{'fraction_non_alphanumeric': 0.010752688172043012, 'fraction_numerical': 0.0, 'mean_word_length': 5.016129032258065, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Bandpass Grids With Annular Apertures

A rigorous theory describing the diffraction of a plane wave by a doubly-periodic array of annular apertures in a thick, perfectly conducting screen is developed. It is found that such a structure exhibits excellent bandpass characteristics which can be adjusted by changing the size of the apertures and the thickness of the screen.