Hybrid cards or combo cards are a term applied to cards that contain two or more embedded chip technologies in a card. They offer a unique solution for updating existing badging system.
Low Frequency + High FrequencyC: LF + HF cards are the most common dual-frequency cards and usually have an HF antenna laminated around the outside of the card with a thick coil LF antenna contained within. Legacy LF systems like HID prox are often replaced by higher security HF implementations that still require usage of the original LF chip while all sites convert to the newer HF standard. eg
Mifare + EM4200
Mifare + TK4100
High Frequency + Ultra High Frequency: HF + UHF cards are becoming increasingly popular in loyalty and payment schemes that also want to track attendance and location of a customer. These hybrid cards generally have the UHF chip placed separately above or to the side of the HF chip to ensure there is no interference.
Mifare + UHF
Desfire + UHF
Low Frequency + Ultra High Frequency: LF + UHF cards are used in specialized situations where simple access control is required alongside personnel tracking. Like HF + UHF hybrid cards, LF + UHF is generally accomplished with the LF antenna running above or beside the UHF antenna.
EM4200 + UHF
TK4100 + UHF