Radio systems products maker Filtronic saw a further weakening of demand from a large customer in the second half of its financial year, contributing to a slide into the red.Revenue from continuing operations in the year to 31 May 2010 slumped to £15.6m from £28.8m the year before. Loss before tax was £1.02m compared to a pre-tax profit in the previous year from continuing operations of £2.27m.Net cash at the end of the financial year was unchanged from a year earlier at £16.2m."The underlying market drivers for Point to Point backhaul market growth remain intact, although demand outlook through the summer remains constrained. Whilst overheads have been trimmed the group continues to invest in R&D [research & development] in order to position the company with competitive products to respond to market expectations of a 2011 demand recovery," the company's chairman, Howard Ford, said. The annual dividend has been maintained at 1.00p.