A person with a receiver is 5 Km away from the transmitter. What is the distance that this person must move further to detect a 3-dB decrease in signal strength?

In a uniform linear array, four isotropic radiating elements are spaced $$\lambda /4$$ apart. The progressive phase shift between the elements required for forming the main beam at 60° off the end-fire is

A medium wave radio transmitter operating at a wavelength of 492 m has a tower antenna of height 124m. What is the radiation resistance of the antenna?

For an 8 feet (2.4 m) parabolic disk antenna operating at 4 GHz, the minimum distance required for far field measurement is closest to