What role does the internal antenna in a contactless card play?

The internal antenna in a contactless card primarily serves the purpose of transmitting electrical energy to power the card's chip. When a contactless card is brought near a payment terminal, the terminal emits an electromagnetic field that interacts with the antenna in the card. This interaction generates a small amount of electrical energy, which powers the card’s chip and enables it to communicate with the terminal. This process is vital for the functioning of contactless payments, allowing for quick and efficient transactions without the need for physical contact with the terminal.

The other choices focus on aspects that do not pertain directly to the specific function of the antenna. For example, while cardholder information is crucial for transactions, it is not the antenna's role to convert this information into a digital format. Establishing a secure connection with the bank's database is a task primarily carried out by the card’s chip and the payment network, rather than the antenna itself. A backup function is generally outside the scope of an antenna's purpose; it is primarily designed for communication and energy transfer rather than for redundancy. Thus, the correct understanding of the antenna's function is essential for grasping how contactless payment technology operates at a fundamental level.