Rainee N. Simons and Edwin G. Wintucky

Glenn Research Center, Cleveland, Ohio

Traveling-Wave Tube Amplifi er Second Harmonic 

as Millimeter-Wave Beacon Source for Atmospheric 

Propagation Studies

NASA/TM—2014-218121

April 2014
NASA STI Program . . . in Profi le

Since its founding, NASA has been dedicated to the 

advancement of aeronautics and space science. The 

NASA Scientifi c and Technical Information (STI) 

program plays a key part in helping NASA maintain 

this important role.

The NASA STI Program operates under the auspices 

of the Agency Chief Information Offi cer. It collects, 

organizes, provides for archiving, and disseminates 

NASA’s STI. The NASA STI program provides access 

to the NASA Aeronautics and Space Database and 

its public interface, the NASA Technical Reports 

Server, thus providing one of the largest collections 

of aeronautical and space science STI in the world. 

Results are published in both non-NASA channels 

and by NASA in the NASA STI Report Series, which 

includes the following report types:

• TECHNICAL PUBLICATION. Reports of 

completed research or a major signifi cant phase 

of research that present the results of NASA 

programs and include extensive data or theoretical 

analysis. Includes compilations of signifi cant 

scientifi c and technical data and information 

deemed to be of continuing reference value. 

NASA counterpart of peer-reviewed formal 

professional papers but has less stringent 

limitations on manuscript length and extent of 

graphic presentations.

• TECHNICAL MEMORANDUM. Scientifi c 

and technical fi ndings that are preliminary or 

of specialized interest, e.g., quick release 

reports, working papers, and bibliographies that 

contain minimal annotation. Does not contain 

extensive analysis.

• CONTRACTOR REPORT. Scientifi c and 

technical fi ndings by NASA-sponsored 

contractors and grantees.

• CONFERENCE PUBLICATION. Collected 

papers from scientifi c and technical 

conferences, symposia, seminars, or other 

meetings sponsored or cosponsored by NASA.

• SPECIAL PUBLICATION. Scientifi c, 

technical, or historical information from 

NASA programs, projects, and missions, often 

concerned with subjects having substantial 

public interest.

• TECHNICAL TRANSLATION. Englishlanguage translations of foreign scientifi c and 

technical material pertinent to NASA’s mission.

Specialized services also include creating custom 

thesauri, building customized databases, organizing 

and publishing research results.

For more information about the NASA STI 

program, see the following:

• Access the NASA STI program home page at 

http://www.sti.nasa.gov

• E-mail your question to help@sti.nasa.gov

• Fax your question to the NASA STI 

Information Desk at 443–757–5803

• Phone the NASA STI Information Desk at

 443–757–5802

• Write to:

 STI Information Desk

 NASA Center for AeroSpace Information

 7115 Standard Drive

 Hanover, MD 21076–1320
Rainee N. Simons and Edwin G. Wintucky

Glenn Research Center, Cleveland, Ohio

Traveling-Wave Tube Amplifi er Second Harmonic 

as Millimeter-Wave Beacon Source for Atmospheric 

Propagation Studies

NASA/TM—2014-218121

April 2014

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Prepared for the

International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting

sponsored by the Institute of Electrical and Electronics Engineers

Memphis, Tennessee, July 6–12, 2014
Acknowledgments

The support from the 2012 NASA GRC Center Innovation Fund (CIF) is gratefully acknowledged.

Available from

NASA Center for Aerospace Information

7115 Standard Drive

Hanover, MD 21076–1320

National Technical Information Service

5301 Shawnee Road

Alexandria, VA 22312

Available electronically at http://www.sti.nasa.gov

Level of Review: This material has been technically reviewed by technical management. 

This report contains preliminary fi ndings, 

subject to revision as analysis proceeds.
NASA/TM—2014-218121 1 

Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave 

Beacon Source for Atmospheric Propagation Studies 

Rainee N. Simons and Edwin G. Wintucky 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Abstract 

This paper presents the design and test results of a CW 

millimeter-wave satellite beacon source, based on the second 

harmonic from a traveling-wave tube amplifier and utilizes a 

novel waveguide multimode directional coupler. A potential 

application of the beacon source is for investigating the 

atmospheric effects on Q-band (37 to 42 GHz) and V/W-band 

(71 to 76 GHz) satellite-to-ground signals. 

