Well the antenna is made in such a way that the groundplane is simulated 6 feet below the tip of the antenna. ---------- > From: Sean Breheny > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [OT] Wireless RF Modules > Date: Friday, March 06, 1998 8:14 PM > > > At 03:13 PM 3/6/98 -0600, you wrote: > >I believe the unliciensed 900MHz band is restricted to 30mW xmitter output > >in the USA. The actual frequency is also important, i.e. 915MHz. With a > >3db antenna and line-of-sight you should be good for 1 mile. Remember > >antenna placement, to escape ground effects it needs to be about 35 feet up. > > > > 35 feet??! I'm not an expert on RF, but I do seem to remember that the > general rule of thumb for antennas is that the separation between them and > the ground should be some multiple of their wavelength, and for the 146 MHz > band, 6 feet is usually considered enough(if I remember correctly), so I > would hardly think that the minimum distance for 900MHz would be greater! I > could be wrong, just curious as to where 35 feet came from. > > Sean > > +--------------------------------+ > | Sean Breheny | > | Amateur Radio Callsign: KA3YXM | > | Electrical Engineering Student | > +--------------------------------+ > Fight injustice, please look at > http://homepages.enterprise.net/toolan/joanandrews/ > > Personal page: http://www.people.cornell.edu/pages/shb7 > mailto:shb7@cornell.edu > Phone(USA): (607) 253-0315