High-Frequency Signal Strength Simulation at GRAPE Personal Space Weather Stations Using PHaRLAP Ray Tracing

High-frequency (HF) radio wave propagation serves as both a vital communication tool and a probe for ionospheric behavior. This work models and analyzes the reception of HF signals from the standard transmitting station WWV (Fort Collins, Colorado) to two well-calibrated Personal Space Weather Stations (PSWS): W2NAF (Scranton, Pennsylvania) and K6KPH (Point Reyes, California). These stations are equipped with Great Radio Amateur Propagation Experiment (GRAPE) receivers—GPS-disciplined systems designed to measure standard time signals with high precision. To simulate HF wave propagation, we use the Provision of High-Frequency Raytracing Laboratory for Propagation Studies (PHaRLAP), a MATLAB toolbox for ionospheric ray tracing. Utilizing the data-based International Reference Ionosphere (IRI) 2020 model, which supplies the ionospheric background conditions, we analyze HF propagation at 5, 10, and 15 MHz by launching a fan of rays at varying elevation angles to determine which rays successfully reach the receivers. In addition, we are extending our simulations using the Python-based SAMI3 ionospheric model. We also compute ionospheric HF absorption and compare the modeled values with the observed signal strengths recorded by the PSWS throughout the day, aiming for the predicted absorption to be within one order of magnitude of the observations. This work enhances our understanding of how ionospheric absorption affects HF signal strength across different times of day and seasons, thereby contributing to space science, space weather research, and amateur radio science.