Author:  Tom Hagen

Title: Portable VLF Receiver for Making Calibrated Magnetic Field Strength Measurements

Abstract: This presentation is about the author's continuing efforts to get calibrated measurements of the field strengths of the various VLF stations used by the SuperSID program as reference sources to detect sudden ionospheric disturbances (SID’s). Presently, the amplitude of data coming in from the various SuperSID stations around the world is uncalibrated. When a SID is detected, there is a measurable change in relative signal strength, but actual field strengths are unknown. If a portable VLF receiver and loop antenna setup could be developed that is calibrated, then such a setup could be shipped to different sites for calibrated field strength measurements.  Users could even build their own receiver and loop antenna from standard plans. A small loop design and two receiver designs are discussed.  Estimated sensitivities of each receiver design are calculated. Calculations are verified with laboratory tests.

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Author: Curt Kinghorn

Subject:  One of the following:  1.  Converting drift scan lines from one of my radio telescopes to a full-fledged sky map/image.  This is proving more challenging than I initially thought but the final product is also proving to be more rewarding in that the results looks more like what the sky would look like if I were looking at in through "radio-eyes."

2.  Inserting a time delay in one leg of an interferometer to get "steering" without having to move the antenna (sort of analogous to phased-array radar)!

3.  Comparing the results of my 611 MHz radio telescope using an ICOM R7000 receiver with that same system only with a FunCube Dongle Software Defined Radio receiver.  (So far, the ICOM is the undisputed champion but I am hoping to improve the performance of the SDR system!)

4.  Converting a commercial satellite antenna positioner (used by commercial TV station remote units to send their remote signals to the "home" station) to (much more precisely!) aim the antenna for either my 611 MHz or my 12.2 - 12.7 GHz radio telescope antennas.

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Author: Whitham D. Reeve, Anchorage, Alaska USA, SARA Member

Title: Sudden Frequency Deviations Due to Solar Flares

Abstract: This paper describes the interesting phenomena of Sudden Frequency Deviations (SFD), which are changes in the received frequency of a fixed carrier caused by rapid changes in Earth’s ionosphere from a solar flare. For purposes of this study I recorded WWV and WWVH time service signals received at Anchorage, Alaska USA between early June and end of December 2014. Part I describes the concepts of sudden frequency deviations in terms of solar flares and ionospheric propagation, and Part II describes the instrumentation and observations during the study period.

WWV and WWVH transmit continuous radio frequency carriers with very high accuracy and stability on 2.5, 5, 10 and 15 MHz. WWV also transmits on 20 MHz and in April 2014 restarted transmitting on 25 MHz. The transmitted carrier frequencies are accurate to a few parts in 10¹³ (about 0.000 000 000 000 3 Hz), but the short-term accuracy is degraded to a few parts in 10⁹ during normal propagation to distant receivers. Sudden frequency deviations lasting a minute or more due to solar flares can be two or three orders of magnitude worse.

Two ionospheric conditions are attributed to sudden frequency deviations, both caused by the x-ray and extreme ultra-violet (EUV) energy released by a solar flare and reaching Earth a little more than 8 minutes later. First, a slab of ionosphere below the reflection region undergoes a rapid change in refraction index and, second, the ionosphere’s reflection region undergoes a rapid vertical movement. Both conditions change the propagation path length and introduce a Doppler shift in the radio wave. Either one or both can cause a sudden frequency deviation. It is interesting to note that sudden frequency deviations are correlated with solar flares but due to the variability in the spectral content of flares at x-ray and EUV wavelengths, only a fraction of all flares cause an SFD.

The method of detecting sudden frequency deviations described here is quite sensitive (the weakest x-ray flare detected in the study period was C1.8) and the technique may be helpful in verifying sudden ionospheric disturbances (SID) at very low frequencies. SFDs were studied extensively in the 1960s but there appears to have been little work since then.

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Author:  Dean Knight

Title: A Student’s Hands-on Introduction to Radio and Radio-astronomy

Abstract: The engaging introduction to radio electronics for students can involve the construction, modification and testing of a tunable (VHF/UHF) solar radio telescope of a tweeked Jove dual-dipole design, incorporating a simple 1 transistor circuit, common household materials and Radio-SkyPipe. Students are able to easily experiment (and establish controls) with the parameters of a radio telescope, thus allowing them to explore the effects of these modifications on both the observed frequency and amplitude of the processed incoming radio signal.

