RFM69HW Range issue

[virus]

Hello, I am using RFM69HW transceiver module for a pulse transmission between a two devices. Both have same module ie RFM69HW.
Operating freq.   : 868 MHz
Bit Rate             : 300 KBPS
Modulation Type : FSK
Mode                 : Continuous Mode
Transmitting Power set to +20dBm.

I am transmitting a 30Hz pulse with 300uS ON period through DIO2 pin. Both devices are enclosed in plastic casing but antenna is connected to both devices and it is attached outside of the casing. Antenna used is helical type and have gain of 2dBi.

My issue is whenever I test this setup in my office, I get proper result ie Receiver can receive the transmitted pulse. But its range is no longer than 10 meters. Also when tested outdoor environment, signal is not received.

What can be issue ?
Frequency ?
Antenna ? If it is antenna, then what should be the gain of antenna ?
Or any other ?

[Felix]

Assuming your code setup is bullet proof - is the hardware on a proper PCB or whipped up with breadboards and loose wires?
Helical will need a ground plane since it's basically a monopole. You'd be better off using a dipole such as this if you want to take it outside your PCB/enclosure.

[virus]

Hi Felix, Thank you for your response.
Hardware has proper designed PCB, not breadboard and loose wires.
I will get one dipole antenna and will test with it.
In case of helical antenna, should I connect ground of PCB to shield of co-axial cable of antenna or is there any other way for it?

[Felix]

Yes you will need a ground plane at the base of your monopole helical.
See this page for some visuals and explanation:

https://lowpowerlab.com/guide/rf-best-practices/quarter-wave-vertical/