Embodiments are provided for determining and managing an inventory. The position of an object in an inventory may be determined by utilizing an interrogator to send multiple request signals to a tag attached to the object. Each of the request signals may be communicated by the interrogator at a different frequency. The interrogator may then receive multiple reply signals from the tag. The interrogator may then determine the position of the tag (and thus the object) along a transmission line from phase measurements of the reply signals. A dispenser inventory may be managed. The dispenser may identify an ingredient packaging to be inserted into an ingredient matrix of the dispenser. The dispenser may then receive a user input of a location within the ingredient matrix where the identified ingredient packaging has been inserted.