|
In recent years, much work has been done on quasi-optical components that interact directly with waves propagating in free-space without need for a separate receiving antenna, [1-5]. By embedding different devices in a periodic planar array, processing such as filtering, amplification [5], phase shifting [2], and mixing [4] may be performed on an incident wave. The advantages of such an approach are many. At millimeter-wave frequencies, the dimensions of waveguides become quite small and the losses associated with the skin effect become severe. Furthermore, solid-state components have relatively low power-handling capabilities. Planar grids of solid-state devices overcome these deficiencies by distributing the energy over an array of devices. In addition, the losses associated with metal waveguide walls are eliminated. Tuning can be accomplished using mirrors and dielectric slabs. The structure of the grids is compatible with modern IC fabrication techniques which lends the approach conveniently to scaling down to shorter wavelengths. A complete system using quasi-optical grids can be realized by simply cascading the grids one-after-another to form a receiver or a transmitter. The basic components that make up a heterodyne receiver are a local oscillator, amplifier, and mixer. Typically, a signal is received first by an antenna and fed to a waveguide or transmission-line circuit. The signal is then amplified and down converted to an IF frequency. In this paper we present designs and results for a grid oscillator, mixer, and amplifier that could be used to build a quasi-optical millimeter-wave heterodyne receiver.
|
