Phased array systems offer significant upside to the traditional array implementation as it permits reconfigurable directive communication. However, Ka-Band phased arrays still struggle to arrive at a reasonable tradeoff between design complexity, cost and performance. With a divide between both organic and printed circuit board (PCB) based approaches to the development of an antenna-in-package (AiP), this thesis sides with the latter. An antenna-on-PCB variant of the AiP is developed, which implements both commercially available RF laminates and RFIC front end modules to produce a 28 GHz 4x4 RF beamforming phased array that is found to exhibit extremely low loss (-0.66 dB), adequate scan volume (+/- 45 degrees, in E and H planes) and large bandwidth (3 GHz) for a single layer, non-isolated patch antenna design. Unit cell, infinite array analysis is emphasized and lattice resizing is leveraged to obtain desired scan performance, while significantly reducing design complexity via the absence of intricate isolation enhancement techniques. In an effort to aid in application based design, the AiP is extended to application of linearization where it is found that the inclusion of dummy elements along the perimeter of the package not only serve as element pattern enhancement, but also provide reliable means of output signal capture. Negating the traditional transmitter observation receiver (TOR) architecture, the AiP design as a TOR for millimeter-wave communication proves optimistic in the quest for maximum system efficiency

Beam-switching antennas for millimeter-wave communications

Millimeter-wave frequencies, i.e. 30-300 GHz, are being widely adopted in commercial applications such as communication systems, radar, and imaging. At millimeter-wave frequencies, the antennas need to be directive to mitigate the higher free-space loss and atmospheric attenuation. In addition, the beam steering capability helps to extend the coverage to a wide angular range. The objective of the thesis is to develop high-gain and wide beam-steering antennas based on the beam-switching topology. The thesis contributes to the improvement of the integrated lens antenna (ILA) and the feed beam-switching network (BSN) performance. The ILAs are evaluated in terms of form-factor and scan-loss reduction and efficiency improvement. The study of BSN is aimed towards insertion loss reduction and enabling beam reconfigurability. An elliptical ILA with a focal length to diameter ratio, f/d, of 1.1 and a diameter of 160 mm is designed to meet the gain and beam-steering regulations for the point-to-point link antennas operating at 71-76 GHz. The f/d of an elliptical ILA is reduced to 0.88 by using the high permittivity material. An integrated metal-plate lens (IMLA), a combination of the dielectric and metal-plate lens, is proposed to reduce the focal length. The IMLA with 0.69 f/d is designed to achieve a total efficiency of 64% in comparison to 45% of the traditional ILA. The radiation pattern tilting of the offset feeds along the focal plane improved the scan loss of the IMLA by 3.5 dB compared to a traditional ILA. Furthermore, the reduction of scan loss and the extension of the beam steering range of the hemispherical ILA is achieved by positioning the feeds along the spherical surface. The second part of the thesis focuses on the BSN. The numerical study demonstrates that the ILA radiation properties are mostly affected by the radiation pattern distortion of the beam-switching feed array rather than the coupling between the feed ports. The BSN of the Rotman lens fed array is implemented with the 4-channel vector modulator (VM) instead of the RF-switch to minimize the insertion loss. The Rotman lens-based array uses the 1×4 SIW-fed microstrip patch antenna arrays as the radiating elements and a novel easy-to-implement admittance control mechanism is demonstrated for the SIW-fed series arrays. The beam-configurability of the Rotman lens-based array is attained by simultaneous excitation of the beam ports with the VM, which varies the half power beamwidth from 18° to 75°

MEMS-Based Millimeter Front-end for Automotive Radar Applications

Automotive front-end radars are key components in modern vehicles. They are used in automatic cruise control (ACC) for advanced drive-assistance and security functions, including collision-avoidance systems. Automotive safety is being studied intensively both in industry and academia. One of the most serious limitations of high performance radar are beam-forming network systems, due to the complexity and bulkiness arising from the additional circuitry and hardware needed to implement multiple functionalities into the systems. This limitation can, however, be minimized and made cost-effective by capitalizing on the numerous advantages of RF MEMS and WG technologies. To resolve this issue, the present study covers the characterization of SPST and SPNT RF-MEMS switches at 77 GHz, the investigation and fabrication of a Rotman lens at 77 GHz, and the development of the ground work for a 3D monolithically integrated BFN on a single silicon substrate

