The quick answer:
any accelerated charge will produce an electromagnetic wave. Antennas are structures of metal that form currents on them that radiate with phase relationships that produce radiation field patterns.
easy starter book: Antennas by Krause
If indeed you mean "enhance", generally, the answer is no. THe best radio reception you can get is point to point with no obstructions in between (including so-called free space). Thus, if a buidling is in the line of sight of the two antennas, then it will interfre with the radio...
a source of the allocated frequencies:
http://www.fcc.gov/oet/spectrum/table/fcctable.pdf
Otherwise, you obviously need a TX, antenna system and RX. ITs useful to know the purpose, but for microwave equipmen, do an internet search on "microwave compnonents", e.g. Watkins Johnson is an...
