Opposition Leader Tony Abbott has struggled to explain the basics of his broadband policy, saying he is not a ''tech head''.

Mr Abbott was conspicuously absent when his colleagues, communications spokesman Tony Smith and finance spokesman Andrew Robb, yesterday unveiled the Coalition's $6 billion broadband plan.

It guarantees minimum broadband speeds of 12 megabits per second (mbps) for 97 per cent of homes, while Labor's national broadband network promises 100mbps to 99 per cent of households.

Mr Abbott was later questioned on how many towers the opposition would have to build to implement the plan, how many kilometres of fibre would be required to connect them, and what spectrum would be used to deliver the network.