Paul Christopher, Satellite Communications Consultant, President PFC Associates

*** ******* **, **

Leesburg, VA 20175

703-***-****

ad31r4@r.postjobfree.com

Jan 2007- present

Summary:

I have over five decades of analytical experience in satellite communications and terrestrial communication, with key analysis done at MITRE Corp.(Bedford) for the late W.T. (Bill) Brandon and satellite analysis for A H Jackson (NASA Code 533) while at Stanford Telecom and Odyssey. My current emphasis is millimeter wave and laser communications for worldwide satellite communication.

My research in 2011-2018 has included large area ground arrays for 10.6 micron satellite-ground laser communication (IEEE ICSOS 2011, AIAA SPACE 2011, Ka and Broadband Conference 2011) . Link availability is expected to exceed 85% for large areas of the Northern Temperate Zone. Specially modified Molniya satellite orbits (Brandon Orbits) are anticipated to be attractive for laser satellite communication. The Ka Conference 2011, 2012 and 2015 recognized the complementary nature of optical and 30 GHz communication links, with 30 GHz links providing reliable communication in difficult areas like Miami.

My research in the 2000-2016 period has spanned 960 MHz -140 GHz millimeter communication links. It included laser papers for IEEE Energy Tech 2012 (below) and 2013, Ka 2015 (Bologna). and Ka 2016 (Cleveland). Current papers include optimum frequencies for ground terminals for Earth Observation Satellites, typically in the 15- 100 GHz bands, and attractive millimeter wave bands and IR are emphasized.

The 2019- 2022 period emphasized satellite laser communication to the Arctic/

We also had a productive period from 2009 to 2018.

Further analysis on the inclined elliptic Brandon Molniya orbits revealed that they are quasi-stationary for several hours near their apogee over the Northern Hemisphere. This allows a New York or London ground observer to look straight up at a nearly fixed spot in the sky, for the same kind of advantage that an equatorial observer has with geosynchronous satellites. This allows the New York observer to use much higher frequencies.

I presented a paper on the Brandon Molniya orbit at the June 2009 ISCCS conference in Edinborough.

Further high frequency advantages appeared, and I presented a satellite laser communication paper at Ka 2010 in Milan.

We had requests from an ITU working group to examine adjacent band interference into GPS receivers from a new group of cell phone towers proposed by L3 Communication. I used my 2008 Wireless Conference paper (Virginia Tech) to show, in 2012, that the massive number of cell phone towers would cause intolerable interference in GPS receivers.

The Brandon Molniya orbits had other key advantages. They could carry solar arrays in space to beam down 10 micron laser beams for terrestrial power in the Temperate Zone. It would be especially valuable in northern latitudes and Denver. I presented papers at Energy Tech 2012 and 2013.

In the same period I developed and presented ‘Ka and Millimeter Waves for Reliable Satellite Communication in Florence, Italy (2013).

In 2014 we were besieged with queries about the suitability of 70-100 GHz satellite communication.

James Nessel of NASA Glenn and I developed a paper on 70-100 GHz communication and presented it at the Italian Ka 2015 Conference.

The advantages of solid state silicon laser devices were becoming apparent: I presented a silicon laser satellite for downlink beams at Advanced Functional Materials Conference, Stoneybrook 2015

More reliability was desired for laser communication. I analyzed wider area for the U.S. and Europe, and presented the paper at Ka Cleveland, Oct. 2016.

In 2017 we were concerned with communication to reentry vehicles Prior communication with Apollo 13 had failed badly for four minutes. We examined the problem and found that 30- 40 GHz is attractive for reentry vehicles.

We were concerned with a range of laser wavelengths in 2018. We examined the one to 10.6 micron range. We favored 10.6 microns at the Ka1018 conference (Niagara Falls, Oct 2018). but found that 6 microns could be very competitive for satellite-aircraft.

The language Mathematica was valuable in every paper, and we strive to keep up with new versions

Prior Positions:

Odyssey Systems Consulting, Technical Director Electronic Engineering Support

Summary:

I developed new equations for attenuation on millimeter wave and IR satellite links. These equations were useful in the Sept. 06 Ka Satellite Conference for a description of attenuation on lunar relay links. I filed for a patent on methods for IR satellite communication links, and also derived new satellite communication attenuation maps which were useful for frequencies ranging from a few GHz to 100 GHz.

I developed new statistical methods for radar performance in the presence of co-channel GPS interference, and developed new VHF-UHF interference results from UWB devices.

I have provided the technical evaluation and development of input supporting national level spectrum management policy decisions, and have over 40 publications.

Relevant Activities and Results:

Jun 01- Jan 07

I assisted the Technical Director of AFFMA in the protection and expansion of available Air Force and DOD radio spectrum, with activities to support the AFFMA director as:

-Perform Ultra Wideband (UWB) analysis and recommendations, with analysis of link equations and atmospheric attenuation, analysis of FCC UWB mask for GPS, UWB interference effects in the Air Force Satellite Communication Network (AFSCN), and analysis and programming of vehicular UWB effects in the satellite 30/20 GHz band. I developed new equations for aggregate interference which applied to VHF and UHF links.

