Design of a Hemispherical Antenna Array Receiver for Medical Applications - Foundations on Natural and Artificial Computation - page 255

Design of a Hemispherical Antenna Array
Receiver for Medical Applications

Mohammad Safar and Robert W. Newcomb

Department of Electrical & Computer Engineering, University of Maryland,
College Park, MD, USA
[e-mail] , [e-mail]

Abstract. A hemispherical antenna array consisting of 42 elements was
proposed and simulated. The array is capable of receiving signals at 500
kHz. The array elements are distributed on a hemisphere to be placed
on a human's head. The function of the array is to receive brain waves
or signals from embedded electronics in the brain. By considering the
problem as a boundary valued problem with the source signal or field
being in the brain, the induced current on the antenna elements can
be determined using boundary conditions. A beamforming technique for
reception was used that made use of the orthogonality property of the
transverse electric fields to enable the array to receive from one or mul-
tiple points from within the brain.

Index Terms: Hemispherical array, Boundary valued problem (BVP),
Beaamforming.

1 Introduction

Antenna arrays have the ability to receive signals while improving the overall
signal-to-noise since they allow for constructive interference in the desired point
or direction of reception and destructive interference in all other directions. This
property can be put in use when considering medical applications where there
is a transmitter embedded inside the body and a receiver is needed to receive
signals from that transmitter [1]-[4].
The reception is achieved by using some kind of a beamforming algorithm.
This is usually done by first defining or calculating a real property of the signal
that will be maximum in the direction where the signal is coming from and
all what the designer have to do is try to scan for this maximum using some
kind of an optimization scheme. According to [5], the algorithms for direction
of arrival (DOA) estimation fall into the following 3 categories: (1) spectral-
based algorithm; (2) subspace-based methods & (3) parametric methods. In the
literature there are many kinds of reception strategies that fall in the above
categories [6]-[13].