One of Asia’s largest provider of rail transportation control systems had placed an order of ST221 series VHF transportation antennas from Sinclair at the end of 2018 for an overseas project. When Sinclair received the frequencies from the customer, it was quickly realized that something didn’t seem right. Based on the quantity ordered, Sinclair was able to deduce that the customer had planned to use only one antenna on each train. The frequency plan showed a 1.9MHz TX span and a 1.9MHz RX span with a 4.6MHz TX/RX separation. Essentially, the customer wanted to have one antenna to cover the entire RF system frequency range that is 6.5MHz wide.