Improving radiation performance by using a mutual coupled antenna

Hi All,

I wanted to know that is it possible to have a better radiation performance by using an antenna which is coupled to the original source antenna. consider it like this.

practical scenario: suppose i have one antenna which is having an omnidirectional radiation pattern, now i am using this antenna on a wearable module(on chest), because of which the performance is degraded on the body direction(on the back side) while in case of away from the body the performance is good and i am able to see good range as well.
The main factors are reflection and absorption due to which the radiated power is decreased in the direction of body.

now one way to improve this is by increasing the distance between the antenna and body(based on the some of the papers available), but is it possible to use an other antenna without feeding it but by using coupling (meaning it will absorb the power radiated by the source antenna and radiate some part of it as well.)

is the above possible? because i know that it will impact the radiated power because it'll absorb some of the power.so not sure whether any of that has been tried before. if it's possible then what i can try with that. any configuration, separation between the antennas, or any specific radiation pattern antenna should be used?

How to couple, through body? What is your frequency?
Practically I think it is better to use two separate antennas on chest and on the back, it may be realized on belt.