@proceedings {937, title = {Radio Wave and GPS Scintillation Impacts of the 10 May 2024 G5 Geomagnetic Storm Observed at the United States Military Academy}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

Beginning on 7 May 2024, a sequence of nine CMEs erupted from solar active region 3664, with several merging together in transit through the solar wind towards Earth. The first combined CME impacted the dayside magnetosphere on 10 May and triggered an extreme G5 geomagnetic storm. The storm commenced at 16:37 UTC on 10 May, reached maximum intensity at 03:33 UTC on 11 May, and persisted into recovery through May 13. An array of instruments were online throughout the Hudson River Valley during the event, including scientific grade GPS receivers, amateur radios, Personal Space Weather Stations and a ground magnetometer. The Hudson Valley is located in the mid-latitude region and ranges from just upstate of New York City in Yonkers, NY to as far north as Troy, NY. At these mid-latitudes, the storm induced beautiful red and green auroral activity, amplitude and phase scintillation of GPS signals, flare- and storm-induced radio blackouts within the amateur radio bands, plasma density modifications, geoelectric and geomagnetic field perturbations, plasma flows, etc. Here we examine primarily the radio wave, scintillation and ground magnetic impacts of this geomagnetic storm as observed over West Point.

}, author = {Jason Derr and Joanna Halfhill and Diana Loucks and Stephen Hamilton} } @proceedings {967, title = {Radio Wave Propagation and Antenna Fundamentals}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {
This tutorial gives a basic overview of radio propagation and the fundamentals of antennas. Topics include
The Nature of Radio Waves, Dipole Antenna Characteristics, Line of Sight Propagation, Diffraction and Multipath Interference, What a BALUN does, The Isotropic Antenna and Concept of Gain, Examples of Gain Producing Antennas and How They Work, Transmission Line Basics, and Selected Antenna Stories.\ 
}, author = {Steve Cerwin} } @proceedings {944, title = {The Role of the Polar Vortex in Atmosphere-Ionosphere Coupling}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

In the polar regions, the wintertime polar vortices play a critical role in "bottom-up" atmosphere-ionosphere coupling via the generation and modulation of atmospheric gravity waves (GWs) and via interactions with planetary waves (PWs). This talk will first present a tutorial on the polar vortex: why it forms, where and when it exists, and variability in vortex strength sub-seasonally (within each winter), inter-annually (from winter-to-winter), and inter-hemispherically (in the Arctic and Antarctic). I will then present the current state of understanding regarding the role of the polar vortex in coupling different atmospheric layers via {\textquotedblleft}bottom-up{\textquotedblright} processes. In the last decade it has become widely accepted that PW-driven sudden stratospheric warmings (SSWs) cause variability in the thermosphere-ionosphere system. Recent results demonstrate that strong polar vortex events result in variability of the opposite sign than is observed during SSWs. In addition, the geographic distribution of smaller-scale GWs depends on the strength and shape of the polar vortex. The polar vortices act to vertically couple the atmosphere from the troposphere to geospace by changing the background wind field through which GWs propagate. Recent work demonstrates that localized jet cores around the polar vortex also act as a middle atmosphere source for GWs. Vortex modulation and generation of atmospheric GWs then impact the abundance of traveling ionospheric disturbances that may impact Ham radio communications.

}, author = {V. L. Harvey} } @proceedings {849, title = {On the ray tracing block of a sky wave over-the-horizon radar simulation tool}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

A simulation tool of a sky wave over-the-horizon radar performance and detection process includes many stages based on different models, which creates a synthetic searching scenario as a first step followed by a digital signal processing to detect and locate a potential target. The whole process involves several concatenated physical mechanisms which depend on OTHR specific properties. They can be modeled as quasi-independent blocks to analyze synthetic scenarios in order to define the radar{\textquoteright}s characteristics and range of operation which are essential when selecting radar{\textquoteright}s operating parameters in order to achieve the best performance. In this work a sensitivity analysis of the ray tracing block is performed. This block is implemented as an independent block in the simulation tool and estimates the signal propagation path with an adapted Jones \& Stephenson ray tracing code. This code has options for: (1) the electron density profile, which can be chosen from analytical models or the IRI-2016 model, (2) the Earth{\textquoteright}s magnetic field from the IGRF-12 model, which can be turned on and off, and (3) collision frequencies, which can also be turned on and off. From this ray tracing we obtain the two-way delay of the signal travelling between the transmitter and the target, the ground range distance and azimuth relative to the transmitter. The sensitivity analysis is carried out analyzing this block output{\textquoteright}s\ variation as a consequence of changes in its main input factors. This study is useful to dimension features and elements of a real radar, and also to determine the needs of in-situ ionosphere sounding.

