Heart Beat Detection using UWB(CMOS) Radar chip is a pretty exciting challenge. An important part of the system will be the antenna which should operate in UWB Frequency Range and should be Directive Enough for Heartbeat Detection. Any suggestions or Ideas about Which antennas you think are suitable for this purpose and why ??? It is preferable that Antenna should be planar, physically and electrically compact aswell. Any Ideas and suggections are welcome.
You can make a slotted antenna. It has high gain,its planar, good directivity.
Making an slotted array antenna will increase your gain.
here is another type of antenna which correspond to your requirements.
Intuitively, I think that an UWB antenna must be a kind of travelling wave design, e.g. a logper structure. I guess, you mean with "planar" a directional characteristic perpendicular to the antenna plane, this probably can't work for UWB.
But I'm neither an expert for UWB nor planar antennas.
Have done a little work in this area. Your problem will be the massive reflection from the air gap between the antenna and the er=~40 flesh. I would recommend a stripline type antenna, with a burried vivaldi pattern, in some sort of very high dielectric-constant ceramic, pressed right against the skin.
In principle no signal with a frequency higher than ~1 GHz would penetrate deep enough in human tissue to sense directly the heart movement.
There were methods of microwave or light reflection from chest skin that can detect heartbeat non-contact. The simplest method is the finger or ear sensor using light or IR which is quite common.
UWB may be capable to sense minor motions of a body buried in rubble or behind a wall, so even human heartbeat can be sensed.
Locating directly a microwave antenna changes it in the "applicator". The problem of air-tissue boundary and introducing an unknown and variable mismatch has been solved by using deionized water or alumina powder to reduce the mismatch.