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Modern K-/Ka-band satellite communications have become increasingly demanding in recent years with regard to the performance of the terminal antenna used in the link. These terminals should be high gain and broadband, as well as guarantee polarization diversity over a large field of view. A low profile is also highly desired to integrate the antenna system into a variety of moving platforms, such as aircraft and trains. An ultra-low-profile continuous transverse stub array is proposed here to tackle these challenges. The antenna array is realized in printed circuit board technology by adopting a contactless transition between the stacked-up layers without resorting to blind or buried vias. The proposed antenna is wideband (impedance matched within the 19–31 GHz band, i.e., ~50%) and provides multibeam radiation for polar angles as far as ±22.5°. The peak value of the gain is 19.7 dBi, and the maximum radiation efficiency equals 50%. Furthermore, the antenna array is combined with a dual-band polarization converter. The latter provides orthogonal circular polarization (CP) in two non-adjacent bands. The overall antenna system performs right- and left-hand CPs within the SatCom downlink and uplink in the K-/Ka-band, respectively. For each polarization, the axial ratio is below 3 dB over 9.47% and 4.42% fractional bandwidths, respectively. [ABSTRACT FROM AUTHOR]

We present here a novel architecture of high-gain continuous transverse stub (CTS) antenna array operating at E-band (71–86 GHz) with reduced sidelobe level (SLL). The antenna consists of an array of 16 long slots excited by a nonuniform parallel-plate waveguide (PPW) corporate feed network. The nonuniform excitation is achieved by the design of asymmetrical power dividers in PPW technology, for which simple analytical models are provided. Full-wave simulations are validated by measurements of a prototype fabricated in aluminum. The SLL is lower than −28 dB in the E-plane. Such an SLL is 15 dB lower than classical parallel-fed CTS arrays. The overall antenna SLL remains below −18 dB over the 75–86 GHz band. Its mean radiation efficiency is 60%, and the maximum efficiency of 85% is reached at 86 GHz. [ABSTRACT FROM AUTHOR]

A multibeam antenna system fed by a compact Rotman lens is presented in multilayer substrate integrated waveguide (SIW) technology. The lens is implemented in two layers using a new transition based on several star-shaped coupling slots and an SIW integrated reflector. Compared to standard rectangular coupling slots, this transition is broadband and maximizes power transfer between the two layers of the lens regardless the position of the beam port along the focal arc of the Rotman lens. The radiating part is an array of 15 slotted waveguides. These waveguides are centrally fed to enhance their bandwidth and reduce the “long line effect.” To validate the proposed concepts, an antenna system has been prototyped at 24.15 GHz. The designed transition leads to a physical size reduction of about 50% for the Rotman lens, and more than 33% for the antenna footprint compared to standard single-layer implementations. The experimental results demonstrate a scanning range of \pm 33^\circ and a 4% bandwidth for \textVSWR < 2; the isolation between input ports is better than - 10\;\textdB. [ABSTRACT FROM PUBLISHER]