http://nopr.niscair.res.in/handle/123456789/3764 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/3997 Title: Contribution of higher pitch angles in sideband generation <br/> <br/>Authors: Singh, D P; Singh, U P <br/> <br/>Abstract: Non-linear cyclotron resonance between energetic electrons and Siple (Antarctica) transmitted VLF signals in the magnetosphere is considered as the cause of sideband generation observed in received spectrograms recorded at ground station situated at Roberval (Canada). The role of higher pitch angles (> 45°) in producing observed average spacing (30-60 Hz) is studied. It is shown that observed average spacing can only be produced if interacting electrons pitch angle (⍺) is greater than 45° and spacing increases with increase in pitch angle and wave magnetic amplitude as well. <br/> <br/>Page(s): 59-61 http://nopr.niscair.res.in/handle/123456789/3996 Title: Performance of cavity backed inverted microstrip broadband antenna <br/> <br/>Authors: Iqbal, Sheikh Sharif; Biswas, Manotosh; Siddiqui, Jawad Y.; Guha, Debatosh <br/> <br/>Abstract: An inverted microstrip circular patch with a parasitic element printed back-to-back on the same substrate and backed by a cylindrical metallic cavity is investigated as a compact integratable broadband antenna. The cavity effect in changing its impedance behaviour is thoroughly examined and an optimized X-band design is presented. As much as 11% bandwidth is apparent from the design data. Principal plane radiation patterns are also examined, showing above 98% efficiency and 10.97 dB directivity. <br/> <br/>Page(s): 54-58 http://nopr.niscair.res.in/handle/123456789/3995 Title: MOS capacitor integrated microstrip antenna <br/> <br/>Authors: Gautam, Anil K; Vishvakarma, B R <br/> <br/>Abstract: An MOS capacitor integrated microstrip antenna is proposed, in which the operating frequency of the rectangular microstrip antenna is electronically controlled with the bias voltage of the MOS capacitor. Theoretical investigations based on a modal cavity model are carried out for the MOS capacitor integrated microstrip antenna. The tuning range was found to be 4.6836 GHz (110.08 %) in comparison to that (76.08 %) reported earlier. <br/> <br/>Page(s): 47-53 http://nopr.niscair.res.in/handle/123456789/3994 Title: Probability of sideband generation at low latitudes <br/> <br/>Authors: Singh, D P; Singh, U P <br/> <br/>Abstract: Possibility of sideband generation at low, middle and high latitudes is studied considering non-linear interaction between resonant electrons and very low frequency signals transmitted into the magnetosphere. It is shown that as <i style="">L</i> value increases, sideband spacing decreases and, at low <i style="">L</i> shells, frequency difference of 1500 Hz in interacting signals (i.e. from 2500 to 4000 Hz or from 4000 to 5500 Hz) produces insignificant spacing values. It is also shown that mean fractional spacing at low latitudes is more than maximum(observed) fractional spacing at <i style="">L </i>= 4, indicating that sideband generation at low latitudes has a remote possibility. <br/> <br/>Page(s): 22-25