The present disclosure is directed to a system and method for amplifying Radio Frequency (RF) signals. In some implementations, a system includes a first interface, a second interface, secure memory, a user-interface module, a processing module, and an amplification module. The first interface connects to a microSD slot of a mobile host device. The second interface includes an internal antenna for wirelessly communicating with retail terminals. The secure memory stores user credentials and a payment application used to execute financial transactions with the retail terminals. The processing module executes the payment application using the user credentials in response to at least a transaction request received by the RF module and transmits at least one transaction response to the retail terminal based, at least in part, on the executed payment application. The amplification module connected to a lead of the antenna and is configured to amplify at least received RF signals.