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Thread
2007-07-04 by Richard Cooke
Hi Folks,
We need some help with a small hand held RF remote controller project.
We're willing to pay for the help. Basically we need some help with
the matching circuit from the nRF905 to a small helical antenna.
If this is an inappropriate post I apologize. I don't know where else
to ask.
Richard Cooke
rcooke@
digitalwavelength
.com
Lake Forest, CA USA2007-07-04 by Jim Wagner
On Wed, 04 Jul 2007 20:27:55 -0000 "Richard Cooke" <rcooke@digitalwavelength.com> wrote: > Hi Folks, > > We need some help with a small hand held RF remote > controller project. > We're willing to pay for the help. Basically we need > some help with > the matching circuit from the nRF905 to a small helical > antenna. > > If this is an inappropriate post I apologize. I don't > know where else > to ask. > > Richard Cooke > rcooke@ > digitalwavelength > .com > Lake Forest, CA USA > Real helicals are sort of tricky. If you mean a helically-shortened dipole (aka "Rubber Ducky"). they are generaly designed to appear as 50 ohms at the connecctor. This allows a standard matchning network to be used. So, the matching network is tailored to what you have or what you want to use. That has to be defined first. Jim Wagner --------------------------------------------------------------- The Think Different Store http://www.thinkdifferentstore.com/ For All Your Mac Gear ---------------------------------------------------------------
2007-07-04 by Jim Wagner
On Wed, 04 Jul 2007 20:27:55 -0000 "Richard Cooke" <rcooke@digitalwavelength.com> wrote: > Hi Folks, > > We need some help with a small hand held RF remote > controller project. > We're willing to pay for the help. Basically we need > some help with > the matching circuit from the nRF905 to a small helical > antenna. > > If this is an inappropriate post I apologize. I don't > know where else > to ask. > > Richard Cooke > rcooke@ > digitalwavelength > .com > Lake Forest, CA USA > It also depends on which band it operates on. Jim --------------------------------------------------------------- The Think Different Store http://www.thinkdifferentstore.com/ For All Your Mac Gear ---------------------------------------------------------------
2007-07-04 by Zack Widup
I never used a nRF905. I'll take a look at the data sheet and see what ideas I get. Zack
On Wed, 4 Jul 2007, Richard Cooke wrote: > Hi Folks, > > We need some help with a small hand held RF remote controller project. > We're willing to pay for the help. Basically we need some help with > the matching circuit from the nRF905 to a small helical antenna. > > If this is an inappropriate post I apologize. I don't know where else > to ask. > > Richard Cooke > rcooke@ > digitalwavelength > .com > Lake Forest, CA USA > >
2007-07-05 by Eric Engler
--- In AVR-Chat@yahoogroups.com, "Jim Wagner" <jim_d_wagner@...> wrote: > Real helicals are sort of tricky. I second the motion! My attempts at making helicals have failed miserably. The winding consistency is critical. And the properties of the core have more effect on the end result than you might expect. Tuning them can be difficult without good test equipment (SWR bridge or antenna analyzer for the frequency involved). A simple dipole will always out-perform a helical. But then almost any antenna will out-perform a helical. Eric, KC8YB
2007-07-05 by Eric Engler
--- In AVR-Chat@yahoogroups.com, Russell Shaw <rjshaw@...> wrote: > > Richard Cooke wrote: > > We need some help with a small hand held RF remote controller project. > > We're willing to pay for the help. Basically we need some help with > > the matching circuit from the nRF905 to a small helical antenna. > At high freqs (2.4GHz etc), RF matching circuits are only reliably done > using simulations that include the pcb taking into account the physical > dimensions of the tracks and component footprints. That's a very true statement. It's almost impossible to match a 2.4 Ghz antenna to a circuit board unless you have a lot of UHF/Microwave experience. Making it work on the bench is one thing, but making it work well for a mass production board is a lot more difficult. I'd definitely recommend that you pay an RF engineer to help you. Eric, KC8YB
2007-07-05 by Russell Shaw
Richard Cooke wrote: > Hi Folks, > > We need some help with a small hand held RF remote controller project. > We're willing to pay for the help. Basically we need some help with > the matching circuit from the nRF905 to a small helical antenna. > > If this is an inappropriate post I apologize. I don't know where else > to ask. At high freqs (2.4GHz etc), RF matching circuits are only reliably done using simulations that include the pcb taking into account the physical dimensions of the tracks and component footprints. I don't have a working one here atm.
