A waveguide comprising first and second waveguide sections, each waveguide section comprising a main body portion (12) and a connecting portion (14) at its distal end, said first and second waveguide sections being longitudinally aligned to define a conduit therethrough with a butted interface (28) therebetween, the connecting portion of each waveguide section having: (i) a first circumferential ridge (16) on its outer surface located adjacent its distal end, (ii) a second circumferential ridge (18) on its outer surface spaced apart from the first circumferential ridge, and (iii) a third circumferential ridge (20) on its outer surface located between said first and second circumferential ridges, such that a first respective recess (19) is defined between said second and third circumferential ridges and a second respective recess (17) is defined between said first and third circumferential ridges; the waveguide further comprising a sleeve member (22) over said butted interface (28), such that a respective first cavity (19a) is defined between an inner surface of said sleeve member (22) and each said first recess (19) and a respective second cavity is defined between the inner surface of said sleeve member (22) and each said second recess (17), each said first cavity (19a) having a chemical adhesive therein operative to join said first and second waveguide sections together by means of said sleeve member (22).