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Antennas or aerials
Published in Geoff Lewis, Communications Technology Handbook, 2013
Declination angle. The additional angular offset to the inclination angle of a polar mount system required to ensure that a parabolic reflector antenna can accurately track satellites in the geostationary orbit.
Design of tracking system for helical-coiled receiver tube of parabolic trough collector
Published in International Journal of Ambient Energy, 2018
G. Mageshwaran, S. Ramachandran, K. Gobinath, R. B. DuraiRaj
We have a choice of five different solar tracking modes: Mode 1: The solar collector is rotated about an east–west axis horizontally with one adjustment daily such that the solar direct radiation is normal to the collector aperture plane at solar noon.In this mode of tracking, the aperture plane is a hypothetical plane with γ = 0. At solar noon ω = 0 slope can be found by setting θ = 0.Therefore cos θ = cos2δ cos ω + sin2δ.Mode 2: The rotation of plane is about an east–west axis horizontally similar to mode 1 with an exception of continuous adjustment to minimise the angle of incidence.Aperture plane is facing south the condition for θ to be the minimum is that the first derivative should be equated to zero and the second derivative should be positive, therefore RHS is differentiated with respect to β (variable) and equating to zero, it follows, cos θ = (1− cos2δ sin2ω)1/2.Mode 3: The third mode has got north–south axis of rotation horizontally with continuous adjustment to minimise the angle of incidence similar to mode 2.The surface azimuthal angle is –90° at forenoon and +90° at afternoon Mode 4: The plane of rotation is north–south axis which is parallel to the earth’s axis with continuous adjustment.The focal axis is north–south and when inclined at an angle equal to the latitude, the axis is parallel to the earth’s axis (Figure 2).This orientation is referred to as polar mount Mode 5: Two-axis tracking surface is continuously oriented to face the sun at all times