A Dual-Band Dual-Polarized Omnidirectional Antenna

A dual-band dual-polarized omnidirectional antenna is investigated. The two bands are generated by a lower circular patch and an upper circular patch, respectively. A set of conductive vias and a coupled ring are utilized to widen the antenna bandwidth. Curved branches are introduced to contribute to circularly polarized radiation. A prototype was designed, fabricated and measured to demonstrate the performance of the antenna. Measured results show that an overlapped bandwidth of 15% from 2.22 to 2.58 GHz for both S11 ≤ −10 dB and axial ratio ≤3 dB is obtained in the low band, and an impedance bandwidth of 11.1% from 5.63 to 6.29 GHz is achieved in the high band. Measured peak gains are approximately 4.3 dBic and 5.4 dBi at two bands. Moreover, omnidirectional radiation patterns are also obtained within the operating band.

Laser Conoscopy of Optically Active Crystals

The article discusses a laser conoscopic method for studying optically active crystals in order to determine such optical characteristics as the sign of rotation of the polarization plane and the optical sign of an optically active crystal from its interference conoscopic pattern obtained with circularly polarized radiation. Such a conoscopic pattern in the form of two spirals inserted into each other allows one to simultaneously and reliably determine the indicated characteristics by the orientation of the spirals and the direction of their twisting for an optically active crystal.

A Novel Dual-Broadband Circularly Polarized Patch Antenna for Precise Satellite Navigation

This paper presents a novel dual-band circularly polarized patch antenna for precise satellite navigation. The radiation elements are composed of the inner cross-shaped patch and the outer annular patch which are printed on the same surface of one substrate. Two patches work in different bands, respectively, and emit dual-band circularly polarized radiation. In order to obtain a more compact antenna to meet the application of precise satellite navigation, we vertically place four metal cylinders under the ends of the cross-shaped patch to form four capacitive loadings to lower the resonant frequency of the inner cross-shaped patch. A capacitive coupling feed structure is used to match the input impedance of a patch antenna and make the antenna compact enough. The simulated and measured results show that the proposed antenna can produce appropriate dual-band circularly polarized radiation patterns for precise satellite navigation. The measured results of the antenna illustrate that maximum RHCP gain of the antenna is 4.72 dBi in the low band and 3.98 dBi in the high band, the 3 dB gain bandwidth is 70 MHz in the low band and 65 MHz in the high band.

A Slotted Single Feed Circularly Polarized Microstrip Patch Antenna with Suppressed Surface Wave Losses for WLAN Applications

The circularly polarized microstrip antenna has been of great importance in WLAN applications. A circularly polarized slotted circular patch antenna with co-axial feed geometry has been designed to meet the requirements. The antenna designed has been slotted at several locations to make it radiate circularly polarized radiation. Two metallic cylindrical vias have been inserted near the two diametric ends of the slot to improve the realized gain of the antenna. The antenna structure is resonating at 6.4 GHz with 3dB axial ratio bandwidth of 200MHz and gain of 9.8dB has been observed.

Theoretical Basis for Switching a Kramers Single Molecular Magnet by Circularly-Polarized Radiation

The d-group Kramers ions, having strong zero field splitting (ZFS) with axial symmetry and a negative D value for the ZFS Hamiltonian, are widely considered as candidates for use as single molecular magnets (SMMs). An important need is the means to switch the SMM between its states in a reasonably short and predictable period of time, which is generally not available. We propose an approach, Zeeman–far infrared (ZeFIR) double resonance, in which circularly polarized alternating magnetic fields in the far infrared (FIR) range induce selective magnetic dipole transitions between different Kramers doublets of the SMM and polarized microwave (mw) pulses transfer excitation inside the upper Kramers doublet. A combination of FIR and mw pulses allows unidirectional switching between +S and –S states of the ion. The proposed approach is considered for a model quartet system with total spin S = 3/2, which seems to be the most promising object for selective resonance manipulations of its states by circularly polarized radiation.