TEM-mode power dividers and phase shifters - Antenna matching unit for the GEOS satellite

A number of matched power dividers and fixed (differential) phase shifters are described. It is shown how each power divider can be combined with a phase shifter to form a power divider of equal division and 180 deg phase difference between the two output signals. An experimental power divider unit consisting of two equal, matched 3 dB power dividers is presented. The phase difference of signals at the output of each divider is 180 deg. The unit will be part of the VHF antenna feed in the geostationary satellite GEOS. Each divider in the experimental unit consists of two quarterwavelength sections of offset broadside coupled striplines and an external coaxial cable for phase compensation. To minimize size and weight the coupled sections are folded in a meander structure. As size is reduced the coupling in the meander structure becomes tighter. The tight coupling causes a degradation of performance depending on different electrical lengths of the even and the odd mode in each of the two coupled sections. Methods to equalize these lengths are presented.