The inverter 74AL SO4 has the following specifications:
$${I_{OH}}{\,_{\max \,}} = \, - $$ 0.4mA, $${I_{OL}}$$ max = 8mA, $${I_{IH}}$$ max = $$\mu $$A , $${I_{IL\,}}_{\max \,}$$=0.1mA. The fan out based on the above will be

A transmission line of 50$$\Omega $$ characteristic impedance is terminated with a 100 $$\Omega $$ resistance. The minimum impedance measured on the line is equal to

A parabolic dish antenna has a conical beam 2⁰ wide. The directivity of the antenna is approximately

A rectangular air-filled waveguide has a cross section of $$4\,cm\,\, \times \,\,10cm$$. The minimum frequency which can propagate in the waveguide is