We propose to design a reflectionless high-pass filter for a load-pull test measurement setup that provides high RF transmission coefficients between 2.3 GHz and 6 GHz while suppressing out-of-band reflections for frequencies below 2.3 GHz. The reflectionless property of the proposed filter ensures signal integrity and protection to the device under test in industry-standard RF characterization setups such as load-pull measurements. After creating a simulation model, a physical filter will verify that the filter works as intended (i.e., within the target specifications).