San Diego-based internal antenna developer Ethertronics raised an additional $4 million in a secondary round of venture funding, according to a regulatory filing yesterday. Details of the funding, which were first reported today by socaltech.com, were not disclosed in the filing, but a representative of Ridgewood Capital, a private equity firm with offices in Ridgewood, NJ, and Palo Alto, CA, has joined Ethertronics’ board. Prior venture investors include Excelsior Venture Partners of Stamford, CT, and the Silicon Valley office of Sevin Rosen Funds.