In this article, we propose a dual notched‐band antenna with 2 slits for ultra‐wideband (UWB) applications. The antenna consists of a circular ground plane and a patch radiator with having 2 slits and a folding arm. The patch with folding arm is used to achieve UWB band while a V‐shaped and a split ring‐shaped slit are used to eliminate the interference from WLAN and 5G band, respectively. The width and length of the slits are optimized to obtain the necessary band notch characteristics. The prototype of the antenna having a total size of 75 × 10 mm2 is fabricated. Simulated and measured results show that the antenna covers the entire UWB frequency ranging from 2.754 to 14.656 GHz (127%) for VSWR < 2 except at notched bands. Moreover, the antenna successfully notched the WLAN band (5.15‐5.825 GHz) and 5G band (3.4‐3.7 GHz) besides of providing a stable gain and radiation patterns.

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We propose a new 2-step phase-shifting digital holographic optical encryption technique and analyze tolerance error for this cipher system. 2-step phase-shifting digital holograms are acquired by moving the PZT mirror with phase step of 0 or π/2 in the reference beam path of the Mach-Zehnder type interferometer. Digital hologram with the encrypted information is Fourier transform hologram and is recorded on CCD camera with 256 gray-level quantized intensities. The decryption performance of binary bit data and image data is analyzed by considering error factors. One of the most important errors is quantization error in detecting the digital hologram intensity on CCD. The more the number of quantization error pixels and the variation of gray-level increase, the more the number of error bits increases for decryption. Computer experiments show the results to be carried out encryption and decryption with the proposed method and the graph to analyze the tolerance of the quantization error in the system.

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