An astronomical radio telescope consists of two antennas separated by a distance
ID: 2046664 • Letter: A
Question
An astronomical radio telescope consists of two antennas separated by a distance of 210 m. Both antennas are tuned to the frequency of 18 MHz. The signals from each antenna are fed into a common amplifier, but one signal first passes through a phase selector that delays its phase by a chosen amount so that the telescope can "look" in different directions. When the phase delay is zero, plane radio waves that are incident vertically on the antennas produce signals that add constructively at the amplifier. What should the phase delay be so that signals coming from an angle = 11° with the vertical (in the plane formed by the vertical and the line joining the antennas) will add constructively at the amplifier? Hint: Radio waves travel at 3.00 108 m/s.
_______ rad
Explanation / Answer
= 3 * 10^8 / 18 * 10^6 = 16.66 m wavelength of incoming signal, 18/ 16.66= 1.08 The phase difference is then 360 * 1.08 = 388.9 degRelated Questions
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