Medical thermal ablation apparatus for treatment of emphysema or COPD the apparatus comprising: a plurality of electromagnetic signal applicators, the plurality of electromagnetic signal applicators adapted to deliver electromagnetic energy to lung tissues for differential heating of diseased and healthier portions of the lung tissues, the plurality of electromagnetic signal applicators comprising a first set of two or more first electromagnetic signal applicators positionable on one side of a body to be treated and at a second set of at least one second electromagnetic signal applicators positionable on a second side of the body to be treated opposed to the first side such that the body is between the first and second electromagnetic signal applicators; a heating energy signal generator; characterised by further comprising: selector circuit connected to receive an output signal from the heating energy signal generator and to selectively apply the output signal between any of a plurality of pairs of the electromagnetic signal applicators, the pairs of the electromagnetic signal applicators each comprising one of the first electromagnetic signal applicators and one of the second electromagnetic signal applicators; a controller connected to control the selector circuit, the controller operable to switch from applying the output signal to a currently selected one of the pairs of electromagnetic signal applicators to applying the output signal to a different one of the pairs of electromagnetic signal applicators at spaced apart times. a plurality of electromagnetic signal applicators, the plurality of electromagnetic signal applicators adapted to deliver electromagnetic energy to lung tissues for differential heating of diseased and healthier portions of the lung tissues, the plurality of electromagnetic signal applicators comprising a first set of two or more first electromagnetic signal applicators positionable on one side of a body to be treated and at a second set of at least one second electromagnetic signal applicators positionable on a second side of the body to be treated opposed to the first side such that the body is between the first and second electromagnetic signal applicators; a heating energy signal generator; characterised by further comprising: selector circuit connected to receive an output signal from the heating energy signal generator and to selectively apply the output signal between any of a plurality of pairs of the electromagnetic signal applicators, the pairs of the electromagnetic signal applicators each comprising one of the first electromagnetic signal applicators and one of the second electromagnetic signal applicators; a controller connected to control the selector circuit, the controller operable to switch from applying the output signal to a currently selected one of the pairs of electromagnetic signal applicators to applying the output signal to a different one of the pairs of electromagnetic signal applicators at spaced apart times. selector circuit connected to receive an output signal from the heating energy signal generator and to selectively apply the output signal between any of a plurality of pairs of the electromagnetic signal applicators, the pairs of the electromagnetic signal applicators each comprising one of the first electromagnetic signal applicators and one of the second electromagnetic signal applicators; a controller connected to control the selector circuit, the controller operable to switch from applying the output signal to a currently selected one of the pairs of electromagnetic signal applicators to applying the output signal to a different one of the pairs of electromagnetic signal applicators at spaced apart times.