??? -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Richard Fry Sent: Friday, September 27, 2013 7:27 PM To: topband@contesting.com Subject: Topband: 5/8 wavelength vertical is mo betta than shorter versions??
Niko AC6DD wrote: >... the 5/8 Vertical idea came from the "All About Vertical Antennas" Book. >Getting 3dB with some wire and a balloon sounded pretty good. ____________ The approximate 3 dB improvement of the radiated field of a 5/8-wave monopole compared to a 1/4-wave monopole refer only to the maximum fields they radiate, NOT to the fields they radiate at __all__ elevation angles. Those maximum fields always occur in the horizontal plane, regardless of the vertical monopole radiator length/height, and/or the conductivity of the earth within a 1/2-wavelength radius from the base of that monopole. This may be confirmed by referring back to the FCC document linked earlier in this thread ( http://s20.postimg.org/olcquv94d/Monopole_Elev_Patterns.gif ). For 1 kW of applied power, the groundwave field radiated by a perfect 1/4-wave radiator over a perfect ground plane is about 195 mV/m. For those conditions using a 5/8-wave radiator, the field at 1 mile is about 275 mV/m. Other things equal, this field improvement in the horizontal plane for a 5/8-wave vertical monopole relative to a 1/4-wave vertical monopole is very close to 3 dB. RF _________________ Topband Reflector _________________ Topband Reflector