I was thinking of lower, only because I know I'll get better range and=20 less issues with it. Now that it seems I can use 433Mhz in the US, I'll=20 prob go with that. And if the receivers are the stationary parts, then antenna size is no=20 issue. Cheers, -Neil On 10/7/2019 2:59 PM, David Van Horn wrote: > Think of the wavelength. An inch movement is huge in terms of relative p= hase at 2GHz. At 457kHz the wavelength is about 656m and an inch gives you= no measurable phase difference. There's a new ham band nearby, where I t= hink they've already set the biggest distance record you can without leavin= g earth. > > Many more things are reflectors and absorbers up high. Down in the 100's= of kHz, reflectors are usually microscopic in terms of wavelength, and alm= ost nothing attenuates the signal. Ferrite absorbing blocks as used in EMI= chambers do almost nothing. Copper mesh works pretty well. > > What frequency were you thinking of using? > > -- > David VanHorn > Lead Hardware Engineer > > Backcountry Access, Inc. > 2820 Wilderness Pl, Unit H > Boulder, CO 80301 USA > phone: 303-417-1345 x110 > email: david.vanhorn@backcountryaccess.com > > -----Original Message----- > From: piclist-bounces@mit.edu On Behalf Of Neil > Sent: Monday, October 7, 2019 12:42 PM > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Locating object position by radio > > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .