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This paper presents a thin absorbing structure comprising an array of finitely conductive terminal-loaded dipoles spaced about half a wavelength apart and located above a ground plane. We show that if the antennas are terminated with proper load impedance, instead of a conjugate-matched one, a perfect absorption can be attained even when the array lies close to the ground plane. We also identify a threshold height below which the absorption efficiency rapidly drops and perfect absorption cannot be realized. The idea is illustrated via a concrete example of array of dipoles printed with conductive ink technology on a Kapton HN flexible film backed by a rigid Rogers 4350B substrate. The array is designed for perfect absorption at 3.45 GHz when it is located one-tenth of a wavelength above the ground plane. Good agreement between simulation and measurement results is demonstrated. [ABSTRACT FROM AUTHOR]

Approximate analytical expression is presented for calculating the current flowing along a lossy finite-length dipole antenna illuminated by an obliquely incident plane wave. This current is used to evaluate the total power absorbed, both by the lumped load connected across the antenna terminals and by the lossy material of which the antenna structure is made. An approximate value of the load impedance that maximizes the total absorbed power is then derived. The results are compared against results obtained using a method of moments solution and good agreement is found. [ABSTRACT FROM PUBLISHER]

Bolometer antennas are required to have not only a large gain–bandwidth product but also a fast heating rate suitable for video rate operation. However, while the gain–bandwidth product of an antenna increases with the fraction of the antenna bulk volume occupied by its enclosing sphere, its heating rate decreases. In this paper, we show that for a typical heating rate requirement, wire antennas such as dipole and bow-tie antennas are preferable over planar antennas such as triangular and pentagonal antennas. More complex bent-wire antenna geometries achieved by a genetic algorithm are shown to yield better performance. [ABSTRACT FROM PUBLISHER]