Embodiments of the subject application include a diagnostic apparatus including one or more antennas disposed on a thorax of a living body to direct radio frequency (RF) electromagnetic waves through tissue and output signals responsively to the waves that have passed through the tissue. The apparatus may also include processing circuitry configured to process the signals over time so as to measure one or more RF path characteristics of the RF electromagnetic waves. The RF path length may be defined by a length of time required for the RF waves to pass through the thorax to an antenna and/or pass to tissue and reflect therefrom to an antenna, based on the path characteristic to assess a fluid content of the tissue.診断装置は、無線周波数（ＲＦ）電磁波を、異なるそれぞれの方向から、心臓（２２）に向けて身体内に方向づけ、心臓から散乱される波に応答して、ＲＦ信号を出力するように、生体の胸部（３４）上の異なるそれぞれの場所に配置されるように構成されている、複数のアンテナ（２４、２６、２８、３０、３２）を含む。処理回路（４２、４４）は、心臓の運動の多次元測定を提供するように、ＲＦ信号を経時的に処理するように構成されている。
