Channel Selectivity of Satellite Transponders with the Antenna Combined with a Size-Reduced Metallic Waveguide Bandpass Filter Having Thin Metamaterial Resonators  
[PERSON]  
1 Department of Information & Telecommunication Engineering, Incheon National University,  
Incheon 22012, Republic of Korea 2  
[PERSON]  
1 Department of Information & Telecommunication Engineering, Incheon National University,  
Incheon 22012, Republic of Korea 2  
[PERSON]  
2 The Public Safety AI Research Section, Electronics and Telecommunications Research Institute,  
Daejeon 34129, Republic of Korea 2  
[PERSON]  
2 The Public Safety AI Research Section, Electronics and Telecommunications Research Institute,  
Daejeon 34129, Republic of Korea 2  
[PERSON]  
1 Department of Information & Telecommunication Engineering, Incheon National University,  
Incheon 22012, Republic of Korea 2  
Footnote 1: email: {cho,j.soo,y.shin,w.sjohn,w. The transponder is a wireless communication system that receives RF signals and transmits them whether it is a geostationary orbit (GEO) or LEO satellite. Its configuration is represented by the system block diagram comprising plenty of circuits and components from the receiver to the transmitter. The chain of the signal flow meets the components of signal amplification, channel selection, channel splitting and combining, switching, demodulation and modulation and so forth. For successful tasking, system integration (SI) is important, but the functions of the individual components are more prioritized. Active components connected to control blocks have an increased degree of freedom in meeting the requirements even after SI. As for passive components such as input and output multiplexers (MUXes) for channel splitting and combining, and filters for channel selection, functions are not controllable after fabrication and assembly. Great care should be taken of their design and fabrication. While active components such as MMIC amplifiers do not weigh much, passive components of waveguide (WG) filters and WG MUXes tend to be heavy. Along with the feed horn and reflector antenna, WG passive elements are of great concern in terms of size control and weight control to build a satellite transponder. This becomes a critical matter to the cost required in the making and maintaining of LEO and micro satellites. In the satellite communication, high-frequency signals must be so strong that they can travel hundreds to thousands of kilometers when emanated from the antenna. The filters, like other passive components in the feed assembly of the antenna, are made out of metallic waveguides to ensure high Q-factors and endure high power and the heat [3; 4; 5; 6; 7]. This is why the structures are bulky and heavy. Size-reduction of them is a crucial factor to cost-saving in developing and launching satellites. [PERSON] and [PERSON] showed second- and third-order rectangular WG BPFs [3]. Typical sized cavities are combined in series through irises for channel selectivity. [PERSON] and [PERSON] took an action to reduce the size of the WG filter by integrating coaxial lines with rectangular cavities [4]. The length of their third-order filter is the same as that of the conventional third-order BPFs. [PERSON] and [PERSON] put stepped impedance resonator (SIR) parts with cavity resonators coupled through a mixture of E-plane and H-plane steps [5]. Their WG BPF is longer than four wavelengths. [PERSON] and [PERSON] meandered the straight topology of a BPF to reduce the area the filter occupies [6]. The intered E-plane bend-added waveguide sections couple half-wavelength cavities and the total length has almost no charge. [PERSON] and [PERSON] changed a straight geometry to a staircase by opening the two spots on the broad wall of each cavity for coupling [7]. The trace in the longitudinal axis is decreased, but the total length is similar to reference 5.