Phase management for extended scan range antenna arrays based on Rotman lens

This paper presents an implementation of a technique aimed to double the scanning range of a 24 GHz array antenna system based on Rotman lens beamforming. The new concept of the enhanced beam forming network consists of a combination of Rotman lens and 1-bit phase shifters, positioned in a peculiar way on the array side of the lens, and together with a particular beam arrangement allows to overcome the scan limitations which is typical of the standalone Rotman lens solution. Simulations will demonstrate that a Rotman lens, designed to steer the beam up to ±30°, when arranged in combination with properly designed Ratrace based phase shifters, allows to increase the scan range up to ±60°

Polarization reconfigurable patch antenna for compact and low cost UHF RFID reader

This paper presents a patch antenna designed for Ultra High Frequency (UHF) Radio Frequency IDentification (RFID) reader including a reconfigurable feeding for achieving polarization agility. The switchable polarization improves the polarization efficiency in comparison with standard circular polarized antenna solutions. CMOS switches are used in the reconfigurable feeding network for enabling higher power transmission and uncomplicated control with respect to solutions involving varactors and PIN diodes. Moreover, the designed patch antenna and ground planes have reduced size, for best integration of the reader in the required application. The combination of antenna and reconfigurable feeding network has been tested through simulations, showing good performance over the EU RFID frequency band (865-868 MHz). Due to its flexible and inexpensive structure, the proposed reconfigurable feeding system is a promising alternative to standard circular polarized reader antenna approaches

Phase shifters design for Rotman lens based beamforming network scan range extension

The design of the phase management unit needed for extending the scan range of a 24 GHz array antenna system based on Rotman lens beamforming is presented. The developed phase management unit consists of both static and switchable reflective type phase shifters, whose particular arrangement, in combination with a Rotman lens, allows increasing the maximum steering beam angle by 100%. Finally, the proposed concept is validated through simulation including the complete beamforming network and antenna array system

Frequency and Polarization Agile RFID Patch Antenna with Reduced Dimensions

This paper presents a frequency and polarization reconfigurable UHF RFID patch antenna based on a switchable feeding network. For best integration of the antenna, its size and ground plane are much smaller with respect to the canonical patch antenna design, however the proposed design is able to cover the EU and US frequency bands of the RFID standard. State-of-the-art CMOS switches are employed as key element for selecting the desired polarization and proper matching network. The switches provide also a simple solution for high power applications in contrast to concepts based on PIN diodes or varactors. Simulated results have shown good performance. Considering its flexible and inexpensive structure, the proposed system is a promising alternative to aperture tuning and circular polarized antenna approaches

Subcortical brain volume, regional cortical thickness, and cortical surface area across disorders: findings from the ENIGMA ADHD, ASD, and OCD Working Groups

Objective Attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and obsessive-compulsive disorder (OCD) are common neurodevelopmental disorders that frequently co-occur. We aimed to directly compare all three disorders. The ENIGMA consortium is ideally positioned to investigate structural brain alterations across these disorders. Methods Structural T1-weighted whole-brain MRI of controls (n=5,827) and patients with ADHD (n=2,271), ASD (n=1,777), and OCD (n=2,323) from 151 cohorts worldwide were analyzed using standardized processing protocols. We examined subcortical volume, cortical thickness and surface area differences within a mega-analytical framework, pooling measures extracted from each cohort. Analyses were performed separately for children, adolescents, and adults using linear mixed-effects models adjusting for age, sex and site (and ICV for subcortical and surface area measures). Results We found no shared alterations among all three disorders, while shared alterations between any two disorders did not survive multiple comparisons correction. Children with ADHD compared to those with OCD had smaller hippocampal volumes, possibly influenced by IQ. Children and adolescents with ADHD also had smaller ICV than controls and those with OCD or ASD. Adults with ASD showed thicker frontal cortices compared to adult controls and other clinical groups. No OCD-specific alterations across different age-groups and surface area alterations among all disorders in childhood and adulthood were observed. Conclusion Our findings suggest robust but subtle alterations across different age-groups among ADHD, ASD, and OCD. ADHD-specific ICV and hippocampal alterations in children and adolescents, and ASD-specific cortical thickness alterations in the frontal cortex in adults support previous work emphasizing neurodevelopmental alterations in these disorders

Reconstructive surgery for complex aortoiliac occlusive disease in young adults

BackgroundAlthough aortoiliofemoral bypass grafting is the optimal revascularization method for patients with severe aortoiliac occlusive disease (AIOD), previous studies have documented poor patency rates in young adults. This study investigated whether young patients with AIOD have worse outcomes in patency, limb salvage, and long-term survival rates after reconstructive surgery than their older counterparts.MethodsPatients aged ≤50 years undergoing reconstructive surgery at our institution for AIOD between 1995 and 2010 were compared with a cohort of randomly selected patients aged ≥60 years (two for each of the young patients, matched for year of operation), analyzing demographics, risk factors, indications for surgery, operative details, and outcomes.ResultsAmong 927 consecutive patients undergoing primary surgery for AIOD, 78 (8.4%) aged ≤50 years (mean age, 48.4 years) and 156 older control patients (mean age, 71.2 years) were identified. The younger patients were mainly men (81%) and 59% had surgery for limb salvage and 41% for disabling claudication (P = .02). Compared with older patients, they were significantly more likely to be smokers (90% vs 72%; P = .002) and had previously needed significantly more inflow procedures (28% vs 16%; P = .03). Only one death occurred perioperatively (30-day) among the control patients, and no major amputations or graft infections occurred in either group. The need for subsequent infrainguinal reconstructions was greater in the younger patients (18% vs 7%; P = .01). The primary patency rates were inferior in the younger patients at 5 years (82% and 75%) and 10 years (95% and 90%; P = .01), whereas assisted secondary patency (89% and 82% vs 96% and 91%; P = .08), secondary patency (93% and 86% vs 98% and 92%; P = .19), limb salvage (88% and 83% vs 95% and 91%; P = .13), and survival rates (87% and 76% vs 91% and 84%; P = .32) were comparable in the two groups.ConclusionsThis study shows that despite a higher primary graft failure rate than that in older patients, aortoiliofemoral revascularization for complex AIOD is a safe procedure for younger patients with disabling claudication or limb-threatening ischemia, providing they are willing to follow a regular protocol to complete their postoperative surveillance and to undergo graft revision as necessary