Advanced Syncom, volume 1 Summary report

Synchronous communications satellite configuration, instrumentation, handling and test equipment, and systems desig

A Modular and Scalable Architecture for Millimeter-Wave Beam-forming Antenna Systems

As the demand for higher data rates increases, wireless technologies (e.g., satellite communications, fifth Generation (5G) wireless communications, and automotive radars) are migrating toward millimeter-wave (mm-W) frequencies (30-300 GHz) to utilize the numerous unused spectra available over this frequency band. For truly ubiquitous coverage over the globe, high throughput Ka-band satellite communication (SATCOM) offers the most optimal and a unique solution for providing world-wide information and sensing. Of particular interest is the development of land, or close-to-land, mobile systems for high data rate communications with continuous coverage for on-the-move commercial platforms, including cars, airplanes, ships, and trains. A modular and scalable phased-array antenna (PAA) architecture wherein the entire phased-array system is made of identical sub-array modules (building blocks) is the most promising approach to develop cost effective and flexible systems for mass market applications. Obviously, such architecture depends on the availability of a high-performance antenna element, antenna subarray modules, and beam-forming circuits. These are the main topics investigated in this PhD thesis. Two approaches were extensively studied in this PhD research to develop intelligent steerable antenna array modules as building blocks for large-scale Ka-band SATCOM applications. The first approach targeted the development of a working prototype for a wide-angle beam-steering Ka-band active PAA (APAA). In this approach, two APAA architectures were proposed, designed, fabricated, and measured to validate the proposed concepts. Both approaches exhibit wide beam-steering angles and fast beam-forming capabilities with full control on amplitude and phase of each antenna element by utilizing an intelligent beam-forming circuit that was developed at CIARS (Centre for Intelligent Antenna and Radio Systems). The first architecture comprises a novel single-fed CP antenna element integrated with the intelligent beam-forming circuit, to construct a wide beam-steering and low-cost CP-APAA. A 4×16 CP-APAA was designed and fabricated using low-cost printed circuit board (PCB) technology and it was tested over the frequency range (29.5-30 GHz) over an angular range of 0o-±40o. The second architecture utilized a highly integrated and wide band dually-polarized antenna element as a core component for the realization of a high-performance, compact, and polarization-agile Ka-band APAA module. The proposed antenna module was used to construct a proof-of-concept 16×16 modular APAA to radiate a high polarization purity pattern over a wide beam-steering angles ≥70o. The second proposed approach investigated two novel wideband and passive steerable antenna concepts as attractive low-cost alternatives suitable for a wide range of emerging mm-W communication systems. Such antenna systems are made of passive components, antennas, phase shifters, and passive feeding networks to reduce the power consumption, cost, and complexity of conventional active electronically steered arrays. In order to build such systems, a high-performance antenna and passive phase shifter (invented at CIARS) were integrated to eliminate the necessity for costly variable gain amplifiers (VGAs). The first proposed concept is a novel CP passive PAA comprised of the proposed single-fed CP antenna integrated with the CIARS phase shifter. The novel high-performance passive phase shifter was controlled by a low-profile and low-power consumption novel magnetic actuator to overcome the limitation of state-of-the-art passive phased arrays. The proposed CP passive PAA was designed, fabricated and tested at Ka-band (29.5-30.5 GHz) over an angular range of 0o-±38o. The second concept proposed here is a novel reconfigurable reflectarray antenna (RAA) element with a true-time-delay functionality. Its reconfigurability is realized by utilizing the proposed phase shifter integrated with an aperture-coupled microstrip patch antenna (ACMPA) to receive and re-radiate the electromagnetic energy efficiently. The proposed RAA element was designed and tested at Ka-band (27.5-30 GHz)