An air-inlet duct for a gas turbine engine, the air-inlet duct comprising a particle separator formed to include an inlet passageway for receiving a stream of air, a compressor passageway that extends downstream from the inlet passageway, and a scavenge passageway that extends downstream from the inlet passageway and that is positioned radially outward of the compressor passageway, the particle separator configured to receive atmospheric air laden with fine particles and large particles and to direct the large particles into the scavenge passageway while allowing the atmospheric air to move into the compressor passageway thereby reducing the number of large particles that enter the compressor passageway; and an agglomerator configured to emit an electro-magnetic field into the inlet passageway to charge the fine particles in the inlet passageway to cause the fine particles to be attracted to one another and cluster together to form large particles directed into the scavenge passageway by the particle separator to reduce the number of fine particles directed into the compressor passageway; the air-inlet duct being characterised in that the particle separator includes an outer wall spaced apart from an engine rotation axis, an inner wall located between the outer wall and the engine rotation axis, the inner wall and the outer wall defining the inlet passageway therebetween, and a splitter located between the outer wall and the inner wall and including an outer splitter surface that cooperates with the outer wall to define the scavenge passageway therebetween and an inner splitter surface cooperating with the inner wall to define the compressor passageway therebetween; and (a) the inner wall, the outer wall, and the splitter include electromagnetically conductive material and the agglomerator includes an electrical charge source configured to electrically charge at least one of the inner wall, the outer wall, and the splitter to emit the electro-magnetic field into the inlet passageway; or (b) the agglomerator includes i) a spiral-shaped conductive element coupled to the outer splitter surface and arranged around the engine rotation axis and ii) an electrical charge source configured to electrically charge the spiral-shaped conductive element; or (c) the outer splitter surface is coupled to the inner splitter surface at a splitter tip of the splitter, the splitter tip includes an electro-magnetically transparent window, the agglomerator includes an antenna located in the splitter tip, and the antenna is configured to emit the electro-magnetic field through the electro-magnetically transparent window. (a) the inner wall, the outer wall, and the splitter include electromagnetically conductive material and the agglomerator includes an electrical charge source configured to electrically charge at least one of the inner wall, the outer wall, and the splitter to emit the electro-magnetic field into the inlet passageway; or (b) the agglomerator includes i) a spiral-shaped conductive element coupled to the outer splitter surface and arranged around the engine rotation axis and ii) an electrical charge source configured to electrically charge the spiral-shaped conductive element; or (c) the outer splitter surface is coupled to the inner splitter surface at a splitter tip of the splitter, the splitter tip includes an electro-magnetically transparent window, the agglomerator includes an antenna located in the splitter tip, and the antenna is configured to emit the electro-magnetic field through the electro-magnetically transparent window.