Beam Splitting Elements Research Articles

Millimeter-wave holographic power splitting/combining

It is shown that holography offers a novel solution to the problem of millimeter-wave power splitting and combining. With the help of an approximate model, we demonstrate that a hologram will work as a beam-splitting element, provided that it records the holographic image of the beams to be generated. To verify this observation, a beam splitter consisting of a hologram and an antenna array is analyzed by means of a rigorous network model. This analysis serves to find the optimum structure of the beam splitter. Measurements on a realized prototype of the beam splitter prove the possibility of achieving a high splitting efficiency, a high inter-element isolation, and a relatively large bandwidth. Flexibility in the orientation and the number of outputs is another outstanding feature of this holographic approach.

The Use of an Improved Diffraction Grating Interferometer

A conventional schlieren system was converted into a Kraushaar interferometer by the addition of matched diffraction gratings as the beam splitting and recombination elements. Optical quality of the added features of this installation were shown to be not a limiting factor, but the optical platform must be isolated well for good results. Basic optical theory applicable to this device is summarized. Several aspects are indicated which enhance the fringe or image quality. This device has been used to find the surface pressures and flow field structure around some simple two-dimensional airfoil shapes. Comparison of these results with calculations indicates good agreement between the diffraction grating interferometer data and analytical data.