In this thesis, the physical layer security analysis of millimeter wave (mmWave) ad hoc networks with multi-array antenna transmission is studied in the presence of different eavesdroppers' attacks. By exploiting the tools of stochastic geometry, the average achievable secrecy rate is derived in the presence of non-colluding and colluding passive eavesdroppers, taking into consideration the impact of blockages, directional beamforming, and Nakagami-m fading. Moreover, the mathematical expressions are derived in the presence of passive/active eavesdroppers for the secrecy performance metrics including connection outage probability, secrecy outage probability, and average achievable secrecy rate. The passive/active eavesdroppers operate in the full-duplex mode which can intercept the message signal and transmit a jamming signal simultaneously. Further, to establish secure transmission against the high eavesdroppers' capabilities, a simple yet two effective artificial noise (AN) transmission with either sectoring (Tx-AN technique) or null space linear precoder (Tx-AN/LP technique) is applied at the transmitting nodes. For both approaches, the total transmit power is divided into message transmit power and AN transmit power. In the Tx-AN technique, the main lobe beam of the AN array antenna of each transmitting node is not directed to its corresponding receiver and steered everywhere else to degrade the received data rate at the eavesdroppers. On the other hand, the Tx-AN/LP technique injects the AN into the null space of the legitimate receiver's channel with perfect knowledge of the channel state information between the typical transmitter and its receiver. Numerical and simulation results show that using the Tx-AN technique achieves up to three-fold improvement of the average secrecy rate over that without in the high power transmit regime (> 20 dBm). Besides, in the presence of passive/active eavesdroppers, the Tx-AN/LP technique is very effective in mitigating the effect of the jamming signals, achieving up to two-fold improvement in the average secrecy rate over that without. The results demonstrate the secrecy robustness of the Tx-AN and Tx-AN/LP techniques against increasing eavesdroppers' intensity. Finally, this thesis proves that the Tx-AN or Tx-AN/LP techniques are useful to improve the secrecy performance of the interference-limited mmWave ad hoc networks under various eavesdropping strategies.