In this paper, a structure of a patch antenna operating at 0.5 GHz is proposed for ground-penetrating radar (GPR) applications, with an optimized performance at low frequencies. The structure was designed using FR4 substrate, with a 4.4 permittivity value, and a tangent loss equivalent to 0.021. The prototype design is backed by an optimized rectangular reflector, which has improved the antenna gain and directivity. The performance of the antenna is evaluated in terms of the return loss, gain, and the radiation pattern for two cases, with and without a reflector. When using the reflector, a good radiation pattern is obtained, a wide operational bandwidth ranging from 0.4GHz and 1.25 GHz is achieved, and an increased gain from 4.3 to 7.43dB was realized.

In this paper, the design and simulation of a symmetrical waveguide filter are presented based on the insertion loss method. The designed WR-34 waveguide filter is operating at 28 GHz, where its dimensions are a=4.32mm and b=8.64mm, a fractional bandwidth of 2.15% a return loss level better than 16 dB, a frequency range from 22Ghz to 33 GHz. The structure is a 5th-order bandpass filter with five resonators and six symmetrical circular inductive irises. In order to optimize the frequency response, five tuning screws were added to the center of each resonator, while two other screws were positioned before the first iris and the last iris from the wave ports. The simulation model of the filter is developed in two different simulators ANSYS high-frequency Structure Simulator (HFSS) and CST Studio Suite so as to validate the obtained results and to depict the effects of tuning screws on the S-parameters of the filter while generating scenarios depending on the depth of penetration of each screw.