Prefilter

__**Prefilter**__
The first section of the circuit is the pre-filter. This is a bandpass filter designed to filter out the majority of the unwanted power in the spectrum. It is a third order filter, with an approximate passband of 2 MHz. The filter was designed using the freeware version of the Elsie program from Tonne Software. The circuit itself is shown below in Figure 4.1.1. Figure 4.1.1 – Pre-Filter Circuit

The circuit was prototyped, and its scattering parameters were gathered using the network analyzer. Figure 4.1.2 shows its gain characteristics, and Figure 4.1.3 shows its output reflection coefficient (which can be used to determine the output impedance). Figure 4.1.2 – Filter Gain Figure 4.1.3 – Prefilter Output Reflection Coefficient