Electromagnetic...

Which of the following statements is/are correct for antenna arrays:

If a dipole Antenna has a radiation resistance of 73 ohm, The loss resistance of 7 ohm and the power gain is 16. Then the directivity is:

The Radiation resistance of a small loop antenna is given by

\({R_{rad}} = \frac{{320{\pi ^4}{S^2}}}{{{\lambda ^4}}}\) , where S = Area = Nπr² (for n turns)

If the radius of the loop is halved, keeping all other parameters same, then the percentage change in radiation resistance is ________%.

A monopole antenna on a large ground plane has a far field pattern function given by

\({F_\theta }\left( {\theta ,\phi } \right) = \left\{ {\begin{array}{*{20}{c}}{A\sin \theta }&{0 \le \theta \le 90^\circ }\\0&{90^\circ \le \theta \le 180^\circ }\end{array}} \right.\) 

The directivity of the antenna (in dB) is _________.

Two communication antennas A and B, one operating at 300 MHz and other at 3 GHz respectively and having the same gain, are illuminated with identical flux density of -100 dBW/m². What is the relation between the received powers (P_A: P_B)?