This paper presents the experience in designing LTCC antennas operated in F-band (90–140 GHz). A few examined structures are presented and their electrical parameters dependencies on LTCC technology limitations are shown. The paper is focused on two main aspects: the first one is related to the quality of multi-layered structures and the second one to the properties of metallization, which has a big influence on electrical parameters of designed structures. An effect of material shrinkage is also investigated. Additionally, possibility of creating air cavities to lower the effective permittivity of the substrate material is considered.