[Antennas] W3EDP and mobile antennas

[Tom Bates]

>> For example: an antenna only 8 feet tall
operated on 80 meters will have a radiation resistance of only 1 Ohm!

Hello Harvey...  I understand this concept.  But, how is this radiation resistance
calculated ( 8 ft, 80M, 1 ohm ) ?    Does doubling the antenna length to 16 feet make
it 2 Ohms ?  And, does a cap hat on the same 8 ft antenna also raise radiation
resistance by some factor ?

Thanks for all your fine input on the antennas sig.

    73,   Tom   AA1NZ