Welcome to the AMTA paper archive. Select a category, publication date or search by author.
(Note: Papers will always be listed by categories. To see ALL of the papers meeting your search criteria select the "AMTA Paper Archive" category after performing your search.)
Paper not available for presentation.
The loop cell is fabricated using two intersecting metal sheets joined at the intersection and forming a 36 deg angle. A section of a loop is mounted between two coaxial panel jacks, one on each sheet at a distance equal to the loop radius from the intersection. A known current through this section of electrically small loop produced calculable E and H fields between the sheets in the plane of the loop. These known fields may be used to determine the antenna factor of small E and H antennas placed in the field if the mutual impedance due to the antenna images in the sheets is negligible and the antenna is not close to the open edges of the cell. Measured and calculated antenna factors agree within ±2 dB between 0.25 MHz and 1000 MHz.
The paper describes a simple but unique antenna test facility suitable for aerospace antenna developments. The total idea can be easily adopted by organizations who wish to carry out antenna measurements with minimum required instrumentation. The facility majorly caters for omni and wide beam antenna measurements, has been set up at ISRO Satellite Centre, Bangalore, India. It has been extensively used for omnidirectional antenna developments in VHF, UHF, L, S, and X-bands for India’s various space programs. Radiation pattern, gain, polarization and impedance measurements can be carried out both in near free space conditions as well as the ground reflection modes. The main feature of the facility is the use of large fiber-glass mounting structures for avoiding reflections and perturbations in radiation patterns due to impressed surface currents, specially in VHF ranges. Field probing is done by the use of a fiber-glass X-Y probe positioner. The facility used Scientific Atlanta 1752 Receiver and 1540 Recorder. Suitable software has been added to the facility for contour plotting of radiation levels, calculation of efficiency isotropy, and polarization properties.