Board Restarts continiously with External Antenna

Hi Good day guys, I need your help. I have a board running a custom linux distro. It has a SIM800C as part of the circuitry. When ever I insert the external antenna and try booting the board, the board will continuously be restarting. If i remove the antenna, the board boots well. Please what could be the problem?

When board boots well, is it connecting to the network properly?

Yes. Without the antenna it will connect well but the signal will be weak

The Antenna might be faulty. Are you sure its the right antenna?
Or is it touching ground when connected to the module? Check nearby parts with exposed ground pins or shields.

I guess that could be the possible fault from what you are saying. The body of the antenna is grounded. Is that wrong? Sorry for my late reply

The body should be grounded. ITs probably one of the power pins or data which are shorting to ground adn restarting the bord