This paper presents a passive 2-D beam steering solution comprising of a triple-mode circular waveguide horn antenna operating at Ka-band frequency of 30 GHz, a pair of identical dielectric lenses employing Risley prism and a parabolic phase correcting surface. The circular waveguide horn antenna generates TE 11 , TM 01 and TE 21 modes independently. The pair of identical dielectric lenses employing the Risley prism concept are axially rotated individually and/or simultaneously to steer the radiated beam. The parabolic phase correcting structure is used to further improve the performance of the steered patterns. Overall, this antenna structure steers TE 11 , TM 01 and TE 21 modes patterns which makes it an attracting solution for tracking and communication applications. The proposed antenna system has been prototyped and experimentally verified in a compact antenna test range (CATR) chamber. The measured conical scan angles for TE 11 mode is found to be around ±40 • with gain deviation less than 3 dB. The TM 01 and TE 21 modes are steered with a scan angle covering ±30 • .

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In this article, details of a dual band microstrip patch antenna (MPA) array feed for an offset reflector antenna is presented. The main objective of the proposed structure is to achieve low cross‐polarization at Φ = 90° plane in the reflector pattern. Low cross‐polar levels in the reflector pattern are achieved by illuminating the reflector with fields of the proposed dual band feed structure. A centered circular array as the dual band feed structure is proposed in which the central radiating element is a dual mode circular MPA operating at 6 GHz and the surrounding circular ring of eight circular MPA elements operating at 4 GHz in the dominant mode. The dual mode central antenna uses the concept of conjugate field matching for cross‐polarization reduction. TM21 mode is excited at an appropriate ratio with the TM11 mode to achieve the proper field matching at 6 GHz. The radius of the surrounding circular array is varied to obtain cross‐polarization better than −30 dB at both the resonant frequencies. The offset reflector gain is found to be better than 37 dB with a 2.5 m parabolic reflector and F/D = 0.8 at both the operating frequencies.

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