A high-attenuation waveguide filter using electromagnetic bandgap (EBG) substrates is introduced. With a simple design modification on the EBG covers, the waveguide filter produced an almost full Ku-band rejection bandwidth showing better than 20 dB input-to-output isolation from 12.3 to 17.2 GHz.

A microstrip phase shifter design that uses a reconfigurable metal pattern on the EBG ground plate is introduced. The EBG ground plate metal pattern contains a linear array of thin slots with switching devices loaded at the center. This design can vary the phase constant with minimum mismatch loss over a large frequency bandwidth. Several test ground plates without actual switching devices were used to verify the design concept.

In Feb 2021, As the competition for commercialization of 5G mobile communication has been increasing, 5G SA Network and Vo5G are expected to be commercialized soon. 5G mobile communication aims to provide 20 Gbps transmission speed which is 20 times faster than 4G mobile communication, connection of at least 1 million devices per 1 km2, and 1 ms transmission delay which is 10 times shorter than 4G. To meet this, various technological developments were required, and various technologies such as Massive MIMO (Multiple-Input and Multiple-Output), mmWave, and small cell network were developed and applied in the area of 5G access network. However, in the core network area, the components constituting the LTE (Long Term Evolution) core network are utilized as they are in the NSA (Non-Standalone) architecture, and only the changes in the SA (Standalone) architecture have occurred. Also, in the network area for providing the voice service, the IMS (IP Multimedia Subsystem) infrastructure is still used in the SA architecture. Here, the issue is that while 5G mobile communication is evolving openly to provide various services, security elements are vulnerable to various cyber-attacks because they maintain the same form as before. Therefore, in this paper, we will look at what the network standard for 5G voice service provision consists of, and what are the vulnerable problems in terms of security. And We Suggest Possible Attack Scenario using Security Issue, We also want to consider whether these problems can actually occur and what is the countermeasure.

A new microstrip compatible phase shifter circuit is introduced. The phase shifter uses a strip-type electromagnetic bandgap (EBG) substrate in place of the solid metal ground plane. Such EBG substrates, when made of ferroelectric materials, can produce variable phase constants useful for phase shifter applications. Test models using two different EBG substrates with dielectric constants of 9.2 and 10.2 showed 44.5 degrees of phase difference with 1.7 dB of added insertion loss at 10 GHz from a line originally 504 degrees long.