I have seen pseudo news reports of this idea way back in the 1940's so evidently the concept has been around for a while. The idea then was to detonate explosives of the enemy in a war. Perhaps focused high energy beams of electromagnetic rays could manage this today but considering all the technology of robots around today in use to defuse explosives, this might indicate that there has yet to be success in applying the idea.

It might work if the radio waves can induce an electrical current in the explosives which may cause them to heat up but if these compounds are poor electrical conductors no current will be induced so maybe no heating.

You might have to use microwave devices which work the same way as the ovens to heat the explosives up. I may be wrong but I though these need water to be present in the material to aid the cooking effect. Could radio/microwaves cause the detonator to heat up and set it off? or alternatively fry the circuitry and disable the bomb?

People could get around a device like this by placing their explosives in a faraday cage to shield it from radio energy which would neccessitate sending a robot in to disable it.A device placed inside a metal car fuel tank would also be difficult to 'illuminate' with radio energy.

Contemporary plasticised high explosives require explosive shock to detonate. Heat, fire, even being shot will not detonate them. Only the shock of a blasting cap will cause the plastic explosives to explode. Microwaves would not have this effect.

I don't think RF waves are going to work. However, the US military is already field testing high-energy lasers to detonate landmines.

Seems to me that everything they learned about I.E.D's they learned from us. How is the bomb triggered? Remote or proximity? If by remote then your idea will work but use remote frequencies. If by phone have a remote dialing system that works at certain times of the day. Who know you might catch them in the act. Once bitten twice shy.