by one end of radiating loads the other end being r f coupled to the mast 10 these loads are matched to the characteristic impedance of the helices with respect to the mast 10 which is 200 ohms and thus only traveling waves can be excited on the helices in order to excite the helices the coaxial line 12 is coupled to the center of a t shaped coaxial section 26 the horizontally disposed portion of which has a characteristic impedance of 100 ohms and the vertical portion of which has a 50 ohm impedance t section 26 has an outer conductor 28 which is electrically connected to the mast 10 at positions 29 and an inner conductor 30 which is isolated from mast 10 but which is coupled to and directly applies power to the lower ends 20a and 24a of helices 20 and 24 respectively to provide the circularly polarized radiation pattern circumferentially adjacent helices must be 180 u00b0 out of phase at their lower ends this is achieved through the use of half wave long belt lines 32 and 34 these belt lines 32 and 34 have a characteristic impedance of 200 ohms to match that of the helices 22 and 18 respectively at.