We propose a design concept for flexible human head coil arrays applicable to a wide frequency range. Electrically, the design relies on high decoupling obtained through a controlled high mismatched connection to the low-impedance preamplifiers. Mechanically, the array is built into a neoprene EEG cap, and made of regular-copper flexible wire. The array layout is designed to have an axis to stretch along, therefore allowing tight fit to a variety of human-head sizes. A 32-channel prototype for 13C at 3T (32.1 MHz) is presented and evaluated, showing SNR performance superior to a 13C-dedicated volume coil.