For an RAAF Wireless Op, the shoulder eagles would be in brown on tan, and the wireless ops sleeve badge either brown on tan cloth, or bronzed metal. The 'fist and sparks' (W/Ops) badge was worn on the right sleeve only as a rule.
As for rank, the RAAF had a type of chevron that was woven directly to the tan backing material, but these are hard to find. Tapes sewn on to tan material, white tape sewn on to tan material, Army style stripes and even white tapes sewn directly to the arm would all have been found in, say, the African theatre.
The small crown would generally be in bronzed metal, or brown thread on tan cloth, woven. Again, in places like the North African theatre, where supplies were not so plentiful, a brass crown would not be uncommon.