The phase velocity for the $$T{E_{10}}$$ mode in an air-filled rectangular waveguide is

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?

Consider a linear array of two half - wave dipoles A and B as shown in Fig. The dipoles are $${\lambda \over 4}$$ apart and are excited in such a way that the current on element B lags that on element A by $${90^0}$$ in phase

(a) Obtain the expression for the radiation pattern for E in the XY plane, i.e.,$$\left( {\theta = {{90}^0}} \right)$$.
(b) Sketch the radiation pattern obtained in (a).

The line-of-sight communication requires the transmit and receive antennas to face each other. If the transmit antenna is vertically polarized for best reception the receiver antenna should be