In this paper, the design of a graded honeycomb radar absorbing structure (RAS) is presented to realize both a wide bandwidth and absorption over a wide range of angles. For both transverse-electric and transverse-magnetic polarization, a fractional bandwidth of more than 118.6% is achieved for at least a 10 dB reflectivity reduction when the incident angle is <45°, an 8 dB reduction when the incident angle is <55° and a 5 dB reduction when the incident angle is <70°. Meanwhile the 10 dB reduction upper angle limit is approximately 30° for the uniform coating honeycomb RAS in the literature, which loses its absorbing ability when the incident angle is larger than 55°. Furthermore, the total thickness of our design is 10.7 mm, which is only approximately 1.29 times that of the theoretical limitation. The good agreement between the calculated, simulated, and measured results demonstrates the validity of this optimization.

A novel wideband transition from finite ground-conductor backed-CPW (FG-CB-CPW) to microstrip has been demonstrated in 8–23 GHz band. Proposed transition provides a very low-loss alterative to microstrip/coplanar lines at higher frequencies. Simulated results are detailed for both alumina and silicon substrates. Simulated results are validated on alumina substrate providing more than 100% bandwidth with maximum insertion loss of around 1.5 dB in the targeted frequency range. Comparison of the results along with design procedures is detailed in this article.