Suggestion: Have you try another ones for higher gain? See the link for:
Antenna requirements
Three types of integral antenna are recommended and approved for use with the module:
A) Helical Wire coil, connected directly to pin 2, open circuit at other end. This antenna is very
efficient given it’s small size (20mm x 4mm dia.). The helical is a high Q antenna, trim
the wire length or expand the coil for optimum results. The helical de-tunes badly with
proximity to other conductive objects.
B) Loop A loop of PCB track tuned by a fixed or variable capacitor to ground at the 'hot' end and
fed from pin 2 at a point 20% from the ground end. Loops have high immunity to
proximity de-tuning.
C) Whip This is a wire, rod ,PCB track or combination connected directly to pin 2 of the module.
Optimum total length is 16cm (1/4 wave @ 433MHz). Keep the open circuit (hot) end
well away from metal components to prevent serious de-tuning. Whips are ground plane
sensitive and will benefit from internal 1/4 wave earthed radial(s) if the product is small
and plastic cased
A B C
helical loop whip
Ultimate performance ** * ***
Easy of design set-up ** * ***
Size *** ** *
Immunity proximity effects ** *** *
Range open ground to similar antenna 200m
