Communications device capable of coupling current reduction

A communications device comprising:

• a first casing;
• a second casing coupled movably to said first casing, said second casing being movable relative to said first casing between a covering position and an uncovering position;
• and
• an antenna disposed in one of said first and second casings;
• wherein said first casing includes a first metal layer part, said second casing includes a second metal layer part, and said antenna is adjacent to said first and second metal layer parts when said second casing is at the covering position;
• wherein said first metal layer part has a surface that confronts said second metal layer part when said second casing is at the covering position and that is formed with a plurality of first recesses;
• and
• wherein said second metal layer part has a surface that confronts said first metal layer part when said second casing is at the covering position and that is formed with a plurality of second recesses;
• wherein each of said first and second recesses has outer and inner sections respectively proximate to and distal from said surface of the corresponding one of said first and second metal layer parts, said outer section being wider than said inner section;
• geometric centers of adjacent ones of said first recesses are spaced apart by a distance not more than 0.25 λ of a frequency at which said antenna operates, in which λ is a wavelength of signals at the frequency, and geometric centers of adjacent ones of said second recesses are spaced apart by a distance not more than 0.25 λ of the frequency.