Electronic technology supplier Stadium Group is buying a wireless electronics group for up to £8m.Stadium is acquiring United Wireless, which serves customers in the automotive, telematics, vending, industrial equipment and asset tracking sectors.During the first nine months of this financial year, United achieved unaudited sales of £6m and pre-tax earnings before interest of £900,000.For the rest of the year, Stadium expects United to make a small contribution to the group's profits and to significantly increase the enlarged group's earnings in 2015.The group said the deal would add wireless connections to its capabilities in power supplies, electronic manufacturing services, interfacesx and displays.Shares rose 7p or 10.6% to 73p at 12:15 in London.PW