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Author: Ken Redcap (KR5ARA)

Title: 611 MHz Total Power Radio Telescope - Part 0x03 (Software)

Author: Ray Fobes (W1OTH)

Title: The Dipole Array Radio telescope (DART)

Abstract: The radio astronomy observatory at Embry-Riddle Aeronautical University, Prescott is in the process of designing and installing a cross-dipole phased array radio telescope.  The principal purposes of this telescope are to provide students with a research grade radio telescope for enhancing their space physics and astronomy curriculum as well as performing long term pulsar timing in support of programs like LIGO.

Based on the low frequency demonstrator of the original Mileura Widefield Array (now at the Murchison Widefield Array) we will be building a three tile, 110 – 300 MHz phased array telescope with direct sampled rf and signal processing in the digital domain. 30 MHz of bandwith can be directly sampled from each of the tiles simultaneously. Each tile will have up to 10 m² collecting area with maximum gain in the 200-250 MHz region, ideal for pulsar monitoring. Rapid all sky pointing above 30 deg in both polarizations will be available.

In addition to characterizing the radio sky and tracking pulsar timing the telescope will also be available for long term solar research including the heliopause as well as passive and active ionospheric studies.

This presentation will describe the design and construction of the DART telescope.

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Author: Tushar Sharma, Dhruv Bhaskar ,Ramzi Darraji, Fadhel Ghannouchi

Electrical and Computer Engineering Department

University of Calgary, Canada

tsham@ucalgary.ca

Title: Radio Jove Instrumentation and Education Outreach

Abstract: This paper looks into the effect of varying parameters on different antenna designs with an aim to achieve an optimized antenna design that can be used with the Radio Jove kit. As a team of amateur radio astronomers, we have simulated the response of different antennae on Numerical Electromagnetic Code – 2 which uses the method of moments solution of the electric field integral equation and the magnetic field integral equation for closed, conducting surfaces. By varying the geometries (height above ground, diameter of loops, lengths of dipoles, tuning capacitors etc.) of antenna structures, we have observed how different parameters affect gain, directivity, V.S.W.R. and thus the cumulative efficiency of antennae. It is quite apparent that many minute factors play a key role in determining antenna performance. All the antenna designs have been optimized for a frequency of 20.1 MHz, which is the operating frequency of the Radio Jove setup. The Radio JOVE kit makes use of a dipole antenna which is relatively huge in size (because of the operating frequency of 20.1 MHz). Another aim of our research is to reduce the overall antenna size while maintaining performance. Simulation results have proved that a loop antenna poses as a potential substitute, as it can be constructed fairly easily and for a low cost.

While experimental results are under way, we present the data collected from simulations in this paper. This data will provide an insight into the different factors affecting antenna response and can potentially lead to an optimized, easy – to – use Radio JOVE kit. With setting up of Astronomical Teacher training Institute in Alberta, Canada we have introduced different programs including STAR , Summer Grant with IEEE MTT chapter, Winter Grant and Student-Mentor .With collaboration with IEEE to support student activities in field of Radio Science and engineering future goals are setting up of amateur observatories in school across Alberta.

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Author: Jack Welch, UC Berkeley Graduate School

Title: Low Noise Feeds for the Allen Telescope Array

Abstract: The goals for the Allen Telescope Array (ATA) antennas are low background noise and wide bandwidth.  To achieve the low background pick-up from the ground, the antenna optics uses an offset Gregorian secondary.  To achieve the wide bandwidth, a log-periodic antenna is used for the feed.  The log-periodic feed is tapered with its shortest operating wavelength give by the dimension of its small end, and its longest wavelength given by size of the large end.  For the ATA. The range is 0.9 GHz to 15 GHz; four octaves.  At any particular frequency in that range, the active portion of the feed is relatively small.  One awkward feature for the log-periodic is that all wavelengths are received from the direction of the small end, and the input terminals for the low noise amplifier must be at the small end.  The receiver box must be fitted within the large end of the log-periodic structure with coaxial cables extended to the tip.  To avoid losses in these cables and in the feed, the entire structure is cooled to 70K.  The input amplifier produces very little noise at that temperature. Achieving the low physical temperature requires that the feed and receiver be enclosed in a transparent bottle.  The low background of the Gregorian optics and the cooled amplifier and feed combine to deliver very low system temperatures for the array. The forty-two antennas of the ATA are currently being outfitted with these new receiver systems, thanks to a generous donation from Franklin Antonio.

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Author: Jon Richards, SETI Institute

Title: The Signal Search at the Allen Telescope Array

Abstract: This presentation will provide an overview the Allen Telescope Array (ATA), located in Northern California. The ATA is the instrument the SETI Institute's Center for SETI Research uses to search for extraterrestrial radio signals. The ATA has 42 radio dishes, each 20 feet in diameter able to detect signals between 1GHz and 10GHz. Jon will cover how the SETI signal search program works, what hardware is used, how the signals are detected, as well as review the current state of the effort. There will also be a discussion of the beginning efforts to use commercial software defined radio devices to aid in several aspects of operations.

