We investigate possible configurations for dual-band waveguide diplexing assemblies appropriate for use as feed systems for dual-reflector antennas. Specific applications are where the bands are well separated and, individually, have relatively wide bandwidths. Two crucial problems are addressed: the demanding bandwidth requirements of the feed horn and the subsequent means of diplexing the signals. We present results arising from the analysis of candidate systems and discuss a preferred option in detail.

Diplexing feed assemblies for application to dual-reflector antennas

A multifrequency, broadband, dual-polarized corrugated conical horn antenna is simultaneously fed a multiplicity of signals, two for each of five frequencies, with each of a pair of signals fed in each of two orthogonal planes for excitation of a desired spherical hybrid mode (HE 11 ) The lowest frequency is fed into the horn through orthogonal pairs of colinear slots, each pair being fed by coaxial tee power dividers Other signals are fed through a circular waveguide connected to the vertex Band reject cavities block the next higher frequency from passing through the low frequency feed slots The highest frequency signals are fed through orthogonal ports near the far end of the circular waveguide The intermediate frequency signals are fed through orthogonal ports spaced along the waveguide Filtering is incorporated for each to maintain isolation and low insertion loss, a quarterwave step transformer is used between the highest frequency (37 GHz) ports and the two next lower frequencies (21 GHz and 18 GHz) to provide a short circuit for these two lower frequencies, and a TM 11 mode generator for the highest frequency is used as a short circuit for the next lower frequency (1069 Ghz)

Multifrequency broadband polarized horn antenna

A multiple band antenna feed used with parabolic reflector antennas and the like. The feed is arranged as two coaxially disposed waveguides. A planar array of patch elements is disposed at the end of the coaxial waveguides so the energy in each band radiates from a common phase center. This simplifies the arrangement of associated subreflectors.

Multiple frequency antenna feed

Based on a systematic analysis the design and experimental studies on a composite dual-frequency feed with a single radiating aperture are presented. The criterion for selecting the ratio of the diameter of the corrugated guide excited at the lower frequency in the dominant mode to that of the dielectric rod, axially located within the guide and excited at the higher frequency in the dominant mode, is discussed. The constructional features of a typical dual-frequency feed designed for operation at S and X bands (with 2.68 GHz and 9.375 GHz as center frequencies, respectively) are outlined. The measured radiation patterns show good symmetry and sidelobe suppression over 20-percent bandwidth in S and X bands and are in good agreement with calculated patterns.

Propagation and radiation characteristics of dielectric loaded corrugated dual-frequency circular waveguide horn feeds

A coaxial turnstile junction ( 10 ) for combining and directing both satellite uplink and downlink signals. The junction ( 10 ) includes a tapered section ( 30 ) to provide better impedance matching of the downlink signal between a waveguide structure ( 14 ) and a plurality of symmetrically disposed downlink waveguides ( 38-44 ). The junction ( 10 ) includes a first end ( 26 ) that is in signal communication with an antenna feed horn ( 12 ). The junction ( 10 ) includes a cylindrical outer wall ( 28 ) and a cylindrical inner wall ( 18 ) that are coaxial and define an outer chamber ( 22 ) and an inner chamber ( 24 ). The outer wall ( 28 ) extends into the tapered section ( 30 ) where the tapered section ( 30 ) contacts the inner wall ( 18 ) and closes the outer chamber ( 22 ). The waveguides ( 38-44 ) are positioned around the outer wall ( 16 ) and are in signal communication with the outer chamber ( 22 ) through openings in the tapered section ( 30 ). Irises ( 46-52 ) are provided at the connection between the downlink waveguide ( 38-44 ) and the outer chamber ( 22 ) for impedance matching purposes. Satellite downlink signals from the downlink waveguides ( 38-44 ) are sent to the feed horn ( 12 ) through the outer chamber ( 22 ). Satellite uplink signals received by the feed horn ( 12 ) are directed through the inner chamber ( 24 ) to receiver circuitry. The dimensions of the irises ( 46-52 ) and the flare angle of the tapered section ( 30 ) are selected and optimized so that the downlink signal propagating down the waveguides ( 38-44 ) is impedance matched to the downlink signal propagating through the outer chamber ( 22 ).

Wideband TE11 mode coaxial turnstile junction

The design method of and experimental results obtained from a wide-band satellite antenna with a multifrequency primary horn is described. This antenna can be used in 4, 6, 20, and 30 GHz frequency bands. Some measured data of the primary horn and the antenna are reported. Consequently, the antenna efficiency is about 45-50 percent in all the above frequency bands.

Wide-band communication satellite antenna using a multifrequency primary horn

Most of the public infrastructure equipment currently in use was built during the period of high economic miracle and is rapidly aging. On the other hand, the number of workers who inspect those infrastructure facilities has been decreasing in recent years. In particular, the inspection work of underground buried infrastructure requires a great deal of labor and time, so the introduction of autonomous mobile robots is required from the viewpoint of improving the efficiency of inspection work and saving labor. High self-position estimation accuracy is required to identify the position by comparing the coordinates of autonomous movement and underground buried objects with the information of the ground penetrating radar. In this study, we constructed a two-dimensional relative positioning accuracy evaluation experimental system assuming inspection of underground buried objects by an autonomous mobile robot, and conducted self-position estimation experiments using an axle encoder and self-position estimation experiments using sensor fusion. 

Y. Kataoka

Papers

Wide-band communication satellite antenna using a multifrequency primary horn

Construction of 2D relative positioning accuracy evaluation experimental system for mobile robots for infrastructure inspection