The financial news service cited an unnamed source who claimed that Ruben Caballero, a senior engineer, told the Apple CEO last year that the antenna design could result in dropped calls. The source said one of Apple's mobile operator partners also voiced concerns over call quality before the iPhone 4 was launched last month.
Apple has faced criticism from both mobile phone users and industry analysts over iPhone 4 signal problems. Soon after the handset was launched in June, users began complaining of weak signal strength and even dropped calls if the handset was held by its lower left side.
At the beginning on this month, Apple published an open letter saying there was a problem with how the signal bars are calculated by the handset.
Apple is to host a press conference today, which is expected to cover the antenna issues plaguing the company's iPhone 4.