Abstract Details
| Name: Anshu Kumari Affiliation: Indian Institute of Astrophysics Conference ID: ASI2016_712 Title : CROSS-POLARIZED LOG-PERIODIC DIPOLE ANTENNA FOR LOW FREQUENCY SOLAR OBSERVATIONS Authors and Co-Authors : G.V.S. Gireesh, C. Kathiravan, Indian Institute of Astrophysics,Bangalore Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : The solar coronal mass ejections (CMEs) play a direct and vital role in deciding the space weather, so it becomes inevitable to study their dynamical properties in the lower corona (i.e., over the heliocentric distance range: 1.05 – 2 Rʘ; where Rʘ = radius of the solar photosphere) both prior to and after the eruption. Since the CMEs are magnetically driven and often associated with different kinds of non-thermal energy releases, one can use the latter to infer the properties of CMEs and to estimate the strength of the associated magnetic field (B). Cross-polarized Log-Periodic Dipole Antennas (CLPDAs), a combination of two mutually orthogonal log-periodic dipole antennas mounted on a common axis, can be used to observe B over a broad frequency range. But such antennas are a rare commodity because of the difficulties involved in fabricating them. We present here the details of CLPDA, designed and developed in-house at the Gauribidanur observatory, to observe the polarized radio emission from the solar corona in the frequency range ~ 50 – 500 MHz. The solar radio emission in the above frequency range originates typically over the heliocentric distance range: 1.05 – 2 Rʘ. The measured cross-talk between the two orthogonal antennas in the CLPDA was < -30 dB in the above frequency range with the VSWR < 2 throughout. Trial observations indicate that the degree of circular polarization (dcp) can be measured to an accuracy of ~98% with the above CLPDA. Also, few trial observations were used to determine the strength of the magnetic fields responsible for type – III solar radio burst emissions. |