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=20 whip antenna 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 problem. /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 is= =20 > metal and the antenna still just hangs outside the box. Can I use the=20 > 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 a=20 > 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 >> optimum performance. A whip antenna is actually only half of the >> antenna. >> >> /Ruben >> >> On Wed, 3 Aug 2016 23:06:49 -0600, David VanHorn >> 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 >>>> messages from a PC to a desktop display device, and vice-versa with a >>>> handful of canned responses. The PC side uses VB to serial (via USB), >>>> to a USB-to-serial interface, then a 433 Mhz serial module, through an >>>> IPEX-to-RP-SMA interface, to a short whip antenna. The desktop displa= y >>>> device also has the same 433 Mhz serial module (controlled by an >>>> Arduino), to the same IPEX-to-RP-SMA interface cable, then to an >>>> identical whip antenna. >>>> >>>> I'm not getting the range necessary... I'm getting 35-ish feet indoors >>>> (through one wall), and need about 100 feet indoors (in an office >>>> through a glass wall). I've tried a 433 Mhz PCB antenna, but that got >>>> me less distance than the whip antennas. And the whip antennas are >>>> listed as being for 433 Mhz. >>>> >>>> Any clues on how to get better distance? I'm looking for 433Mhz >>>> amplifiers, but they're a bit pricey. I'm short on time, so hoping to >>>> find a ready-made solution (if an amp is necessary), rather than havin= g >>>> to build one. >>>> >>>> Cheers, >>>> -Neil. >>>> >>>> >>>> -- >>>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >>>> View/change your membership options at >>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>> --=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 .