}, author = {Zenon Saavedra and Ana G. Elias} } @proceedings {868, title = {Ray-trace modelling of diurnal variation in two-hop sidescatter propagation}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Two-hop sidescatter, an off-great circle propagation mode enabling above-the-basic-MUF communications, is identified by low SNR and high spectral spread (width between -3 dB points). Observable at 7 MHz and above, as a daytime mode it enables propagation from 10s km to 100s km. Additionally, it may appear before, and or after, great-circle one-hop propagation as it operates with a lower F2 layer critical frequency. We have devised a computationally efficient modelling approach for two-hop sidescatter using 3D ray tracing. First, ray landing spots from a transmitter are found over 360{\textdegree}\ azimuth and a sensible range of elevations. Second, the process is repeated for a transmitter at the receiver. The key assumption is that reciprocity holds sufficiently to avoid the computationally demanding need to place a transmitter at every transmitter ray landing spot. A scattering metric, the product of the number of landing spots from transmitter and pseudo-transmitter in a 1{\textdegree}x1{\textdegree}\ area, is a useful approximation to the location and strength of the sidescatter. The off-great circle scattering location from the model has been verified by a rotating-antenna experiment at 14 MHz on paths from Northern California to Utah and Oregon using FST4W digital mode. The diurnal variations of sidescatter location and strength are particularly interesting for a meridional transmitter and receiver geometry: morning (local time) scatter from the east, from land on the California to Oregon path, with afternoon through nighttime scatter from the west, from the ocean. We discuss a qualitative comparison of hourly model simulations with signal level and circuit reliability data from FST4W spots. The nighttime minimum in both parameters is pronounced in the observations and model. An afternoon dip in circuit reliability, without reduction in signal level, is tentatively explained by the model showing strongest scatter alternating between east and west before settling to the west. We postulate that severe multipath scatter from both east and west, land and ocean, sufficiently increased frequency spread to reduce probability of decode for the ~6 Hz bandwidth FST4W mode. This study illustrates the usefulness of combining 3D ray tracing with purposeful observations to explain an underappreciated propagation mode.

}, author = {Gwyn Griffiths and Devin Diehl and R. Lynn Rhymes and Frederick Wahl} } @proceedings {873, title = {Reexamining the Characteristics of Flare-Driven Doppler Flash using multipoint HF Observations}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Sudden enhancement in the ionospheric electron density following a solar flare causes disruption in the transionospheric high frequency (HF: 3-30 MHz) communications, commonly referred to as Shortwave Fadeout (SWF). This disruption is also recorded as a sudden enhancement in Doppler frequency in the received HF signal, referred to as Doppler Flash. This phenomenon was recorded and reported by the SuperDARN HF radar network. Previous investigations have suggested that among various phases of flare-driven SWFs observed by HF radars Doppler Flash is the first to observe, and there are no significant trends in Doppler Flash with location, operating frequency, or flare intensity. Recent development showed that Doppler observations from the distributed HamSCI Personal Space Weather Station (PSWS) can provide insight into the physics behind changes in phase path length of the trans ionospheric radio signals. Unlike SuperDARN, HamSCI PSWS can record the full phase of the Doppler Flash, provide an edge to revisit the characterization study and compare with existing dataset. In this study, we demonstrate how HamSCI observations can be used to infer flare-driven changes in ionospheric properties. We found: (1) HamSCI PSWS has higher dynamic range than SuperDARN during flare making it less susceptible to SWF, thus it can record the full Doppler Flash; (2) data from HamSCI PSWS shows a strong function trend with flare strength, operating frequency, and location on the Earth; and (3) HF rays traveling longer distances experienced statistically higher Doppler. We understand that, while instantaneous Doppler realized by the HF signal is proportional to the rate of change in solar irradiance, the total Doppler realized is proportional to the total flare-deposited energy in the ionosphere.

