A simple wire counterpoise will improve those antennas a fair bit. Much depends on things that you can't easily change, the encoding scheme an= d quality of the decode software.=20 Amplifiers are illegal on the transmit side, and frequently don't do any go= od on the receive side at improving the signal to noise ratio. Besides, yelling louder is not always the best answer. :) A reflector a quarter wave behind the antenna can be used to shape the gain= pattern. Three sides of a box covered in foil can become a corner reflect= or. There are a few options. "Earthing" anything at this frequency is a practical impossibility. A conne= ction to the coax shield is all you can really do, and reflectors and direc= tors happily do their jobs without any connection to "ground". -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of= rubenjonsson@bredband.net Sent: Thursday, August 4, 2016 8:39 AM To: Microcontroller discussion list - Public. Subject: Re: [EE] Any good tips/ideas on increasing 433Mhz comms range? As long as the box is large enough (not sure about the numbers but I think = it should be extending at least 1/4 wavelength on both sides of the antenna= with the antenna perpendicular to it), it can be used as the ground plane. It should be connected to the ground part of the connector for the whip ant= enna at the antenna side. The metal box should not be connected to anything= except the antenna ground at the antenna side. If the metal box needs to be earthed, I don't think that should be a proble= m. /Ruben On Thu, 4 Aug 2016 10:13:24 -0400, Neil wrote: > By "ground-plane", do you mean the mesh wire network? FWIW, the case=20 > is metal and the antenna still just hangs outside the box. Can I use=20 > the metal box for any part of this ground plane? > BTW, the unit/case is not grounded to earth... I'm using a 2-wire DC=20 > wall wart to power the box. And on the PC side, power is provided by=20 > a USB-to-serial converter. >=20 > Cheers, > -Neil. >=20 >=20 >=20 > On 8/4/2016 6:35 AM, rubenjonsson@bredband.net wrote: >> Second that. You should be using a "counterpoise" (ground plane or >> rods) with a 1/4 wave whip antenna to get correct impedance match and=20 >> optimum performance. A whip antenna is actually only half of the=20 >> antenna. >> >> /Ruben >> >> On Wed, 3 Aug 2016 23:06:49 -0600, David VanHorn=20 >> >> wrote: >>> Quarter wave and counterpoise? With antennas "short" generally equates >>> with "sucks". I have seen a counterpoise add 6db even to a helical >>> "ducky". >>> >>> On Aug 3, 2016 10:58 PM, "Neil" wrote: >>> >>>> Hi all, >>>> >>>> I built a quick device for a friend that lets a receptionist send=20 >>>> messages from a PC to a desktop display device, and vice-versa with=20 >>>> a handful of canned responses. The PC side uses VB to serial (via=20 >>>> USB), to a USB-to-serial interface, then a 433 Mhz serial module,=20 >>>> through an IPEX-to-RP-SMA interface, to a short whip antenna. The=20 >>>> desktop display device also has the same 433 Mhz serial module=20 >>>> (controlled by an Arduino), to the same IPEX-to-RP-SMA interface=20 >>>> cable, then to an identical whip antenna. >>>> >>>> I'm not getting the range necessary... I'm getting 35-ish feet=20 >>>> indoors (through one wall), and need about 100 feet indoors (in an=20 >>>> office through a glass wall). I've tried a 433 Mhz PCB antenna,=20 >>>> but that got me less distance than the whip antennas. And the whip=20 >>>> antennas are listed as being for 433 Mhz. >>>> >>>> Any clues on how to get better distance? I'm looking for 433Mhz=20 >>>> amplifiers, but they're a bit pricey. I'm short on time, so hoping=20 >>>> to find a ready-made solution (if an amp is necessary), rather than=20 >>>> having to build one. >>>> >>>> Cheers, >>>> -Neil. >>>> >>>> >>>> -- >>>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20 >>>> View/change your membership options at=20 >>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>> -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t --=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 .