A 3D-Printed Horn Antenna with Integrated Septum and Circular-Polarized Radiation

A horn antenna with an embedded septum is proposed in this paper, based on the 3D printing technique. The horn is in terms of circular waveguides (CWGs), with a transition connecting the commercial rectangular waveguide (RWG) to the CWG throat of the conical horn antenna. To produce circular polarization (CP) in radiation, a dielectric septum is utilized for phase variation, and it is designed based on the electric property of the resin material used in the masked stereolithography (MSLA) technique. By rotating the septum at a certain angle inside the horn antenna, the phase difference between two orthogonal modes can be customized for CP. Moreover, the proposed horn antenna with the integrated dielectric septum can be printed as a whole in fabrication. For demonstration, a horn antenna with an integrated septum is designed and simulated. Simulation verifies CP radiation with low reflection. Such an integrated CP horn antenna has the advantages of minimized dimensions, lightweight, low fabrication cost, and enhanced tolerance in fabrication.

I Introduction

In communication and detection systems, antennas are used as a transition from circuits to free space, and antennas with various properties have been proposed at millimeter and microwave frequencies. Low sidelobes in radiation patterns are desired to mitigate signal interference [1], [2], and the main beam can also be steered in tracking and sensing applications [3]-[5]. Apart from modification of radiation patterns, the type of polarization in radiation also plays an important role in practice. Compared with linear polarization (LP), circular polarization (CP) could resist multipath distortion and improve polarization matching in wireless communications [6]. Therefore, it is worthwhile to investigate methods of LP-to-CP transformation.