Lens AntennasMay 10th Fact-of-the-Day
Radio-frequency lenses can be used to focus radio waves as optical lenses are used to focus light waves. In fact, Yagi antenna director elements function as crude lenses to focus energy from a large capture area on a receiving dipole that has a smaller capture area or to focus energy spreading from a radiating dipole into a beam. More effective lenses that look and work more like optical lenses are practical at microwave frequencies. For example, dielectric material such as polystyrene can be machined or molded into a lens that will delay RF energy passing through its thicker center, relative to RF energy that passes through its thinner edges, and cause RF energy to focus on a target. Other examples include H-plane metal-plate lenses that delay RF energy passing through their center relative to through their edges and E-plane metal-plate lenses that shorten RF path lengths through their edges relative to through their center. ©2005 Martek, International. All rights reserved.
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