I know there are some obstacles to overcome, but I'm wondering how good the idea would be in theory. First though, a few sub-questions before the main one: 1: The radiation in a microwave food cooker is like a laser (hence the 'hotspots' in food). Is it possible for microwaves to more diffusely spread their radiation through say, an array of mini-emitters, or by the use of a lens or even by simply using multiple reflections before the laser hits the food? This would then prevent hotspots and a spinny plate thing. If so, then why don't microwave ovens use this technique? 2: Is it also possible to make the aforementioned microwave laser silent, or is there something inherent to the technology that forces it to sound like a jet engine? Main question now: Ignoring the loss of radiation (which metal walls can solve using reflection), how sensible is it to use *perfectly diffuse* microwave radiation as a replacement to space heaters for use in the living room? Wikipedia speaks of the relatively limited health effects of general microwave radiation (more 'heating/burn' territory being non-ionizing, but there have been reports of 'clicking/buzzing in the ear' and even cataracts (stronger/focused radiation in that case?) ); however "microwave" covers a broad range of frequencies from 300 Mhz to 300 Ghz, and not just the frequency used for microwave cooking (2.45 Ghz, or down to 915 Mhz used for large industrial microwaves). If there were any concerns, one could increase the Ghz to something approaching infrared to reduce penetration maybe. I just think it would be neat to have a 'holistic' warming rather than the relatively surface-style warming of near infrared/convection that ordinary heaters provide. Apparently, suanas use far infrared radiation (3000-15000 GHz) which presumably penetrates further into the body than near infrared radiation (15000-430,000 GHz), though I'm not sure if it penetrates through the body completely.