at the interface thus in this optimal case the reverse power 512 may have close to zero amplitude as shown by signal 504 and the ratio of reverse power 512 to forward power 510 is zero in this circumstance no error condition exists and the controller 214 sets a system message that operation is optimal in practice the impedance match of the tx antenna 204 to the body may not be optimal and some energy of the rf pulse 502 is reflected from the interface of the tx antenna 110 and the body this can occur for example if the tx antenna 110 is held somewhat away from the skin by a piece of clothing this non optimal antenna coupling causes a small portion of the forward rf energy to be reflected at the interface and this is depicted as signal 506 in this case the ratio of reverse power 512 to forward power 510 is small but a small ratio implies that most of the rf energy is still radiated from the tx antenna 110 so this condition is acceptable within the control algorithm this determination of acceptable reflection ratio may be made within controller subsystem 214 based upon a programmed threshold and the controller subsystem 214 may generate a low priority alert to be sent to the user interface in addition the controller subsystem 214 sensing the condition of a small reflection ratio may moderately increase the amplitude of the rf pulse 502 to compensate for the moderate loss of forward energy transfer to the implanted wireless neural stimulator 114 during daily operational use the tx antenna 110 might be accidentally removed from the body entirely in which case the tx antenna will have very poor coupling to the body if any.