Effect of phasing-sector angular extent in FM reticles

A technique is presented for increasing the useful power of the FM modulation signal from a spinning FM reticle with a phasing sector. Spinning FM reticles often determine a target location by using a combination of a phasing sector to establish the angular target location and a radial frequency variation to establish the radial target location. Typically, the phasing sector of this reticle type consists of a semicircular transmissive sector with the other semicircular sector which provides FM modulation. The power of the FM modulation signal is increased by matching the phased-sector geometry to the size that corresponds to the period of the modulation frequency. This type of reticle is compared and contrasted with the more typical semicircular phasing-sector reticle in both the time and frequency domains.