2007-07-05 by Jim Wagner
On Thu, 05 Jul 2007 14:35:00 +1000 Russell Shaw <rjshaw@netspace.net.au> wrote: > Richard Cooke wrote: > > Hi Folks, > > > > We need some help with a small hand held RF remote > controller project. > > We're willing to pay for the help. Basically we need > some help with > > the matching circuit from the nRF905 to a small helical > antenna. > > > > If this is an inappropriate post I apologize. I don't > know where else > > to ask. > > At high freqs (2.4GHz etc), RF matching circuits are only > reliably done > using simulations that include the pcb taking into > account the physical > dimensions of the tracks and component footprints. I > don't have a working > one here atm. The nRF905 works at about 430MHz, about 830MHz, and about 915MHz. So, how it is handled depends on which band it operates on. Jim --------------------------------------------------------------- The Think Different Store http://www.thinkdifferentstore.com/ For All Your Mac Gear ---------------------------------------------------------------
2007-07-05 by Leon
----- Original Message -----
From: "Russell Shaw" <rjshaw@netspace.net.au> To: <AVR-Chat@yahoogroups.com> Sent: Thursday, July 05, 2007 5:35 AM Subject: Re: [AVR-Chat] Antenna interfacing help? > Richard Cooke wrote: >> Hi Folks, >> >> We need some help with a small hand held RF remote controller project. >> We're willing to pay for the help. Basically we need some help with >> the matching circuit from the nRF905 to a small helical antenna. >> >> If this is an inappropriate post I apologize. I don't know where else >> to ask. > > At high freqs (2.4GHz etc), RF matching circuits are only reliably done > using simulations that include the pcb taking into account the physical > dimensions of the tracks and component footprints. I don't have a working > one here atm. The nRF905 operates at about 900 MHz. The matching network won't be all that critical. Leon -- Leon Heller Amateur radio call-sign G1HSM Yaesu FT-817ND and FT-857D transceivers Suzuki SV1000S motorcycle leon355@btinternet.com http://www.geocities.com/leon_heller
2007-07-05 by Russell Shaw
Eric Engler wrote: > --- In AVR-Chat@yahoogroups.com, Russell Shaw <rjshaw@...> wrote: >> Richard Cooke wrote: >>> We need some help with a small hand held RF remote controller project. >>> We're willing to pay for the help. Basically we need some help with >>> the matching circuit from the nRF905 to a small helical antenna. > >> At high freqs (2.4GHz etc), RF matching circuits are only reliably done >> using simulations that include the pcb taking into account the physical >> dimensions of the tracks and component footprints. > > That's a very true statement. It's almost impossible to match a 2.4 > Ghz antenna to a circuit board unless you have a lot of UHF/Microwave > experience. Making it work on the bench is one thing, but making it > work well for a mass production board is a lot more difficult. I'd > definitely recommend that you pay an RF engineer to help you. IME (i'm an RF designer), critical layout problems begin kind of around 100-200MHz. Even at 50MHz you have to know what you're doing, but at 500MHz, even if you know everything about what's happening, you still need the numerical analysis of a CAD program to include the distributed pcb layout effects. As long as the soldered-on components and pcb have consistant characteristics, mass production is no problem. Changing brands of components between runs can be a problem.
2007-07-05 by Richard Cooke
I forgot to mention this will be used for the 433MHz band. Sorry about that. Richard Cooke --- In AVR-Chat@yahoogroups.com, "Jim Wagner" <jim_d_wagner@...> wrote:
> > On Wed, 04 Jul 2007 20:27:55 -0000 > "Richard Cooke" <rcooke@...> wrote: > > Hi Folks, > > > > We need some help with a small hand held RF remote > > controller project. > > We're willing to pay for the help. Basically we need > > some help with > > the matching circuit from the nRF905 to a small helical > > antenna. > > > > If this is an inappropriate post I apologize. I don't > > know where else > > to ask. > > > > Richard Cooke > > rcooke@ > > digitalwavelength > > .com > > Lake Forest, CA USA > > > > It also depends on which band it operates on. > > Jim > > --------------------------------------------------------------- > The Think Different Store > http://www.thinkdifferentstore.com/ > For All Your Mac Gear > --------------------------------------------------------------- >
2007-07-05 by Richard Cooke
Eric, What antenna type have you settled on? We'd like to use a very small antenna like those used in after market car alarms. I put a photo of an example antenna on our web site: http://www.digitalwavelength.com/devices/433_MHz_remote_control_example.html I hope this shows what I'm talking about. Thanks, Richard Cooke --- In AVR-Chat@yahoogroups.com, "Eric Engler" <englere.geo@...> wrote:
> > --- In AVR-Chat@yahoogroups.com, "Jim Wagner" <jim_d_wagner@> wrote: > > > Real helicals are sort of tricky. > > I second the motion! My attempts at making helicals have failed > miserably. The winding consistency is critical. And the properties of > the core have more effect on the end result than you might expect. > Tuning them can be difficult without good test equipment (SWR bridge > or antenna analyzer for the frequency involved). > > A simple dipole will always out-perform a helical. But then almost any > antenna will out-perform a helical. > > Eric, KC8YB >