-Perform GPS spectrum analysis and comparison with European GALILEO spectrum use to evaluate compatibility, by evaluating joint spectrum integrals.

-Examined GPS sensitivity to JTIDS, and found that GPS is insensitive to the JTIDS pulse rate.

-Performed RNSS interference sensitivity analysis to large interference arrays near airports. The interference analysis is being used at the RTCA WG 6 to anticipate interference into GPS L1.

-Analyze interference distances and required coordination distances for satellite ground stations and radar, as a function of elevation angle, transmitter power, antenna gain pattern, and frequency (Milcom2001). The results were used to support studies in ITU Working Group 4a.

-Evaluate multipath fading with the aid of Reed and Russell’s complex reflection coefficients for long propagation paths over the earth, and write programs to predict performance over airborne communication links.

-Found new Fourier Transforms for signal and radar waveforms.

Senior Engineer Oct 89 – May 01; I supported Stanford Telecom and the Naval Electromagnetic Spectrum Center and has played a key role in supporting US study groups that are preparing positions for the World Radiocommunications Conference (WRC) 2003. Developed interference analysis tools that accurately measure the potential interference between radars and satellites to support the frequency allocation process. Provided radar/satellite analyses illustrating and quantifying the interference potential to satellite transmissions. Responsible for the concept development and analysis of optimum satellite communication relay positions.

Project Engineer Nov '83Oct 89; Provided Systems Engineering and Support (SEAS) to NASA Code 533 Tracking and Data Relay Satellite(TDRS) activity. I derived (optimum beamwidth/tracking error) relations to minimize long term Bit Error Rate (BER) which fell into several areas, as (1) orbital analysis for satellite communications, (2) propagation analysis, (3) optimum frequency derivations, and (4) jamming analysis. I filled this need by analyzing modified Keplerian orbits, placing antennas with complete antenna patterns on the satellite, and writing programs.

Associate Research Engineer, Research Engineer Jul '73- Oct '83;

This was a key period of satellite analysis for the Air Force at MITRE Bedford (’73-’86) and test of electromagnetic compatibility at IIT Research Insitute for the Navy (’61-‘64). We developed new results for satellite communication at MITRE, which included both propagation analysis and orbit analysis.

IITRI was concerned with Navy electromagnetic interference. The Navy had intense shipboard interference related to high power radar emissions from rotating antennas. At first, we dealt with these emissions deterministically; i.e., we used fixed antenna patterns complete with sidelobes and backlobes to find interference. We recognized that radar antenna patterns may often be represented closely as Gaussian when scanned in azimuth. We analyzed random interference, and found that it would deliver a lognormal probability density function to the Temco Correlator.

Education:

- Muskingum College ('52'55) BS Math ('57)

- Penn State ('55'57) BS Mech Eng ('57)

- Johns Hopkins ('58'60) grad PhysicsGilman Fellowship

- Johns Hopkins ('70'72) MA Biophysics('72), and all PhD course requirements

Selected Publications:

P Christopher, “Satellite Solar Arrays, with Laser Ground Links with Brandon Orbits-,“

Proc. IEEE EnergyTech 2012, Cleveland OH, May 31, 2012

--, “Modified Molniya Orbits for Solar Power Arrays,” Proc. AIAA Guidance & Navigation

Conference, Minneapolis, Aug 14 2012.

-- “Reliable Millimeter Wave Satellite Communication with Transition to Lasers,”

Cyber Journal, August, 2012.

-- “Considerations for Lunar Relays, with Millimeter Wave and IR

Communications,” Proc. Twelfth Ka Band Utilization Conference, Naples, Italy,

Sept. 28, 2006.

--, “Optimum Communication and Surveillance Frequencies for Atmospheric Reentry Vehicles,” Classified Proc. Milcom 2004, Monterey, Nov. 2004.

--, “Coordination of Terrestrial and Satellite Systems, with Bullington’s

Tropospheric Reflection Model,” Proc. Milcom, Washington, Oct. 2001.

--, “Worldwide Infrared and Millimeter Wave Satellite Communication

Comparisons,” SPIE Laser Conference, San Jose, CA, Jan. 2001.

--, “Satellite Orbits for Ka Band Communication,” Ka Band Conference,

Cleveland, June, 2000.

--, "Aggregate Ultra Wideband Interference in Satellite

Communications,” Proc. Ka Band Conference, Vicenza Italy, Oct. 2004.

--, (currently preparing Draft chapter on Communication with Hypersonic Vehicles,

INTECH Publishers)

[Also several satellite laser and millimeter wave publications 1981- 2014 available]

Additional references;

Satellite Solar Array with Laser Downlink to Denver, EnergyTech 2013, Cleveland.

Ka and Millimeter Waves for Reliable Satellite Communication with Diversity, Ka Florence 2013.

(coauthor) Mid Millimeter Wave Satellite Communication 70-100 GHz, with Ground Site Diversity Ka 2015, Italy.

Satellite Solar Array with Silicon Laser Downlink to Denver and the Arctic, Advanced Functional

Materials, Stoneybrook 2015

Communication with Lunar Rentry Vehicle ongoing work 2017

Satellite- Aircraft Internet Laser Communication, Ka Niagara Falls, Oct. 2018

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