Meeting summary


Quick recap
The meeting focused on two main presentations: Al's reception of Artemis II signals and Jim's propagation research updates. Al shared his experience tracking the Artemis II spacecraft using a 5-meter dish, successfully receiving signals around 2216.5 MHz during the mission's lunar orbit phase, despite challenging conditions and early morning operations. Jim presented updates on his team's millimeter-wave propagation research, highlighting significant improvements to their predictive modeling tools through collaboration with Graham McIntire, Joe Jareka, and Mike Lavelle. The team expanded their dataset to include 58,000 contest QSOs and 18,500 commercial link measurements, developing new applications including a path calculator and propagation mapping tools that provide real-time predictions for 902 MHz through 241 GHz bands. The discussion included technical details about atmospheric ducting, antenna heights, and the challenges of predicting long-distance millimeter-wave propagation.

Next steps
Eric: Mail two slimline dish bolts to David (address provided in chat), and David to send PayPal payment to Eric as thanks.
Graham: Add functionality to allow users to edit or flag invalid contacts in the propagation database, including ability to update antenna height and grid location.
Graham: Add feature to allow filtering/searching contacts by callsign on the contact map to facilitate data review and cleanup.
Graham: Add support for beacons with multiple modes in the beacon submission form.
Graham: Investigate and implement toggle between flat and curved Earth view for path profile display.
Graham: Continue development of beacon monitoring receivers (SDR-based) for 24/7 data collection and integration into the propagation model.
Jim/NTMS leadership: Submit micro-grant proposal to Irving Club for 47 GHz beacon funding.
NTMS: Approve and send $300 donation to ARRL Spectrum Defense Fund.
Jim: Make arrangements to deliver new 47 GHz beacon to Al (or coordinate with Al for pickup/delivery).
NTMS team: Consider and plan for antenna tune-up party (specific date to be confirmed, possibly May 25th), focusing on 122 GHz or other bands as appropriate.
NTMS team: Continue encouraging submission of non-contest contacts and beacon reception reports to improve propagation model data.
Graham: Add ability for users to mark contacts as rain scatter, EME, or other propagation modes in the database for better data categorization.
Graham: Investigate integration/leverage of rain scatter algorithms (e.g. from mrainscatter.com) for historical contact analysis.
NTMS team: Continue outreach for permanent 24/7 beacon monitoring sites and coordinate with interested parties.
NTMS team: Consider scheduling and planning for next in-person meeting at David's location.
Summary
SDR Equipment Comparison Discussion
Al and NTMS_Zoom_Host discussed SDR equipment options, specifically comparing the HackRF and Pluto devices. NTMS_Zoom_Host recommended the HackRF based on his experience, noting its advantages despite limitations in duplex operation and receive/transmit channel capabilities. They also tested audio transmission through the Zoom platform, confirming that audio signals could be heard through a headset monitor but not effectively through the microphone. The conversation concluded with NTMS_Zoom_Host preparing to demonstrate 47GHz beacon signals during what appears to be a technical presentation.

High-Voltage Connector Technical Discussion
The meeting began with participants introducing themselves and discussing weather conditions across different locations. Barry shared his experience with technical issues related to high-voltage connectors in his equipment, which he attributed to a carbon path problem. Al and Barry discussed their experiences with similar issues and shared tips on maintaining and cleaning connectors. The conversation also touched on the challenges of receiving signals beyond 180 degrees due to geographical obstructions and the growing interest in 24GHz communications.

Technical Discussion and Presentation Setup
The meeting began with informal discussions about mail delivery experiences and tax preparation. David requested help finding specific bolts for a slimline dish, and Eric offered to provide them. The group discussed technical details about the bolts and their length requirements. 

Artemis II Mission Tracking Experience
Al discussed his experience tracking the Artemis II mission using his 5-meter dish, sharing details about the technical setup and challenges involved. He explained his use of tracking websites like n2yo.com and Unistellar to determine the spacecraft's location, noting some inaccuracies in the altitude calculations. Al described his efforts to build a down-converter to receive the signal at 2216.5 MHz, using a filter provided by Kent, and his attempts to observe the signal using a spectrum analyzer. He mentioned the work of other amateur radio operators, including Alex K6QXY and CT1BYM, who had successfully tracked the mission and shared their findings.

Artemis Mission Signal Monitoring
Al presented his experience monitoring the Artemis mission's signal around the moon using a home-built converter and receiver. He successfully detected the beacon signal at 2216 MHz with a noise figure of 3 dB and achieved a signal-to-noise ratio of up to 30 dB. Al noted the clean spectrum in the 13-centimeter band and discussed plans for future monitoring, including potentially using a HackRF and external filtering. Pete has offered to present on his team's work using a 28-foot dish and HackRFs at a future meeting.

