Home |
Search |
Today's Posts |
#12
|
|||
|
|||
Serge, ON4BAA wrote:
"What about using an inverted 1/4wave groundplane in order to avoid ground losses?" How high above the earth can the inverted ground plane be placed? Brown, of the famous RCA trio of Brown, Lewis. and Epstein, invented the groundplane antenna. B,L,& E did most of the work on broadcast ground systems when broadcasting was new. Brown described the purpose of elevated radials as capture of the antenna current which otherwise might include the earth which could impose exorbitant loss. The energy fed to a groundplane produces capacitive (displacement) current between the vertical radiator and its return paths, be they radials, other antenna element(s), or the earth. If you place the groundplane upside down, you lose the screen between the radiator and the earth, which it hides from the radiator. If the groundplane is very high, capacitance between the radiator and the earth will be very small. Likewise, current between the radiator and the earth will be very small. So, the question of how high can the groundplane antenna be elevated is not entirely facetious. Loss is likely lower in the rightside up groundplane Best regards, Richard Harrison, KB5WZI |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
EH antenna, FCC certification is arrived | Antenna | |||
Ten-tec vee beam | Antenna | |||
FA: ANLI RD-88H ANTENNA SCANNER HAM DUAL BAND *** Ends Today!!! | Antenna | |||
50 Ohms "Real Resistive" impedance a Misnomer? | Antenna |