Dual-Band Circularly Polarized Stack-Ring Antenna

A stack-ring configuration is proposed for designing a dual-band circularly polarized (CP) antenna. Each ring generates different resonant frequencies. A good CP performance at both resonant frequencies is achieved by adjusting the relative distance between the two rings. The two operating bands are separated with a small frequency ratio of 1.07. Measured results show that radiation patterns with good CP characteristics are obtained at the two resonant frequencies

Dual-Band Microstrip Patch Antenna with Switchable Orthogonal Linear Polarizations

This study presents a dual-band polarization-reconfigurable antenna that comprises a large square patch with a pair of corner-cut edges and two small square patches with a shorting via. Two PIN diodes are located between the large square patch and two small square patches. Depending on the bias state applied to the two PIN diodes, each small patch may be disconnected or connected to the large square patch. As a result, the proposed antenna can provide polarization reconfigurability between two orthogonal linear polarizations. Further, the proposed antenna operates at 2.51 GHz and 2.71 GHz. From the measured results, the proposed antenna shows a 10 dB bandwidth of 2.39% (2.49–2.55 GHz) and 2.58% (2.68–2.75 GHz). In this work, the frequency ratio can be easily controlled by changing the size of the small patch

Dual-Band Reconfigurable Antenna for Polarization Diversity

This paper proposes a dual-band reconfigurable square-ring antenna with a polarization diversity property. The proposed antenna consists of a square-ring resonator, two stubs with a shorting via, and two PIN diodes. The stub is positioned symmetrically to the left and right of the square-ring resonator, and the square-ring antenna connected to one of two stubs has a dual-band resonance. In this case, both resonant frequencies exhibit linear polarization (LP), and the two polarized waves are perpendicular to each other. The PIN diode selectively connects only one of the two stubs to the square-ring resonator. Thus, the polarization of the proposed antenna changes electrically at the two resonant frequencies. In addition, the frequency ratio (f2/f1) can be easily controlled by changing the length or width of the stub

Planar Printed Shorted Monopole Antenna with Coupled Feed for LTE/WWAN Mobile Handset Applications

A shorted monopole antenna with coupled feed for LTE/WWAN mobile handset applications is described. The basic resonance of the shorted monopole combines with the resonance formed by the coupling between the coupling strip and the feeding pad to cover the LTE700, GSM850, and GSM900 bands. Both the feeding pad and the coupling strip operate with the shorting strip as a loop antenna. The resonance of the loop antenna and the harmonics of the shorted monopole combine to cover the GSM1800, GSM1900, UMTS, and LTE2300 bands. A stable and omnidirectional radiation pattern with reasonable gain has been observed over the operating bandwidth

Endogenous Endophthalmitis Associated with Liver Abscess Successfully Treated with Vitrectomy and Intravitreal Empirical Antibiotics Injections

Purpose. Klebsiella pneumoniae is the most common pathogen of endogenous endophthalmitis accompanying liver abscess in East Asia. The treatment may be different for the patients with endogenous endophthalmitis from the postoperative endophthalmitis. Prompt administration of both intraocular (vancomycin and ceftazidime) and systemic (ceftriaxone, aminoglycoside, and/or metronidazole) antibiotics have been a mainstay of treatment. However, ceftriaxone has been proven to more effectively kill K. pneumoniae than ceftazidime in in vitro studies, and the safety of intravitreal ceftriaxone has been confirmed in animal studies. Methods. Two diabetic female patients with liver abscess presented with decreased visual acuity of the unilateral eyes. Fundus photography, ocular ultrasonography, and abdominal computed tomography were performed. Results. A 50-year-old diabetic female patient with liver abscess presented decreased visual acuity of the left eye. In fundus examinations, a yellowish necrotic lesion was noted throughout the eye. The results of culture of the blood culture was positive for K. pneumoniae. She was successfully treated with intravitreal ceftazidime injections, and the remaining vitreous opacity was treated with vitrectomy. A 62-year-old female with liver abscess presented a visual symptom of floaters in the right eye. The fundus had a hazy appearance through the vitreous opacity. A yellowish-white subretinal abscess was noted at the temporal macula. Cultures of blood were negative. She underwent intravitreal injections of empirical antibiotics. However, she did not respond to intravitreal vancomycin and ceftazidime. Thus, we changed the intravitreal antibiotics from ceftazidime to ceftriaxone and performed vitrectomy. Her ocular status significantly improved after this change. Conclusion. Our results indicate that for cases with EE, prompt initial treatment with broad spectrum antibiotics, followed by rapid use of antibiotics selected according to culture results, and empirical use of antibiotics in cases of a negative culture may be an effective treatment. Vitrectomy also can be an effective treatment option for vitreous opacity refractory to the treatment

Alumina‐Epoxy‐Pore Composites Fabricated by Inkjet Printing for Wireless Communication Technology

Abstract Reducing transmission loss via composites with pores has emerged as a breakthrough method for information and communications technology applications. The super/extremely high‐frequency signals used in the technologies result in significant transmission loss. Demand for low‐loss materials with low dielectric constant (Dk) and low dissipation factor (Df) has increased in recent years. Here, it is demonstrated that the pore in composites can be reduced Dk and Df of composites with pores (air). In fabrication of composites, a drop‐on‐demand (DOD) inkjet printing method to fabricate composites with pores (air) for use in wireless communications technologies. The DOD method is a simple but versatile manufacturing process at low cost. Its versatile process makes it possible to control the amount of resin and pore in fabrication of the composites and moreover to distribute all their components isotopically and homogeneously. It is possible to fabricate the composites with a lower Dk and Df value by increasing pore amount in the composites. This strategy enabled us to inexpensively manufacture dielectric substrates with low Dk and Df values, greatly contributing to the communications technology industry