It has long been known that a slender radome may be generated aerodynamically by projecting a thin spike ahead of a blunt-nosed vehicle. This report is concerned with the effects of such a spike on the performance of a tracking radar, in particular with the induced transmission losses and boresight errors. In order to investigate these effects a series of tests were performed on a spike assembly at the Johns Hopkins University Applied Physics Laboratory. The test equipment included a c.w. radar transmitter emitting in a linearly polarized mode and a phase comparison monopulse receiving system for both C and X band frequencies. The parameters investigated included various spike geometries and spike sizes, relative alignment of polarization vector with respect to spike linkage, the effect of spatial orientation of spike position and spikeradome interaction. The results of the tests showed that, by properly optimizing the conditions, the combination of a properly designed physical spike and hemispherical radome can perform at least as well as state-of-the-art streamlined radomes.