GPS has been widely used in intercom stations and wireless car intercom devices to provide positioning for users who use radio devices. When GPS is used on handheld walkie-talkies, we generally don't see the antenna, and there is a GPS chip preset on the PCB. However, the GPS antenna interface that is generally reserved on the radio vehicle station needs to be connected to a GPS antenna.
GPS antennas are divided into active antennas and passive antennas.
Passive antennas are mainly ceramic medium, and most of them are square designs. Since they don't need power supply, they are called passive antennas.
The active antenna is the antenna module to be powered. It is composed of ceramic antenna, LAN (low noise signal module), cables, connectors, plus a sealed waterproof ring, which has high gain and strong anti-interference.
Active antenna passive antenna
• Compared with passive antennas, it can tolerate smaller impedance mismatches or cable lengths
• Help keep the receiver noise figure low
• Compared with passive antennas (if equipped with filters), it is less affected by antenna cable interference
• It will not increase any power budget.
• The ceramic chip is directly connected to the RF-IN pin of the module, the connection method is simple in structure, and the standard ceramic chip is low in cost, mature in technology, and small in space. It is suitable for equipment that emphasizes compact space.
• Compared with passive antennas, it requires more power (approximately 10 to 60 mW)
• The layout of the antenna is from the antenna pin directly to the RF-IN pin of the module. This wire needs to be matched with 50 ohm impedance.
• There should be no electromagnetic interference near the antenna.
• The use of passive GPS antennas has higher requirements for PCB design and the EMI design of the whole machine.
