Fine structures in the F and D regions of the ionosphere at a high-latitude site are compared using the EISCAT incoherent-scatter radar at Svalbard. They are found to occur at almost the same time and to show significant co-variation in relative magnitude. These structures are not seen in the E region. Inversion of the D-region electron-density profiles provided an estimate of the incident electron spectrum. It is suggested that the quasi-periodic structuring of the lower D-region is due to modulation of the electron spectrum by the energisation of electrons of 50-70 keV up to 80-100 keV by wave-particle interaction in the F-region.