Low-Cost Beam Steerable Antennas Using Parasitic Elements

Beam steerable antennas are considered as a possible solution for meeting challenges in military and civilian systems such as satellite communication networks, automotive collision avoidance radar, base stations and biomedical applications. Phased array antennas are a natural choice as the foundation for many steerable antenna platform due to its exibility and gain scalability. The implementation of a phased array requires a large number of electronic components, tending to drive the cost of phased arrays and limit their usage to military applications. The electrically steerable parasitic array radiator (ESPAR) has been introduced as an antenna which is capable of adaptively controlling its beam pattern using parasitic elements loaded with varactors. ESPAR has attracted the attention of researchers from the desire for electrically scanned beams with inexpensive fabrication and has found as a suitable candidate for communication systems applications, including advanced radars, cellular base stations and space communications. The ultimate goal of this research is to design and propose state of the art designs in the �eld of ESPAR that can satisfy the requirements of today's advanced communication systems, which should be cost-e�ective and can compete with other rival technologies. Considering the potentials of ESPAR, it can be proved that it is a good candidate for modern wireless communications. The thesis presents several contributions related to the design and analysis of ESPAR technology using dielectric resonator antenna (DRA) as the main radiator element. First, the thesis presents solutions to alleviate the problems associated in implementing a large ESPAR. The large array is useful in many applications since some required recon�gurable radiation characteristics may not be achievable with a single ESPAR element. The proposed structure consists of 240 perforated DRAs, whichare uniformly excited by a parallel-series feeding network. By employing the perforation technique, the need for aligning and bonding individual DRA is eliminated. The subarrays are placed in an interleaved arrangement to suppress the grating lobes. The proposed large ESPAR can incredibly reduce the number of phase shifter by 80% in comparison with the conventional phased array, which makes it inexpensive. Second, the thesis investigates potentials of ESPAR for massive multi-input multiple output (MIMO) communication. Massive MIMO technology has attracted tremendous interest due to its capabilities in enhancing the data transmission capacity, increasing the reliability, and reducing the multipath fading. However, in this technology for feeding each individual antenna, one radio frequency chain is required that can increase the power consumption and complexity of the structure. Moreover, to obtain decorrelated channels and to reduce mutual coupling, the antenna should be spaced suffciently far from each other that imposes increased physical dimensions. In contrast to the conventional MIMO structures, in ESPAR only one RF chain is needed and the small size constraint turns to be an advantage as the mutual coupling is exploited to form the desired signals. Furthermore, by controlling the tunable loads at each parasitic antenna element, different radiation patterns can be formed which can signi�cantly improve the performance of a MIMO antenna system operating in a changing environment. Thus, by using the advantages of ESPAR, a design approach to address the size and cost issues is proposed through this work. The proposed design is validated by simulation and measurement of a prototype, and results include the antenna and MIMO �gure of merits such as radiation patterns, efficiency, S-parameters, signal correlations, total active reection coeffcient (TARC), and channel capacity. These results have demonstrated that the proposed ESPAR design can be successfully implemented for a massive MIMO structure. Finally, the thesis presents an effective method to design a ESPAR with a circularly polarized (CP) beam-scanning feature. Circular polarization is an ideal polarization due to its advantages in signal propagation properties, which can address the di�culties associated with mobility, inclement weather conditions, and immunity to multi path distortion. In this work, the CP beam steering is achieved by adopting a sequential rotation approach for placing the parasitic antennas that are loaded with tunable varactors. The proposed CP-ESPAR technique eliminates the need of expensive phase shifters, which signi�cantly reduces cost and fabrication complexity. For performance evaluation, a prototype of the proposed antenna is designed, fabricated, and measured. It is observed that the proposed antenna has a monotonic CP beam scanning from { 22 to 22 operating at 10.5 GHz

GGPS1-associated muscular dystrophy with and without hearing loss

Ultra-rare biallelic pathogenic variants in geranylgeranyl diphosphate synthase 1 (GGPS1) have recently been associated with muscular dystrophy/hearing loss/ovarian insufficiency syndrome. Here, we describe 11 affected individuals from four unpublished families with ultra-rare missense variants in GGPS1 and provide follow-up details from a previously reported family. Our cohort replicated most of the previously described clinical features of GGPS1 deficiency; however, hearing loss was present in only 46% of the individuals. This report consolidates the disease-causing role of biallelic variants in GGPS1 and demonstrates that hearing loss and ovarian insufficiency might be a variable feature of the GGPS1-associated muscular dystrophy

