Communicating radio astronomy implies talking about how radio telescopes work and how we produce images (or any kind of representation) out of radio data. 
We show two activities designed with the aim of presenting this fascinating way of studying the Universe to the widest possible public.
The first is a multisensorial map of the invisible Universe obtained from radio and spectroscopic data, contemporary addressing three senses: view, touch and hear. The exhibit, called "Sense the Universe", has been selected as part of the "Inspiring Stars" IAU exhibition. 
The second is an educational lab that make use of the pegs and pegboards (very familiar toys for children) to experiment and look into the concept of digital image resolution. The image to be reproduced with the pegs is placed under the pegboard, which is used as a colour sampler. When the nails are too big, fine sampling is not possible therefore we get low-res representations. Try yourself!