Abstarct: Abstract In this thesis we designed a filtering antenna for fifth generation communication applications in which the filter part is developed as a two-band multi-mode filter. We use the new and upgraded version of coupled transmition line model to this end. In the upper part of the transmission line, there are 2 pairs of U-shaped resonators, one side of each U-shaped resonator is coupled with the transmission line, the other side is coupled with the second U-shaped resonator, and the third side of the U-shaped resonator is free of coupling with any structure. We need a pair of U-shaped resonators to create each pass band, while only one U-shaped resonator is used to create each stop band, but when we use 2 identical U-shaped resonators to create a stop band, the attenuation value increases. They will be added together and as a result, the desired stop band will be removed with 2 times intensity. As a result, the proposed multi-mode filter consists of a slotted transmission line (there is a gap between the transmission lines) and 4 U-shaped resonators, 5 pins and 4 varactor diodes. The amount of loss and ripple of the proposed multi-mode filter in the 2-band and single-band pass filter mode is less than 0.5 db to cover 5G bands with 3.4-3.7 GHz and 5.1-5.3 GHz frequency bands. In the proposed filter, a total of 4 resonators are used, and these 4 resonators play the role of the pass band in the 2 band pass filter mode and exactly the same resonator play the role of the stop band in the stop band mode. For this reason, the final dimensions of the proposed multi-mode filter with 7 different modes are 33.4 mm * 18.6 mm * 0.508 mm. Also, if this filter is integrated with the UWB antenna, its operating modes and frequency bands will not change so much, which is also favorable for our purpose.