Dual band-notched monopole antenna with enhanced bandwidth for ultra-wideband wireless communications

A new configuration of an ultra-wideband (UWB) dual band-notched antenna is presented. The designed geometry consists of octagonal radiating patch, a 50 Ω microstrip feed-line on the front and an asymmetric partial ground on the back. For impedance bandwidth enhancement, a unilateral stepped structure is utilised on the ground. By etching two E-shaped slots connected to each other on the radiating patch and applying E-shaped defected ground structure on the back, dual notched bands are achieved. The antenna is printed on a low profile FR4 substrate with a compact size of 25 × 18 × 1 mm^3. The experimental results indicate that the antenna has an impedance bandwidth from 2.55 to 21.65 GHz for voltage standing wave ratio ≤2, except the notched bands on worldwide interoperability for microwave access and wireless local area network bands. Moreover, stable radiation patterns and gains within the operating band are shown

Biallelic PRMT7 pathogenic variants are associated with a recognizable syndromic neurodevelopmental disorder with short stature, obesity, and craniofacial and digital abnormalities

PURPOSE: Protein arginine methyltransferase 7 (PRMT7) is a member of a family of enzymes that catalyzes the methylation of arginine residues on several protein substrates. Biallelic pathogenic PRMT7 variants have previously been associated with a syndromic neurodevelopmental disorder characterized by short stature, brachydactyly, intellectual developmental disability, and seizures. To our knowledge, no comprehensive study describes the detailed clinical characteristics of this syndrome. Thus, we aim to delineate the phenotypic spectrum of PRMT7-related disorder. METHODS: We assembled a cohort of 51 affected individuals from 39 different families, gathering clinical information from 36 newly described affected individuals and reviewing data of 15 individuals from the literature. RESULTS: The main clinical characteristics of the PRMT7-related syndrome are short stature, mild to severe developmental delay/intellectual disability, hypotonia, brachydactyly, and distinct facial morphology, including bifrontal narrowing, prominent supraorbital ridges, sparse eyebrows, short nose with full/broad nasal tip, thin upper lip, full and everted lower lip, and a prominent or squared-off jaw. Additional variable findings include seizures, obesity, nonspecific magnetic resonance imaging abnormalities, eye abnormalities (i.e., strabismus or nystagmus), and hearing loss. CONCLUSION: This study further delineates and expands the molecular, phenotypic spectrum and natural history of PRMT7-related syndrome characterized by a neurodevelopmental disorder with skeletal, growth, and endocrine abnormalities

Biallelic PRMT7 pathogenic variants are associated with a recognizable syndromic neurodevelopmental disorder with short stature, obesity, craniofacial and digital abnormalities

PurposeProtein arginine methyltransferase 7 (PRMT7) is a member of a family of enzymes that catalyzes the methylation of arginine residues on several protein substrates. Biallelic pathogenic PRMT7 variants have previously been associated with a syndromic neurodevelopmental disorder characterized by short stature, brachydactyly, intellectual developmental disability, and seizures. To our knowledge, no comprehensive study describes the detailed clinical characteristics of this syndrome. Thus, we aim to delineate the phenotypic spectrum of PRMT7-related disorder.MethodsWe assembled a cohort of 51 affected individuals from 39 different families, gathering clinical information from 36 newly described affected individuals and reviewing data of 15 individuals from the literature.ResultsThe main clinical characteristics of the PRMT7-related syndrome are short stature, mild to severe developmental delay/intellectual disability, hypotonia, brachydactyly, and distinct facial morphology, including bifrontal narrowing, prominent supraorbital ridges, sparse eyebrows, short nose with full/broad nasal tip, thin upper lip, full and everted lower lip, and a prominent or squared-off jaw. Additional variable findings include seizures, obesity, nonspecific magnetic resonance imaging abnormalities, eye abnormalities (i.e., strabismus or nystagmus), and hearing loss.ConclusionThis study further delineates and expands the molecular, phenotypic spectrum and natural history of PRMT7-related syndrome characterized by a neurodevelopmental disorder with skeletal, growth, and endocrine abnormalities