wireless sensor

:slight_smile: goodevening guys :slight_smile: can you give me an advice about the sensor iā€™m going to use?
what will be the best omni directional sensor with 10 meter range?
once they go beyond to the 10 meter, it will give an automatically alarm.

Does it have to be a circle or would a triangle or square work? What obstacles do you have to work around? What environmental conditions? How precise does this need to be? How reactive? How will the alarm turn off? What is your project? Why don't you give more detail?