Multiband feed using coaxial configuration

Abstract

We present design, analysis and test results of a dual-aperture coaxial multiband feed horn that operates at S, Ku, K and Ka bands. The design objectives are to achieve aperture efficiencies of 85% for S and Ku bands and 60% for K and Ka bands and cross-polarization level of À20 dB within 30 degree off-boresight for all bands. These values are deduced primarily from the reflector geometry, À10 dB reflector edge taper and moderate cross-polarization requirements for the secondary patterns. In our design the Ku, K and Ka bands are launched through a multiflared circular horn while the S band is launched through a coaxial horn. A method of moment based software is developed to analyze the structure including mutual coupling between the apertures. It is found that the aperture impedance significantly affects the S-band performance. For the high frequency bands, the mutual coupling between the circular and coaxial apertures plays an important role. The simulated results including mutual coupling effects agree well with the measured data. The multiband feed design allows a compact, low weight, single offset reflector configuration as opposed to a Cassegrain antenna system that requires two separate feeds and a dichroic subreflector to accommodate such widely separated bands.

A Tri-Band Autotrack Concentric Feed S-X-Ka for Ground Stations Related to Earth Observation

“…This constraint is such that it is impossible to simultaneously match the TE 21 mode required for monopulse tracking using these same inverted irises. No solution is known or published achieving a simultaneously wideband matching of TE 11 and TE 21 modes [2], [3], [4].…”

A compact feed horn with wide‐distributed operating bands of Ku/Ka/W

“…To the best knowledge of us, there are mainly three common methods to realize multiband‐characteristics for a reflector antenna: using multiple off‐set horns or active electronically scanned arrays reflected by respective sub‐reflectors, adopting frequency selective surfaces (FSS) as its sub‐reflectors with two horns placed to both sides of it, and employing only a single multiband feed horn in a reflector antenna. Comparing with the former solutions, designing a multiband horn comes to a more suitable candidate in the demand for simplicity.…”

“…Comparing with the former solutions, designing a multiband horn comes to a more suitable candidate in the demand for simplicity. Up to now, there are mainly two types of multiband feed horns, that is, multimode horns, with one cavity and coaxial horns with multiple cavities. Usually, the operating bandwidth of horns with single cavity is limited to 2.7:1, and the use of dielectric rod will increase the ratio to 5:1 or more .…”

Wideband turnstile junction coaxial waveguide orthomode transducer

“…This function can be also helpful in radio astronomy receivers for measuring polarized radiation. Quite a few feed antennas for satellite communication adopted coaxial structures to realize multi‐band functions and certain channel isolation: the outer coaxial waveguide propagates lower‐frequency signals, and the interior circular waveguide is dimensioned to propagate electromagnetic waves of higher frequency bands . The determination of single or dual concentric radiation apertures is based on specific frequency separation and electrical performance requirements.…”