Shrinking cavities
1 min read
Recent research at the US National Institute of Standards and Technology has concluded that thin films made of ‘metamaterials’ – manmade composites engineered to offer unusual combinations of electromagnetic properties – can reduce the size of resonating circuits that generate microwaves. NIST says the work is a step forward in the quest to further shrink electronic devices.
The research team deduced the effects of placing a metafilm across the inside centre of a common type of resonator; a cavity in which microwaves continuously ricochet back and forth. To resonate, the cavity’s main dimension must be at least half the wavelength of the desired frequency so, for a mobile phone operating at 1GHz, the resonator would need to be about 15cm long. Whilst other researchers have shown that filling part of the cavity with bulk metamaterials allows resonators to be shrunk beyond the usual size limit, the NIST team showed the same effect can be achieved with a single metafilm, holding the possibility of smaller resonators, as well as less energy loss.
The metafilm creates an illusion that the resonator is longer than it is by shifting the phase of the electromagnetic energy as it passes through the metafilm.
