Abstract: A polarimetric antenna (20) comprises a length of circular waveguide (30) having a sidewall (32) with a cylindrical internal surface (34). The sidewall (32) has two longitudinal slots (38) that extend parallel to a longitudinal axis (36) of the waveguide (30) and are symmetrically positioned with respect to the circumference of the circular waveguide (30). A first rectangular waveguide (40) communicates with one of the longitudinal slots (38), and a second rectangular waveguide (42) communicates with the other longitudinal slot (38), but is short circuited by a closure (44) at one end thereof. A transverse closure (46) is positioned over the circular waveguide (30) at one end, the closure (46) having a first and a second transverse slot (48, 50) therein. These slots (48, 50), which are preferably arcuate in form, are positioned symmetrically with respect to a longitudinal axis (36) of the circular waveguide (30).

Abstract: An improved feed waveguide 15 for an antenna 10 is disclosed which reduces coupling junction phase errors. The improved feed waveguide 15 of the present invention includes first and second slotted parallel walls 35a and 37a along the length thereof. The first wall 35a includes a first elongate slot 27 therethrough having a first longitudinal axis 42. The second wall 37a includes a second elongate slot 32 which is located on the second wall 37a opposite the first slot 27 on the first wall 35a. The second slot 32 has a longitudinal axis 44 which is orthogonal to the longitudinal axis 42 of the first slot 27.

Abstract: A waveguide slotted array is disclosed, employing compound slots in a waveguide broad wall. The phase of the voltage excited in the slot is controlled by the slot offset and angle of inclination relative to the axis. Utilization of the additional phase control provided by the compound slots allows the beam of a traveling wave slot array to be placed far from broadside, without the need to operate the array at frequencies so close to the waveguide cutoff frequency that there is unacceptable frequency sensitivity. The beam may be placed at any angle independently of which end of the array contains the input and which end the load.

Abstract: Two contiguous half-height waveguides (12, 14) having a common broad wall (16) are provided with a pair of closely spaced equal length slots (20) and a single unbalanced-fed half-wave dipole (24) located parallel to and between the slots, with feed line coupled to the waveguide walls between the slots and provides for both longitudinal and transverse polarization. When the waveguides are excited in phase (even mode), the slots radiate similar to a single shunt slot with a longitudinal polarization. When the waveguides ae excited out of phase (an odd mode), the dipole is the primary radiator, radiating energy in a transverse polarization.

Abstract: A termination (20, 32) is placed in the opposing wall behind the center radiator (18c, 28c) of a multiple slot antenna array. The termination is inoperative when the array is excited for sum mode radiation patterns and is operative when the array is excited with difference mode radiation patterns. When the terminatrion is inoperative, the center slot radiator is excited along with the remaining slot radiators (18, 28) to produce the sum pattern. When the termination is operative, the center slot radiator is prevented from receiving excitation and a resultant difference pattern is produced by the remaining slot radiators (18, 28). Both E-plane and H-plane patterns can be achieved by the appropriate use of series slots and shunt slots. By eliminating the center slot (18c, 28c) in the difference pattern a reduction in side lobes results. This is an improvment over current practice where there are an even number of slots and no change of amplitude distribution--only a change of 180.degree.