The measured characteristics of slots in a transmission line propagating the TEM mode are given in Part I. The line consists of a rectangular outer conductor and a round inner conductor. A comparison is made between measured and theoretical results. The characteristics of dumbbell-loaded slots are shown. The results are also presented for a linear array which was designed using the dumbbell-loaded slots. In Part II the investigations were carried out in a line consisting of a rectangular outer conductor and a flat center conductor. Effects of different types of loading on resonant length and resonant frequency were investigated. The bandwidth of transverse slots as a function of shape and loading was studied and a comparison for various slot configuration is given.