To insert a spurious wave inhibiting filter into the removable antenna section for possible replacement to a built-in spurious waves, inhibiting the filter from an existing ship radar device, without having to undertake significant engineering works.

By inserting of a spurious wave inhibiting filter into the pedestal bond part in an antenna section, a power supply waveguide to the antenna end, a corner waveguide, and the circumference of a slot antenna high-frequency electric-wave input port replacement of a ship radar device, with the operation becoming inexpensive and less eliminated and, where a space being prepared in the pedestal section of inserting the spurious wave inhibiting filter is realized.