Fig. 8: Measured signal structures for validating the secure-zone characteristics and broadband performance of the proposed DIM scheme where the red circular marker represents the reference constellation symbols. | Nature Communications

Fig. 8: Measured signal structures for validating the secure-zone characteristics and broadband performance of the proposed DIM scheme where the red circular marker represents the reference constellation symbols.

From: Two-dimensional and high-order directional information modulations for secure communications based on programmable metasurface

Fig. 8: Measured signal structures for validating the secure-zone characteristics and broadband performance of the proposed DIM scheme where the red circular marker represents the reference constellation symbols.The alternative text for this image may have been generated using AI.

a–d Measured symbols that validate the feature of a secure zone. a The measured symbols of the single-channel 8PSK in the directions \((\theta,\, \varphi )=(-24.5^{\circ }\sim -13.5^{\circ },\, 0^{\circ }\, )\). b The measured symbols of the single-channel 64QAM in the directions \((\theta,\, \varphi )=(19^{\circ }\sim 24.5^{\circ },\, 0^{\circ }\, )\). c The measured symbols of 16QAM in the directions of \((\theta,\, \varphi )=(23.5^{\circ } \sim 34^{\circ },\, 0^{\circ }\, )\). d The measured symbols of 16QAM in the directions of \((\theta,\, \varphi )=(23.5^{\circ }\sim 34^{\circ },\, 90^{\circ }\, )\). e–h Measured symbols that validate the broadband performance of the proposed DIM scheme. e The measured symbols of 8PSK with the frequency range 10.3 ~ 11.8 GHz. f The measured symbols of 64QAM with the frequency range 10.7 ~ 11.6 GHz. g The measured symbols of 16QAM in the direction \((\theta,\, \varphi )=(28.5^{\circ },\, 0^{\circ }\, )\) with the frequency range 10.6 ~ 11.4 GHz. h The measured symbols of 16QAM in the direction \((\theta,\, \varphi )=(28.5^{\circ },\, 90^{\circ }\, )\) with the frequency range 10.6 ~ 11.4 GHz.

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