By Marcus C. Walden
Abstract: A lightweight, wideband tapered-slot antenna that uses an antipodal Vivaldi design and provides useable gain from ~5 GHz to in excess of 50 GHz is described. Simulations and measurements are presented that show excellent agreement. This antenna design is currently deployed in handheld test equipment.
I. INTRODUCTION: Numerous designs exist for wideband (multi-octave) antennas that also have good directivity. However, the selection pool reduces if the antenna is to be employed within handheld test and/or monitoring equipment. For example, the relative bulk and weight of standard gain or double-ridged waveguide horns is undesirable, as is their cost.
Microstrip antennas are attractive because they are, by comparison, lightweight and cheap. While a patch array is simple, its feed structure is more complicated and incurs losses, particularly at higher microwave frequencies. For desired operation from below ~20 GHz to above ~40 GHz, a tapered-slot or Vivaldi antenna was considered suitable . Furthermore, an antipodal Vivaldi design was selected because it offers a simple microstrip-coax interface and provides good gain over a wide bandwidth .
Inevitably, some engineering design trade-offs are required.