> Therefore I considered replacement of the antenna.
> The original PCB microstrip antenna probably does not provide
> the best radiation pattern,but it should be quite easy to replace it with
> a quarter wave dipole.
> It should be enough to peel off the microstrip antenna from the PCB
> leaving only the "RFin" strip (see
> http://www.hoperf.com/upfile/RF70.pdf , page 22),
> and then solder the 37mm straight wire to it.
> Does it make any sense? Can it improve the link quality?

I now sell these modules so I made some experiments. A line-of-sight=20
distance of 50 .. 100 m seems possible, but within a (stone brick)=20
building even 10 m can fail. I did these experiments at one channel and=20
with a WIFI node nearby, so YMMV.

I tried a straight wire (cut the start of the PCB wiggle, soldered a 37=20
mm wire to the inner corner). The results were bad: line-of-sight=20
distance between two such modules (both antenna wires vertically) was=20
only ~ 10 m.

IME the power setting of the modules has very little influence on the=20
possible distance.

I sort-of translated the HopeRF example code to C for my DB038 board=20
(HiTech C) and to C for an LPC2148 board (GCC). I'll try a Jal port=20
next. I'll probably try a tin-can directional antenna too, might make a=20
nice short-range foxhunt system.

--=20

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu

--=20
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