Showing papers on "L band published in 1987"

L-band phased array antennas for mobile satellite communications

Abstract: The planar phased array, due to its low profile and beam agility, has been proposed as one of the land vehicle antennas for the U.S. Mobile Satellite Experiment (MSAT-X) program. The objective is to develop medium gain satellite tracking antennas (as versus omni low gain antennas) that will alleviate the spacecraft power burden through higher gain, and enable multiple-satellite operation in the same frequency band through narrower beam. In addition, this narrower beam can spatially filter out a significant portion of the undesired multipath component. The major challenges are to seek technologies that will minimize the antenna insertion loss, achieve accurate beam pointing with sufficient inter-satellite isolation, and minimize the antenna production cost.

Frequency Stability of L-Band, Two-Port Dielectric Resonator Oscillators

Abstract: Dielectric resonator oscillators operating at 1.5 and 2.0 GHz, based on a two-port resonator design incorporated into a basic feedback oscillator configuration were evaluated and show state-of-the-art, close-to-carrier phase noise performance. Typically, at 1 KHz carrier offset frequency the single sideband phase noise levels were -130 dBc/Hz and -120 dBc/Hz for the 1.5 GHz and 2.0 GHz oscillators, respectively. Vibration sensitivity was also investigated and the resonators show fractional frequency changes per g in the range of 10/sup -7/ to 10/sup -9/ for the 1.5 GHz and 2.0 GHz designs, respectively.