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Author: Leif Svalgaard

Title: "Radio, Ionosphere, Magnetism, and Sunspots"

Abstract: When Marconi in 1902 demonstrated radio communication across the Atlantic Ocean at a distance of 2000 miles it became clear that an electric 'mirror' existed high in the atmosphere to guide the radio waves around the curvature of the Earth. Kennelly and Heaviside independently suggested that a layer of ionized gas, the 'ionosphere' at an altitude of 60-100 miles was responsible for the effect, but it was only more than two decades later that the existence of such a layer was firmly established by the British scientist Appelton for which he received the 1947 Nobel Prize in Physics. Physicists long resisted the idea of the reflecting layer because it would require total internal reflection, which in turn would require that the speed of light in the ionosphere would be greater than in the atmosphere below it. It was an example of where the more physics you knew, the surer you were that it couldn't happen. However, there are two velocities of light to consider: the phase velocity and the group velocity. The phase velocity for radio waves in the ionosphere is indeed greater than the Special Relativity speed limit making total internal reflection possible, enabling the ionosphere to reflect radio waves. Within a conducting layer electric currents can flow. The existence of such currents was postulated as early as 1882 by Balfour Stewart to explain a the diurnal variation [discovered in 1722] of the Earth's magnetic field as due to the magnetic effect of electric currents flowing in the high atmosphere, such currents arising from electromotive forces generated by periodic (daily) movements of an electrically conducting layer across the Earth’s permanent magnetic field. Today, we know that solar Extreme Ultraviolet radiation is responsible for ionizing the air and that therefore the ionospheric conductivity varies with the solar cycle [e.g. as expressed by the number of sunspots]; so, observations of the Sun are vital in monitoring and predicting radio communications for Amateurs and Professional alike. Conversely, centuries-long monitoring of variations of the Earth's magnetic field can be used to determine long-term variations of solar activity. The talk weaves these various threads from multiple scientific and engineering disciplines together to show the unity of scientific endeavor and its importance for our technological civilization.

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Author: Maria Spasojevic, Stanford University

Title:  Quantifying the Role of Wave-Particle Interactions in Controlling the Dynamics of the Earth's Radiation Belt

Abstract: The Earth's radiation belts are comprised of highly energetic ions and electrons that are trapped in Earth encircling orbits as a result of the dipolar configuration of the geomagnetic field. The electron flux in the outer radiation belt is particularly dynamic and can vary by several orders of magnitude in the timescale of hours to days. This intense and highly variable radiation poses a significant risk to satellites and astronauts in space. There have been significant advances in the past decade in understanding which physical processes are important in controlling the dynamics of the belts during solar-driven geomagnetic disturbances. What remains to be quantified is where, when, and under what conditions, specific processes are active and to what degree they individually contribute to the overall balance of acceleration and loss. Increasing attention has been paid to the role of wave-particle interactions in accelerating electrons up to very high energies. This talk will focus on a particular plasma wave known as whistler-mode chorus emissions. There is evidence that chorus-driven acceleration plays a major and possibly dominant role in the reformation of the outer belt in the aftermath of geomagnetic storms. However, a significant confounding factor is that wave-particle interactions involving chorus can also result in significant losses of electrons due to scattering. We will highlight recent advances in quantifying the role of chorus in radiation belt dynamics.

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Author: Philip Scherrer, Prof Physics, Stanford University

Title: Viewing the Sun, Inside and Out, with SDO"

Abstract: The Solar Dynamics Observatory (SDO) has been gathering data since its launch (5 years ago). SDO's goals include learning if solar activity is predictable and if so, how to do it. SDO carries three experiments, the Extreme ultraviolet Variability Experiment (EVE), the Atmospheric Imaging Assembly (AIA), and the Helioseismic and Magnetic Imager (HMI).  EVE measures Sun-as-a-star spectra in the extreme ultraviolet to monitor wavelengths that are important for space weather impacts on the Earth.  AIA obtains images in 7 EUV, 2 UV, and 1 visible bands to study processes in the low corona.  HMI measures photospheric motions to enable helioseismology and photospheric magnetic fields to enable connecting the interior to the corona. In this talk I will give a brief overview of SDO and the HMI and AIA data products.  I will describe some of the recent findings from HMI concerning the solar interior and evolving magnetic activity in more detail.

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