Hardware implementation of directional modulation system with a 2 element antenna array

Multiport Compact Stacked Patch Antenna With 360° Beam Steering for Generating Dynamic Directional Modulation

“…excited with feeding networks that enable the configuration of different radiation patterns. Several DM beamforming techniques have been reported in the open literature including: switches [3]- [6], a dual-beam method [7], reconfigurable attenuators and/or phase shifters [8]- [10], vector modulators [11]- [14] and the use of a Fourier Rotman lens [15].…”

“…When the number of array elements antennas in a DM system is less than four, the spacing between elements is typically larger than λ (free space wavelength) [7], [11] and tends to λ/2 as the number of elements in the array increases [5], [6], [8]- [10], [12]- [15]. In either case, the size of the resulting array is larger than several λ, which limits the use of DM to applications where the antenna size is not a constraint.…”

Spatial Data Focusing Using Time and IQ Resources for Wireless Geocasting

“…However, due to the limited set of states of the reconfigurable antennas, these schemes are restricted by limited flexibility and complex synthesis processes. The second type of DM transmitters, as presented in [6]- [9], act as an extension to beamforming, by calculating for each symbol a unique weighing vector for the array, such that symbols can only be unambiguously decoded in the beamforming main lobe direction. While being more synthesis friendly, these approaches, however, do not release the constraints of beamforming and serve mostly as a means of securing wireless links against eavesdropping in array sidelobe directions, providing only limited improvements in terms of spatial selectivity.…”