Frequency scanned antenna array using a suspended stripline negative index transmission line

In suspended stripline, series capacitors can easily be realized by overlapping strips on opposite sides of the substrate, and shunt inductances by thin strips to ground, increased with some amount of inset. In this way, negative index or left-handed transmission lines can be realized. Such a structure then is used as a feeding line for an antenna array which can be frequency-scanned from end fire to backfire over a wide range of angles. A first antenna array based on this principle with six dipole antennas was designed and tested successfully. Following this and using a different point of view on this type of antenna, an improved scanning antenna is designed using band-pass filter type in this technique, resulting in a scanning range from -60° to +60°.