N-Way Parabolic UWB Planar Spatial Power Divider/Combiner

In this article, a 1-to-N parabolic ultrawideband (UWB) planar spatial power divider/combiner is designed and implemented. In this structure, the signal from one port (port 1) passes through a parabolic-shaped transmission line to N parallel ports (ports <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2~\rightarrow ~N +1$ </tex-math></inline-formula>), which are positioned in a straight line at equal distances from each other. Due to diffraction, the traveling wave from port 1 will be cylindrical, and this parabolic-shaped transmission line converts the cylindrical wave into a plane wave at the N parallel ports. To accurately evaluate the performance of the divider/combiner, a new method is proposed by defining a parameter called <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{\mathrm { error}}$ </tex-math></inline-formula>. The simulated results obtained for a 1-to-4 divider/combiner within the frequency range of 15–60 GHz [120% bandwidth (BW)] indicate that the amplitude difference between ports is less than 2.4 dB, and the phase difference is less than 8°. To further enhance the amplitude and phase balancing, the shape of the transmission line, responsible for converting the cylindrical wave to a plane wave, is optimized using the particle swarm optimization (PSO) algorithm and simulation by MATLAB-HFSS API. The optimized results for a 1-to-4 divider/combiner within the frequency range of 15–60 GHz demonstrate an amplitude difference of less than 0.75 dB between the ports and a phase difference of less than 2.5°.