Space Mission Tracking Technical Discussion
The group discussed technical details about a recent space mission tracking project, including ERP specifications and antenna information. Barry shared that the transmitter was 10 watts with an EIRP of 49 dBm, though the exact antenna details remained unclear. Bob mentioned that the amateur community, including the Deep Space Exploration Society, was involved in tracking the mission using GPS systems and provided Doppler shift information to confirm the spacecraft's location. The discussion concluded with recommendations for EME (Earth-Moon-Earth) contacts, with Al suggesting that 1296 MHz and 10 GHz bands offer the most activity, particularly noting that 1296 MHz would be easier to access with a smaller dish.

Propagation Tool Development Updates
The meeting focused on updates to a propagation tool development project, with significant contributions from team members including Graham McIntire, Joe Jareka, and Mike Lavelle. The team discussed their progress from a surface-based model with 7 scoring elements to incorporating more advanced atmospheric data through skew-T plots and radiosonde observations. They reviewed various applications developed, including a link budget analyzer and contact occurrence tracker, while noting that these have been largely superseded by newer developments. The discussion concluded with plans to monitor real-time beacon reports and identify triggers for potential "truck rolls" (field deployments) based on stable weather conditions.

Millimeter Wave Propagation Analysis Updates
The meeting focused on discussing recent improvements and new applications in millimeter wave propagation analysis for amateur radio. Graham McIntire significantly expanded the dataset by incorporating 18,500 commercial link measurements and additional weather data sources, increasing the analysis criteria from 7 to 10 factors. The team demonstrated new tools, including a path calculator and live propagation maps covering the continental U.S. at high resolution, which provide hourly updates and score propagation conditions across multiple frequency bands from 902 MHz to 241 GHz.

Propagation Tool Analysis Meeting
The group discussed propagation conditions using a path calculator tool at different frequency bands including 10GHz, 24GHz, and 47GHz. They examined how the tool calculates path loss, margin, and propagation scores based on weather data and antenna heights. Graham explained that more beacon data is needed to improve the machine learning model's accuracy, as current data heavily weighs on contest periods. The discussion also covered how the tool provides weather mapping capabilities and propagation predictions, with participants exploring how different frequencies perform under various conditions.

Radio Contact Database System Review
The team discussed a database system for tracking radio contacts and beacon information. Graham explained the meteorological data being used in the project and demonstrated how to input beacon information, including frequency, location, and technical specifications. The group reviewed the contact map feature, which shows real-time data and allows for precise location tracking using either 6-digit or 10-digit grids. Mike suggested adding user editing capabilities to improve data quality, which Graham agreed to implement, noting that currently only he and Jim have admin access.

Earth Curvature Display Issues Discussion
The team discussed issues with the Earth curvature display in their mapping system, with Graham clarifying that the algorithm properly accounts for Earth's curvature despite display limitations. They identified a data error in Paul's contest contact where the grid square was incorrectly recorded, likely due to a transcription error in the original log submission. Mike suggested adding a filter to show contacts involving specific stations to enable crowd-sourced data validation, which Graham noted could be implemented through the existing search functionality. The discussion concluded with a reminder that while models have limitations, they should be evaluated based on their usefulness in guiding decision-making rather than perfect accuracy.

High-Frequency Propagation Modeling Improvements
The group discussed improving propagation modeling for high-frequency communications, particularly focusing on ducting phenomena and data collection methods. Graham explained his work on collecting signal data from beacons to train models, noting that current contest data primarily covers 10 GHz and above during specific contest periods. The team discussed the potential benefits of continuous beacon monitoring using SDR receivers, which could provide more detailed signal strength data across different weather conditions. They also explored the possibility of monitoring both horizontal and vertical polarization, though current data and equipment primarily focus on horizontal polarization. The discussion concluded with a brief mention of rain scatter contacts and the need for better classification of different contact types in their database.

Rain Scatter Analysis and Beacon Design
The team discussed implementing a rain scatter analysis feature for contact submissions, with Graham explaining that historical weather data is already collected and could be used to identify potential rain scatter events. Mike suggested collaborating with a researcher at rainscatter.com to apply existing algorithms to historical data. The group also reviewed a new beacon project design based on the tri-band beacon RF deck, which includes 10 GHz, 24 GHz, and 47 GHz capabilities with GPS functionality. The beacon's design features were detailed, including the use of RF0, WA1MBA board, and quadrupler components, with specific attention to frequency calculations and power levels. The beacon can operate for up to three days on a 100-watt panel solar system and includes a GPS module for location tracking.

47 GHz Beacon System Demonstration
Jim demonstrated a new 47 GHz beacon system with remote control capabilities via cell phone app, showing how it can transmit CW signals and be controlled remotely to turn different RF components on and off. The group discussed upcoming events including a potential antenna tune-up party, and agreed to make a $300 donation to the ARRL Spectrum Defense Fund. Graham confirmed that the new 47 GHz beacon will be located at his house (EM13SF) similar to where AA5C's 24 GHz beacon is located.

NTMS April 11 2026 meeting