A longitudinal-shunt slot array with reflectors has been designed, built, and tested. The antenna is easily matched near the design frequency. The radiation pattern has an intensity within ±0.5 dB over a total angle of 15.6° in the H plane and 15.5° in the E plane. Gain is 19.7 dB which is 3.9 dB above that of a horn with a similar work area. By using energy-absorbing material, it is possible to produce a pattern in which the fields drop suddenly from the nearly constant values to nearly zero.