Suspended Substrate Stripline
Suspended Substrate Stripline (SSS) is traditionally a printed circuit technology that can be used for both broadband and narrowband filters; typical frequency range 500MHz to 26GHz.
The wide range of realizable impedance values makes this medium particularly suitable for high pass and low pass filters that can be cascaded together to form broadband band pass filters and multiplexers.
Generalised Chebychev filter prototype designs result in highly selective band edges with low passband loss and high stopband attenuation.
As suspended substrate is a printed technology it exhibits very repeatable performance, and devices can be made with very tight amplitude and phase tracking.
For some higher power applications, rather than use a substrate, solid metal bars are suspended in air forming low PIM filter structures.