Recently, we have proposed a gravitational form of the electromagnetic Chu limit.  The Chu limit is a 50-year old fundamental limit in electromagnetics that serves a central role in the design of small antennas.

    In our 2018 Phys Rev D article below, a  simple formula is derived for the Q (quality factor) of gravitational radiation sources (gravitational antennas), similar to the Chu limit that sets bounds on the achievable Q governing the ratio of stored energy to radiated energy in the electromagnetic fields of antennas. Observed gravitational Q is plotted in the 2018 Phys Rev D article below, using recent measured gravitational-wave data for a gravitationally-small binary neutron star inspiral.

    The 2018 APS conference paper below shows the earliest preliminary results in our investigation of the gravitational form of the Chu limit.