Figure 2

The impact of the bias line on the performance of the Yagi-Uda arrays used in the proposed angle-sensing detector and the radiation patterns of one of the Yagi-Uda arrays in the two-element angle-sensing detector. (a) The input impedance of the DC bias line (acting as an IR transmission line) as a function of its length. Three examples are shown where the transmission line is terminated with 50 Ω, open, and short. The input impedance converges to the constant impedance of 265–18.5j Ω as the length is increased. This is the characteristic impedance of the DC bias line at the operating frequency of 28.3 THz (λ = 10.6 μm). The dots on each curve correspond to the length of 30 μm. (b) The absorbed power in the bolometer (driven element) of a single Yagi-Uda array when the antenna is illuminated with an IR wave arriving from θ = 45° for three different situations: (1) The antenna in isolation (no bias line). (2) The DC bias lines are directly connected to the antenna. (3) The DC bias lines are connected to the antenna with an in-line, low-pass IR filter. In all of these simulations, the length of the driven element was optimized to maximize the received power at the frequency of 28.3 THz, when the incident wave comes from the angle of θ = 45°. (c) The radiation patterns of one of the Yagi-Uda antenna arrays in the optimized IR detector. The radiation is maximized around θ = 45°, and its intensity reduces by more than 10 dB for negative incidence angles where the reflector reflects the radiated field.