The ITU Radiocommunication Assembly considering:a)that the use of space-station antennas with the best available radiation patterns will lead to the most efficient use of the radio-frequency spectrum and the geostationary orbit;b)that both single feed elliptical (or circular) and multiple feed shaped beam antennas are used on operational space stations;c)that although improvements are being made in the design of space-station antennas, further information is still required before a reference radiation pattern can be adopted for coordination purposes;d)that the adoption of a design objective radiation pattern for space-station antennas will encourage the fabrication and use of orbit-efficient antennas;e)that it is only necessary to speciQ space-station antenna radiation characteristics in directions of potential interference for coordination purposes;f)that for wide applicability the mathematical expressions should be as simple as possible consistent with effective predictions;g)that nevertheless, the expressions should account for the characteristics of practical antenna systems and be adaptable to emerging technologies;h)that measurement difficulties lead to inaccuracies in the modelling of spacecraft antennas at large off-axis angles;j)that the size constraints of launch vehicles lead to limitations in the D A values of spacecraft antennas, particularly at lower frequencies such as the 614 GHz band;k)that space-station antenna pattern parameters such as reference point, coverage area, equivalent peak gain, that may be used to define a space-station reference antenna pattern, are found in Annex 1;h)that two computer programs have been developed to generate coverage contours (see Annex 2).