# Analysis and Design of a Diplexing Power Divider for Ku-Band Satellite Applications
## 2 Geometry of the Proposed Diplexing Structure and Performance Analysis
### Analysis  
In the proposed design, signals between SIW channels are then divided or separated by shifting the vertical transition from the central axis to the narrow walls of the SIWs. Dividing or separating electromagnetic signals between SIW channels depends on the position of SMA connector 3. By relocating SMA connector 3 from the center of the SIW axis to its walls, the suggested topology modification has the potential to alter transition behavior significantly. Illustrated in Figure 2 are the scattering parameters of SMA connector 3, demonstrating an extended dielectric connector's role as via a coupling topology when situated along the central axis of the SIW. In this particular arrangement, the RF signal undergoes a division between SIW channels 1 and 2. Assigned as the input port, port 3 serves as the point of entry for the RF signal, which subsequently becomes distributed between the two aforementioned SIW channels (channels 1 and 2). This configuration  
Figure 1: Different views of the proposed diplexing network. (**a**) Full view schematic, (**b**) without copper layer (in place material) view, (**c**) side view, (**d**) view of the advanced SMA connector with extended dielectric, and (**e**) top view of each of the layers (all dimensions are in mm). showcases how the placement of SMA connector 3 along the SIW axis center can facilitate signal division and coupling through the extended dielectric connector. It is important to note that this arrangement holds implications for signal distribution and interaction within the SIW structure. Engineers and designers can leverage this insight to optimize signal routing, distribution, and interaction within the SIW, thereby tailoring the topology to specific performance objectives. The coupling values between the two output ports exhibited a notable similarity, while the reflection coefficient of port 3 was sufficiently low. By moving the transition toward the SIW walls, a distinct separation of electromagnetic signals emerges, channeling them into channels 1 and 2 at varying frequency bands. For optimization, the parameters Hs, Xoffset, Y1, and Y2 are changed. These four parameters have the most effect on scattering parameters. By working on these parameters, shifts occur in the values of inductance, capacitive reactance, and conductance within the impedance characteristics of the system. To determine the optimal values for these key parameters, comprehensive full-wave simulations employing CST software were executed. An evaluative exploration is undertaken through a parametrical analysis, depicted in Figure 3, showing the impact of these parameters. Notably, only a singular parameter is altered in each analysis iteration, maintaining constancy across all other parameters. Between these parameters, it seems that Hs, Y1, and Y2 cause S33, S31, and S32, respectively, to shift. Figure 4 illustrates the distribution of the electric fields on the SIW channels at 14 GHz (low-frequency band) and 17 GHz (high-frequency band) of the diplexing network. In this case, the mechanism's topology can be comprehended. If port 1 is excited in the low-frequency band, the RF signal first propagates in SIW channel 1. After that, the propagated signal is vertically transitioned by the proposed transition. Once the signal is propagated into the vertical transition, port 3 becomes active. In this configuration, no RF signal propagates into SIW channel 2. Channels 1 and 2 are thus isolated from one another. If port 2 is excited in the high-frequency band, the RF signal is transmitted in SIW channel 2, and it enters the proposed vertical transition at the end of channel 2. After that, it reaches the vertical transition, and port 3 becomes active. In this configuration, no RF signals pass through SIW channel 1. Channel 1 and channel 2 are, therefore, again isolated. Likewise, by exciting port 3 with a wide-frequency band signal, signals within SIW channels 1 and 2 are propagated across distinct frequency bands.