Dual-band antenna using high/low efficiency feed horn for optimal radiation patterns

A dual-band antenna system configured to transmit and/or receive microwave beams over two or more frequency bands with substantially similar beam widths and substantially similar sidelobe levels is disclosed. The antenna system includes at least one reflector and at least one feed horn, the horn configured to provide a first efficiency over a first frequency band and lower efficiencies over one or more second frequency bands. The horn includes a substantially conical wall having an internal surface with a variable slope. The internal surface includes one or more slope discontinuities, wherein the slope discontinuities are configured to generate primarily TE1,m modes within the first frequency band and within the second frequency bands and generate TM1,n modes substantially only within the second frequency bands.