There is described a wearable respiration sensor generally having a stretchable substrate to be worn around a user's torso; and a dipole antenna having two flexible conductive elements extending in opposite directions from a center, relative to a dipole axis, and being secured to the stretchable substrate, each of the two flexible conductive elements having a proximate end near the center, a distal end away from the center, and a curved portion curving away from and back towards the dipole axis between the proximate end and the distal end, the two flexible conductive elements being in a point reflection symmetry relative to one another relative to said center in a manner that, when the stretchable substrate is stretched along the dipole axis, the curved portions of the two flexible conductive elements are flattened and the distal ends are moved away from one another.