An electronically reconfigurable microstrip antenna with circular and linear polarization switching is presented. The prototype fabricated on a substrate of dielectric constant (ε r ) 4.4 and height ...(h) 1.6 mm is fed by a proximity feed fabricated using the same substrate. By controlling the bias voltage of two PIN diodes, the polarization of the antenna can be switched between three states; two states for linear polarization (horizontal and vertical) and one state for circular polarization (RHCP). Simulation and experimental results show that the proposed antenna has a cross polar level better than 10 dB in the linear polarization state and 18 MHz axial ratio bandwidth in the circular polarization state. The frequency and polarization diversities of this design could potentially improve the reliability of wireless communication systems.
A broadband printed microstrip antenna having cross polarization level >; 15 dB with improved gain in the entire frequency band is presented. Principle of stacking is implemented on a strip loaded ...slotted broadband patch antenna for enhancing the gain without affecting the broadband impedance matching characteristics and offsetting the position of the upper patch excites a lower resonance which enhances the bandwidth further. The antenna has a dimension of 42 × 55 × 4.8 mm 3 when printed on a substrate of dielectric constant 4.2 and has a 2:1 VSWR bandwidth of 34.9%. The antenna exhibits a peak gain of 8.07 dBi and a good front to back ratio better than 12 dB is observed throughout the entire operating band. Simulated and experimental reflection characteristics of the antenna with and without stacking along with offset variation studies, radiation patterns and gain of the final antenna are presented.
A Broadband L -Strip Fed Printed Microstrip Antenna Sarin, V P; Nishamol, M S; Tony, D ...
IEEE transactions on antennas and propagation,
2011-Jan., 2011, 2011-01-00, Letnik:
59, Številka:
1
Journal Article
Recenzirano
A broadband <;i>;L<;/i>; -strip fed printed microstrip antenna is presented. The strip loaded slotted broadband microstrip antenna is fed by an L -strip feed line to achieve impedance matching for ...the higher order modes of the patch antenna in addition to the existing resonances. The antenna offers 74% bandwidth when printed on a substrate of dielectric constant 4.2 and has an overall dimension of 42 × 55 × 3.2 mm 3 . The simulated and experimental reflection characteristics of the antenna with and without the L -feed along with radiation patterns, input impedance variations, gain and efficiency of the final antenna are presented and discussed. The time domain transient analysis indicates a minimum dispersion to the transmitted pulse.
Diverse stimuli can feed into the MAPK/ERK cascade; this includes receptor tyrosine kinases, G protein-coupled receptors, integrins, and scavenger receptors (LDL receptor-related protein (LRP)). ...Here, we investigated the consequence of concomitant occupancy of the receptor tyrosine kinases (by EGF, basic FGF, VEGF, etc.) and of LRP family members (by LDL or lactoferrin). The simultaneous stimulation of a receptor tyrosine kinase by its cognate ligand and of LRP-1 (by lactoferrin or LDL) resulted in sustained activation of ERK, which was redirected to the cytoplasm. Accordingly, elevated levels of active cytosolic ERK were translated into accelerated adhesion to vitronectin. The sustained ERK response was seen in several cell types, but it was absent in cells deficient in LRP-1 (but not in cells lacking the LDL receptor). This response was also contingent on the presence of urokinase (uPA) and its receptor (uPAR), because it was absent in uPA−/− and uPAR−/− fibroblasts. Combined stimulation of the EGF receptor and of LRP-1 delayed nuclear accumulation of phosphorylated ERK. This shift in favor of cytosolic accumulation of phospho-ERK was accounted for by enhanced proteasomal degradation of dual specificity phosphatases DUSP1 and DUSP6, which precluded dephosphorylation of cytosolic ERK. These observations demonstrate that the ERK cascade can act as a coincidence detector to decode the simultaneous engagement of a receptor tyrosine kinase and of LRP-1 and as a signal integrator that encodes this information in a spatially and temporally distinct biological signal. In addition, the findings provide an explanation of why chronic elevation of LRP-1 ligands (e.g. PAI-1) can predispose to cancer.
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