  A dispersive delay structure (DDS) is a device that creates a specified group
delay function over frequency bandwidth. In this paper, the idea of trapping
the electromagnetic waves in a feedback loop is proposed to achieve higher
group delay swing. The proposed structure includes two transmission lines and
two junctions that act as power divider/combiner. The transmission lines can be
either dispersive or non-dispersive. The group delay in the proposed
configuration is proportional to the injected power into the feedback loop. So,
an increase in the group delay swing can be done by improving the junctions or
by adding more feedback loops to the structure. Based on this configuration, a
novel DDS, using the substrate integrated waveguide (SIW) transmission line, is
introduced. According to the experimental results, the proposed device with a
relatively compact size creates high group delay swings (9 ns), and its
insertion loss is about 7 dB.