}, author = {Shibaji Chakraborty and Kristina V. Collins and Nathaniel A. Frissell and J. Michael Ruohoniemi and Joseph B. H. Baker} } @proceedings {839, title = {Results from the 2023 SEQP and GSSC}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Presenting operating results from the Solar Eclipse QSO Party and the Gladstone Signal Spotting Challenge, two of the HamSCI Festival of Eclipse Ionospheric Science events held concurrently with the October 14, 2023 annular solar eclipse over North and South America.\  Details on how to participate in the next running of both events, to be held during the April 8, 2024 total solar eclipse over North America, will be given.

}, author = {Gary Mikitin} } @proceedings {876, title = {Reworking the MUSIC Algorithm to Mitigate MSTID Direction Estimation Bias Associated with SuperDARN Radar Field-of-View Geometry}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Medium Scale Traveling Ionospheric Disturbances (MSTIDs) are variations in the F region ionospheric electron density. MSTIDs can be associated with atmospheric gravity waves (AGWs) and provide critical information for understanding the ionosphere, which is an electrically charged region of the atmosphere. Previous SuperDARN studies of MSTIDs have used the Multiple Signal Classification (MUSIC) algorithm to determine the size, speed, and direction of these disturbances in the ionosphere. Upon analyzing MSTID MUSIC results from ten North American SuperDARN radars over a period of twelve winter seasons (2010-2022), we found a bias in the SuperDARN MSTID MUSIC direction estimation algorithm that preferentially reports waves as traveling along the boresight direction of the radars. We demonstrate that this bias is caused by the radar Field-of-View geometry and report on the progress algorithm development for removing this bias.

}, author = {Michael Molzen and Thomas Pisano and Nicholas Guerra and Juan Serna and Nathaniel A. Frissell} } @proceedings {752, title = {A Review of "Climatology of Medium Scale Traveling Ionospheric Disturbances Observed by the Midlatitude Blackstone SuperDARN Radar"}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, abstract = {

This poster is a review of Frissell et al. (2014) by undergraduate students for the purpose of learning about SuperDARN and MSTIDs as part of a
research project to study the differences between MSTIDs observed in the Northern and Southern Hemispheres.

Frissell, N. A., Baker, J. B. H., Ruohoniemi, J. M., Gerrard, A. J., Miller, E. S., Marini, J. P., West, M. L., and Bristow, W. A. (2014), Climatology of medium-scale traveling ionospheric disturbances observed by the midlatitude Blackstone SuperDARN radar, J. Geophys. Res. Space Physics, 119, 7679{\textendash} 7697, doi:10.1002/2014JA019870.

}, author = {Nicholas Guerra and Michael Molzen and James Fox and Juan Serna and Nathaniel A. Frissell} } @conference {609, title = {The Radio JOVE Project 2.0}, booktitle = {HamSCI Workshop 2022}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, organization = {HamSCI}, address = {Huntsville, AL}, abstract = {

Radio JOVE is a well-known public outreach, education, and citizen science project using radio astronomy and a hands-on radio telescope for science inquiry and education. Radio JOVE 2.0 is a new direction using radio spectrographs to provide a path for radio enthusiasts to grow into citizen scientists capable of operating their own radio observatory and providing science-quality data to an archive. Citizen scientists will have opportunities for presenting and publishing scientific papers. Radio JOVE 2.0 uses more capable software defined radios (SDRs) and spectrograph recording software as a low-cost ($300) radio spectrograph that can address more science questions related to heliophysics, planetary and space weather science, and radio wave propagation. Our goals are: (1) Increase participant access and expand an existing radio spectrograph network, (2) Test and develop radio spectrograph hardware and software, (3) Upgrade the science capability of the data archive, and (4) Develop training modules to help a hobbyist become a citizen scientist. We will overview Radio JOVE 2.0 and give a short demonstration of the new radio spectrograph using the SDRplay RSP1A receiver with a dipole antenna and the associated Radio-Sky Spectrograph (RSS) software.

