Nikola Boskovic

High gain printed antenna array for FMCW radar at 17 GHz

We are presenting the design of a high gain printed antenna array consisting of 420 identical patch antennas intended for FMCW radar at Ku band. The array exhibits 3 dB-beamwidths of 2° and 10° in H and E plane, respectively, side lobe suppression better than 20 dB, gain about 30 dBi and VSWR less than 2 in the frequency range 17.1 - 17.6 GHz. Excellent antenna efficiency that is between 60 and 70 % is achieved by proper impedance matching throughout the array and by using series feeding architecture with both resonant and traveling-wave feed. Enhanced cross polarization suppression is obtained by anti-phase feeding of the upper and the lower halves of the antenna. Overall antenna dimensions are 31 λ0 × 7.5 λ0.

Compact frequency scanning antenna array with SRR phase shifters

We present a novel design of frequency-scanning array antenna which consists of eight antiresonant dipoles fed by balanced microstrip line. Feeding network contains four elongated split-ring resonators (SRRs) placed between dipoles to increase the frequency dependant phase difference between radiating elements. Split-ring resonators are with gap parallel and far from microstrip line that provides better matching in a wider frequency range in comparison to the similar SRRs with gap close to microstrip line. The beam scanning is found to be Δ=36° with frequency variation in the range from 5.7GHz to 6.1GHz and a very flat gain between 12.5 and 13.6dBi.

Long-term outcome of first 300 implanted Absorb bioresorbable vascular scaffolds in an all-comers Middle East population

Objectives To evaluate long-term clinical outcomes of the Absorb bioresorbable vascular scaffold (BVS) system (Abbott Vascular) in an all-comers Middle East population. Methods This prospective registry study included an initial set of patients with coronary lesions treated using Absorb BVS. Patients were followed for target vessel failure (TVF) including cardiac death, target vessel myocardial infarction (MI), and target lesion revascularization. Results A total of 217 patients (age, 55 ± 11 years; male, 169) with 300 treated lesions were included (median follow-up, 36 months [range, 26–41 months]; complete follow-up, 201 patients). Diabetes mellitus and acute coronary syndrome were present in 50% and 57% of patients, respectively. TVF rate was 32/201 (15.9%), including cardiac death in 10 (5%), target vessel MI in 13 (6.5%), and target lesion revascularization in 22 patients (10.9%). Definite or probable device thrombosis occurred in 11/201 patients (5.5%). TVF was associated with heart failure, worse ejection fraction, multi-vessel BVS, multi BVS in lesion, and total BVS length >50 mm. Conclusions Long-term outcome following Absorb BVS implantation in a population with high prevalence of high-risk and complex patients is acceptable, but heart failure, worse ejection fraction, and multi-vessel or long BVS implantation were associated with worse outcomes.

Improved Propensity-Score Matched Long-Term Clinical Outcomes in Patients with Successful Percutaneous Coronary Interventions of Coronary Chronic Total Occlusion

The objective of the study was to evaluate major adverse cardiovascular events (MACE) after successful versus failed percutaneous coronary intervention for chronic total occlusion (PCI-CTO).Limited data are available on long-term clinical follow-up in the treatment of chronic total occlusion (CTO).Between January 2009 and December 2010 PCI-CTO was attempted in 283 consecutive patients with 289 CTO lesions. Procedural success was 62.3% and clinical follow-up covered 83% (235/283) of the study population with a median follow-up of 66 months (range, 59-74).The total incidence of MACE was 57/235 (24.3%), and was significantly higher in the procedural failure group than in the procedural success group (33/87 (37.9%) versus 24/148 (16.2%), P < 0.001). All-cause mortality was significantly lower in patients with successful PCI-CTO compared to failed PCI-CTO (10.8% versus 20.7%, P < 0.05). Also, the rate of cardiovascular death in the procedural failure group (14.9%) was slightly higher than that in the procedural success group (7.4%, P = 0.066). The rate of TVR was statistically higher in the procedural failure group (P < 0.009). Propensity score-adjusted Cox regression showed that procedural success remained a significant predictor of MACE (adjusted HR 0.402; 95% CI 0.196-0.824; P = 0.013).Our study emphasizes the importance of CTO recanalization in improving long-term outcome including all-cause mortality with a borderline effect on cardiovascular mortality.

Printed Frequency Scanning Antenna Arrays With Enhanced Frequency Sensitivity and Sidelobe Suppression

This paper presents a novel design of the 1-D frequency scanning antenna array with enhanced scan sector, frequency sensitivity, and sidelobe suppression. The antenna is intended for the direct imaging radar sensors. Modified pentagonal dipoles with impedances ranging from 120 to

Frequency scanning antenna array with enhanced side lobe suppression

1070~\Omega

Printed scanning antenna array with SRR phase shifters

are used as radiating elements to provide the required sidelobe suppression. For the antenna design, new types of phase shifters are considered, with respect to their insertion loss, frequency bandwidth, phase shift, and manufacturing simplicity: the double-cell left-handed shifter and its right-handed counterpart. Four linear arrays with eight pentagonal dipoles are combined to obtain the antenna array with higher gain and narrower main beam with respect to constituent linear arrays, but with almost identical H-plane scanning properties. The proposed antenna array was manufactured, and the measured results show an increased scan sector of 55°, high frequency sensitivity of 14.25°/100 MHz, gain of 15.5–17 dBi, and low sidelobe levels of around −20 dB in the whole scanning frequency range. Measured results are in very good agreement with simulations.