This feature is not on a current W3C standards track, but it is supported on the Firefox OS platform. Although implementations may change in the future and it is not supported widely across browsers, it is suitable for use in code dedicated to Firefox OS apps.
frequencyLowerBound property value indicates the minimum frequency down to which the
seek method searches for radio stations.
var max = instanceOfFMRadio.frequencyLowerBound
Return a number representing a frequence expressed in MHz (MegaHertz).
Not part of any specification.