A System of Hemispherical Antenna Arrays for Noninvasive Deep Brain Stimulation

A system of hemispherical antenna arrays consisting of 299 elements operating at a carrier frequency of 3.6 GHz has been designed and simulated. The array elements are distributed uniformly, on two concentric hemispheres, on top of the surface of a human’s brain, which is represented as a hemispherical surface with a radius of 9.5 cm. The outer array consists of 171 elements, and the inner array consists of 128 elements (i.e., total of 299 elements). The radial distances between the human brain and the inner array and the inner and outer arrays are 1.5 cm and 2.08 cm, respectively. The electromagnetic fields inside the brain are found by treating the array system as a boundary-valued problem. A beam-focusing technique focuses the total magnetic intensity to a desired point or multiple points in the brain. This beam-focusing technique aims to target a specific neuron within the brain and induce correct neuron firing to elevate the symptoms of Parkinson’s disease. Since neurons respond to low frequencies (≈10 Hz), two modulating schemes are used to modulate the carrier signal and allow it to have a low-frequency envelope. The first scheme allows each antenna element to transmit a superposition of sinusoidal signals with 51 different frequencies, varying as multiples of 10 Hz but centered around 3.6 GHz. The second scheme is achieved with each antenna element transmitting at a single but distinct frequency centered around 3.6 GHz. The variation of the frequency of operation from one element to the other is 10 Hz. The slight variations between the different frequencies of the antenna elements will be used to achieve a low-frequency envelope. This multi-frequency signaling enables the carrier signal to be modulated with any real-time periodic signal desired.