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

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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