A Compact and Broadband Four-Way Dual Polarization Waveguide Power Divider for Antenna Arrays

The design and optimization of a novel compact and highly efficient power divider exhibiting dual-polarization in an in-phase $2 \times 4$ scheme (4-way) is presented. The two fundamental orthogonal modes $TE _{10}$ and $TE _{01}$ arrive in-phase on each of the four square waveguides for each polarization by the utilization of four 3-port turnstile junctions accompanied by four E-plane and two H-plane power division structures. The power divider ends up to two commercial waveguide (WR75) ports (each for one polarization). The presented passive component can be used as a dual-polarized feeding network for a $2 \times 2$ antenna array or any four-port radiating element with square input waveguides and aperture sizes above $2.4 \lambda $ that are commonly targeted for focal array or direct radiating elements at GEO applications. The power divider is fully metallic, a fact that makes it an ideal candidate for satellite applications. The design band is Ku-Tx (10.7–12.75 GHz), presenting a Return Loss better than 20 dB and an input-output isolation of the orthogonal modes better than 30 dB. The exciter is also subjected to sensitivity analysis for estimating its manufacturing tolerances, exhibiting a robust behavior to dimensional variations, while its losses are also evaluated around 0.1 dB when aluminum parts are assumed. Finally, a compact topology of a $2.5 \lambda $ aperture size array in a $2 \times 2$ scheme was designed and optimized where the level of aperture efficiency was the principal design goal. The array is after connected to the exciter to obtain the final feed system.

I. Introduction

With the advancement of satellite communications, more compact and efficient integrated microwave components are emerging. Spectral efficiency can be achieved by the use of dual polarization, which enables the augmentation of the data transmission capacity within a defined bandwidth. An orthomode transducer (OMT) is a microwave component, which separates or combines orthogonal polarizations and is commonly used to feed horn antennas in dual-polarization [1] .