A method of operation of an energy transmitter adapted to transmit energy to a particular energy harvester using radiative coupling, comprising: • for each time period (TP i) of a plurality of time periods ({TP i} i=0,1,...,I-1) where I is a positive integer that is greater than or equal to 2: o for each time slot (TS i,j) of one or more time slots ({TS i,j} j=0,1,...,J-1) where J is a positive integer that is greater than or equal to 1 for the time period (TP i): ▪ transmitting, during the time slot (TS i,j) of the time period (TP i) on a frequency f mod(i,2), a radio frequency signal (S T (i,j)) that is modulated with a signature of the particular energy harvester, wherein mod(*) is the modulo-2 operator such that f mod(i,2) is a first frequency f 0 for even values of i including i=0 and is a second frequency f 1 for odd values of i; and o attempting, during the time period (TP i), to receive, from the particular energy harvester on a frequency f mod(i+1,2), a radio frequency signal (S R (i)) that is modulated with the signature of the particular energy harvester, wherein mod(*) is the modulo-2 operator such that f mod(i+1,2) is the second frequency f 1 for even values of i including i=0 and is the first frequency f 0 for odd values of i. • for each time period (TP i) of a plurality of time periods ({TP i} i=0,1,...,I-1) where I is a positive integer that is greater than or equal to 2: o for each time slot (TS i,j) of one or more time slots ({TS i,j} j=0,1,...,J-1) where J is a positive integer that is greater than or equal to 1 for the time period (TP i): ▪ transmitting, during the time slot (TS i,j) of the time period (TP i) on a frequency f mod(i,2), a radio frequency signal (S T (i,j)) that is modulated with a signature of the particular energy harvester, wherein mod(*) is the modulo-2 operator such that f mod(i,2) is a first frequency f 0 for even values of i including i=0 and is a second frequency f 1 for odd values of i; and o attempting, during the time period (TP i), to receive, from the particular energy harvester on a frequency f mod(i+1,2), a radio frequency signal (S R (i)) that is modulated with the signature of the particular energy harvester, wherein mod(*) is the modulo-2 operator such that f mod(i+1,2) is the second frequency f 1 for even values of i including i=0 and is the first frequency f 0 for odd values of i. o for each time slot (TS i,j) of one or more time slots ({TS i,j} j=0,1,...,J-1) where J is a positive integer that is greater than or equal to 1 for the time period (TP i): ▪ transmitting, during the time slot (TS i,j) of the time period (TP i) on a frequency f mod(i,2), a radio frequency signal (S T (i,j)) that is modulated with a signature of the particular energy harvester, wherein mod(*) is the modulo-2 operator such that f mod(i,2) is a first frequency f 0 for even values of i including i=0 and is a second frequency f 1 for odd values of i; and ▪ transmitting, during the time slot (TS i,j) of the time period (TP i) on a frequency f mod(i,2), a radio frequency signal (S T (i,j)) that is modulated with a signature of the particular energy harvester, wherein mod(*) is the modulo-2 operator such that f mod(i,2) is a first frequency f 0 for even values of i including i=0 and is a second frequency f 1 for odd values of i; and o attempting, during the time period (TP i), to receive, from the particular energy harvester on a frequency f mod(i+1,2), a radio frequency signal (S R (i)) that is modulated with the signature of the particular energy harvester, wherein mod(*) is the modulo-2 operator such that f mod(i+1,2) is the second frequency f 1 for even values of i including i=0 and is the first frequency f 0 for odd values of i.