}, author = {C. Higgins and S. Fung and L. Garcia and J. Thieman and J. Sky and D. Typinski and R. Flagg and J. Brown and F. Reyes and J. Gass and L. Dodd and T. Ashcraft and W. Greenman and S. Blair} } @proceedings {641, title = {Ray Tracing in Python Utilizing the PHaRLAP Engine}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

Provision of High-Frequency Raytracing Laboratory for Propagation (PHaRLAP) is an ionospheric ray tracing library developed by the Australian Department of Defence (DOD). PHaRLAP is freely available as a MATLAB toolbox downloadable from an Australian DOD website. PHaRLAP is capable of numerically ray tracing radio propagation paths using 2D and 3D algorithms through model ionospheres, most typically the International Reference Ionosphere (IRI). In an effort to make PHaRLAP available to a wider user community we are porting the PHaRLAP MATLAB toolbox to the open source Python 3 language while retaining the original core PHaRLAP computational engine. In this presentation, we describe the architecture of the new Python 3 PHaRLAP interface and demonstrate examples of 2D ray traces using the new interface.

}, author = {Alexander Calderon and William Liles and Nathaniel Frissell and Joshua Vega} } @proceedings {485, title = {RJOVER: An alternative approach using SDR technology to reduce costs for the NASA Radio JOVE citizen science effort}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, abstract = {

The NASA-run citizen science project, Radio JOVE, utilizes widespread distribution of single and dual-dipole antenna receiving stations to study the magnetic interactions between Jupiter and its moon, Io. The citizen science effort has been well established and maintained since 1998, and the Radio JOVE project team has streamlined kit distribution and assembly documentation for amateur data collectors and hobbyists. The antennas, receiver, software, and related components are available for purchase in kits that range in price from depending on the level of {\textquotedblleft}pre-assembly{\textquotedblright}. For instance, we estimate that the prices of un-assembled and fully assembled kit receivers are approximately $95 and $225, respectively. Establishing a Radio JOVE receiving station is no small task, and these prices are reasonable and appropriate. To further data collection accessibility and broaden the participating audience, however, we seek to further reduce these costs-- specifically that of the receiver. Our primary goal is to code, integrate, and test a software-defined radio (SDR) receiver for Radio JOVE data collection to verify whether the technology could be a less expensive alternative to the original distributed kit receiver. By coordinating with the Case Western Reserve University (CWRU) Research Farm, as well as with guidance from faculty in the CWRU Electrical, Computer, and Science Engineering (ECSE) department and the Radio JOVE Project Team, we hope to establish a Radio JOVE receiving station at CWRU whereupon we can test our alternative SDR receiver for Jovian signal collection. If our alternative receiver works on a level comparable to the existing kit receiver, we can offer a cheaper, more modern and digital age approach that could appeal to a wider audience including those working with a tighter budget and those who are interested in software-defined radio, all of whom simply want to help the scientific effort.\ 

}, url = {https://hamsci2021-uscranton.ipostersessions.com/?s=8D-A5-71-AF-BD-32-32-6C-C3-71-E2-59-AB-87-B0-0D}, author = {Tyler Kovach and Skylar Dannhoff and Jared May} } @article {450, title = {Rapid and Accurate Measurement of Polarization and Fading of Weak VHF Signals Obliquely Reflected from Sporadic-E Layers}, journal = {IEEE Transactions on Antennas and Propagation}, year = {2020}, abstract = {

In the E-region of the ionosphere, at heights between 90 and 130 km, thin patches of enhanced ionization occur intermittently. The electron density in these sporadic-E (Es) clouds can sometimes be so high that radio waves with frequencies up to 150 MHz are obliquely reflected. While this phenomenon is well known, the reflection mechanism itself is not well understood. To investigate this question, an experimental system has been developed for accurate polarimetric and fading measurements of 50 MHz radio waves obliquely reflected by mid-latitude Es layers. The overall sensitivity of the system is optimized by reducing environmental electromagnetic noise, giving the ability to observe weak, short-lived 50 MHz Es propagation events. The effect of the ground reflection on observed polarization is analyzed and the induced amplitude and phase biases are compensated for. It is found that accurate measurements are only possible below the pseudo-Brewster angle. To demonstrate the effectiveness of the system, initial empirical results are presented which provide clear evidence of magneto-ionic double refraction.

