The proposed antenna in [7] offers broadside radiation pattern with small size and very simple feed network. Also, it has less optimization parameters and shows that the reflection coefficient of –10 dB over the frequencies 27–29.5 GHz. For simulation and optimization, CST an industry standard software is used which works on finite integration technique (FIT). Here, the four identical DD patch antennas form an array and are fed by one-to-four Wilkinson power dividers. In order to reduce the losses due to surface wave, the electromagnetic band gap (EBG) structure is introduced and simulated finally. The performance parameters such as side-lobe level (SLL), front-to-back ratio (FBR), gain, bandwidth, radiation efficiency and total efficiency of the metallic patch antenna, proposed DD patch antenna, and the proposed DD patch antenna with EBG structure are explained in [7], and it shows that the proposed DD patch array antenna is a good candidate for the future 5G mobile communication systems with the increased gain of 16.6 dBi and radiation efficiency of 71% which is low when compared with the conventional methods. Three different configurations of patch phase array antennas stated in [8] are fed with inset feed line and operating in 28 GHz. The antenna type 1 is designed such that the array feed line in the same direction and types 2 and 3 are designed with the antenna array feed line in the opposite direction. The measured and simulated results were discussed for the antenna excited at phase differences of 0Ɵ, 360Ɵ, and 180Ɵ. The results show that antenna 1 provides constructive interference while excited at 0Ɵ and 360Ɵ and achieves the gain of 8.64 dB and gives destructive interference while excited at 1800 and achieves the gain of 6.30 dB since the feed line is in the same direction. Antennas 2 and 3 provide destructive interference while excited at 0Ɵ and 360Ɵ and achieve the gain of 7.47 and 7.46 dB, respectively, and give constructive interference while excited at 180Ɵ and achieve the gain of 7.87 and 8.45 dB, respectively, since the feed line is in the opposite direction. Also, it offers good isolation performance over a wide frequency range from the patch size which is made small. A novel broadband-printed elliptical-slot antenna and a dual-band slot antenna are given in [9] which are able to cover the wide range of mm-wave frequency band 28–38 GHz. The broadband slot antenna is exited with 50-ohm proximity-coupled feed line, and it offers the impedance bandwidth of 20–40 GHz which covers the required frequency of 28 and 38 GHz for mm-wave applications. The dual-band slot antenna is designed by introducing a notch band of 30–35 GHz in the broadband antenna stated above. The proposed antennas provide the omnidirectional pattern and offer the gain of 5.3 and 5.6 dBi and radiation efficiency of 93 and 94%, respectively.