Several ferrite devices recently developed for systems applications are described. The behaviour and characteristics of extremely compact u.h.f. isolators based on new microwave techniques are reported. Faraday rotation and Y-circulators operating over wide temperature ranges and with broad frequency bandwidths are described. Also included are switches based on Faraday rotation, turnstile-junction and stripline-junction circulators. Strip and rectangular coaxial transmission-line phase shifters particularly suitable for antenna scanning applications are discussed. A discussion in terms of the intrinsic properties of ferrite materials is given that defines the frequency regions of operation for these phase shifters.