}, keywords = {Brewster angle, ionosphere, radio noise, Radio wave propagation, VHF}, issn = {0018-926X}, url = {https://researchportal.bath.ac.uk/en/publications/rapid-and-accurate-measurement-of-polarization-and-fading-of-weak}, author = {Chris Deacon and Witvliet, Ben A. and Cathryn Mitchell and Simon Steendam} } @article {414, title = {The Rebirth of HF}, year = {2020}, month = {05/2020}, institution = {Rohde and Schwarz}, type = {White Paper}, address = {Munich, Germany}, abstract = {

HF stands for {\textquoteleft}high frequency{\textquoteright} and is usually used to refer to signals with frequencies in the range of 3 MHz to 30 MHz, although in many cases the practical definition of HF has be extended down to frequencies as low as 1.5 MHz. HF is also sometimes referred to, somewhat loosely, as {\textquoteleft}shortwave,{\textquoteright} especially in the context of broadcasting. These HF frequencies correspond to wavelengths in the range of approximately 10 to 100 meters. Given that modern homes contain Wi-Fi access points operating in the gigahertz range and that some 5G deployments are taking place in so-called millimeter-wave bands, the names {\textquotedblleft}high{\textquotedblright} frequency and "shortwave" may seem a bit misplaced, but it is worth nothing that the first experiments in long-distance radio communication by Marconi around the year 1900 used even lower frequency signals.

One of the best-known applications of HF is worldwide or global communications. Both government and commercial broadcasters can reach listeners worldwide using HF frequencies. This global reach is also extremely useful in many government and military applications, and HF is used extensively by amateur radio operators around the world. This paper will begin with an exploration of the unique properties of HF that enable global communications.

}, author = {Paul Denisowski} } @conference {308, title = {Red Pitaya SDR Recorder for Antarctica (Demonstration)}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, author = {Frissell, Nathaniel A. and Melville, Robert and Stillinger, Andrew and Jeffer, Gil} } @conference {313, title = {A Research Quality, Low Power and Cost Magnetometer Package for use in Citizen Science (Demonstration)}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

A high precision low cost magnetometer package combining GPS time keeping, data logging, real time graphing, and wifi data distribution is under development by the Moldwin Magnetics Laboratory at the University of Michigan. The prototype collects data for use in geomagnetic sensing. The system includes a Solar panel, a 12V lead acid battery, and a charge controller. All electronics are enclosed in a weatherproof plastic case, except for the magnetometer, which is housed separately to reduce noise. Data is processed by a raspberry pi and displayed on a color HDMI LCD screen. Our goal of keeping costs low helps distribute the system to citizens to form a network of magnetometers to better monitor our environment.

}, author = {Mark Moldwin and Kit Ng and Jacob Thoma and Leonardo Regoli and Maya Pandya} } @conference {284, title = {Review of SDR Hardware for the Personal Space Weather Station}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

This presentation is a survey of currently available SDR receivers for HF use, focusing on devices aimed at the amateur radio and experimenter community at a price point of $1000 or less.\  That scope includes a lot of commercially-available radios, and it is the goal of this presentation to gather information about the characteristics of each device that are relevant to the HAMSCI requirements: frequency range; dynamic range; frequency control; possibility to timestamp samples; IQ streaming capability, and openness of development platform.\  Where applicable, additional interesting features of the devices are noted. While primarily focused on HF receivers, transceivers and units with higher frequency coverage are included where they also provide useful HF receive performance.

}, author = {J. R. Ackermann} } @article {138, title = {The Reverse Beacon Network}, volume = {100}, year = {2016}, month = {10/2016}, pages = {30-32}, issn = {0033-4812}, url = {http://www.nxtbook.com/nxtbooks/arrl/qst_201610/index.php}, author = {Pete Smith and H. W. Silver} }