1.0 Introduction 

Because of increasing congestion in available spectrum at 

the currently used frequency band (3 to 30 GHz) for space-toground data communications, there is now an effort by NASA, 

other United States Government agencies and the commercial 

broadband satellite communications industry to develop the 

millimeter-wave (mm-wave) frequency band for this purpose. 

The mm-wave band includes frequencies in the Q-band (37 to 

42 GHz) and the V/W-band (71 to 76 GHz). Prior to the use of 

these frequency bands for space communications, it is 

necessary to first rigorously characterize the many 

atmospheric effects, including rainfall, cloud coverage and 

gaseous absorption, on RF signal propagation from a spacebased beacon source. For high data rate wide band 

communications, it will also be necessary to characterize the 

group delay effects. The design of any operational satellite 

communication system is intimately tied with the results of the 

propagation studies. 

In the past, NASA Glenn Research Center (GRC) pioneered 

the development of Ka-band (20 to 30 GHz) communications 

by deploying the Advanced Communications Technology 

Satellite (ACTS) (Refs. 1 and 2). The ACTS served as a test 

bed in space for several of the new technologies needed for an 

operational Ka-band system. In addition, the ACTS 

propagation experiments were instituted to investigate the 

effect of Earth’s atmosphere on the propagation of Ka-band 

satellite signals (Ref. 1). 

In this paper, we present the design and test results of a CW 

satellite beacon source, based on the second harmonic from a 

space traveling-wave tube amplifier (TWTA). The keyenabling component is a rugged, easily constructed, more 

efficient waveguide based multimode directional coupler 

(Ref. 3) that extracts the second harmonic signal from the RF 

output of a high power space TWTA (Ref. 4). The application 

of the beacon source is for atmospheric propagation studies at 

Q-band and V/W-band frequencies leading towards the design 

of robust space-to-ground satellite communications links. A 

Q-band space TWTA is presently under development at L-3 

Communications Electron Technologies Inc., under a contract 

from NASA GRC. 

2.0 Beacon Architecture 

A simplified schematic of the beacon source is presented in 

Figure 1. 

2.1 Waveguide Multimode Directional 

Coupler Design 

The waveguide multimode directional coupler used in the 

test demonstration is designed and fabricated from two 

sections of dissimilar waveguides, a primary or larger cross 

section waveguide for the fundamental frequency and a 

secondary or smaller cross section waveguide for the second 

harmonic as illustrated in Figure 2. The two waveguides are 

joined together and share a common wall. In the primary 

waveguide, the signal at the fundamental frequency 

propagates as the dominant TE10 mode. However, the power in 

the second harmonic signal propagates as higher order modes. 

If an aperture is cut in the shape of a narrow rectangular slot 

parallel to the y-axis along the primary waveguide narrow wall 

the coupling to the TE10 mode will be negligibly small. 

However, the slot aperture will couple strongly to the TM11

type higher order mode. Thus the power in the second 

harmonic signal is selectively coupled to the secondary 

waveguide and can be amplified to the power level needed for 

atmospheric propagation studies. 

2.2 Multimode Directional Coupler 

Fabrication 

For the initial proof-of-concept (POC) demonstration, the 

primary and the secondary waveguides were chosen as the 

WR-62 and WR-28, respectively. Thus, the fundamental 

frequency is at Ku-band (13.25 to 18 GHz) and the second 

harmonic is at Ka-band (26.5 to 36 GHz). Figure 3 shows the 

fabricated POC multimode directional coupler used in the 

demonstrations. 
NASA/TM—2014-218121 2 

2.3 Multimode Directional Coupler Test Data 

Figure 4 shows the test setup used for the measurement of 

power at the second harmonic frequencies at the Ka-band 

secondary waveguide output port of the multimode directional 

coupler, when the TWTA is operating at saturation and 

maximum efficiency. The measured power at the second 

harmonic frequencies over a broad range extending from 27.0 

to 30.0 GHz is shown in Figure 5. The test data indicates that 

there is a significant amount of power in the second harmonic. 

Typically, beacons used in radio wave propagation studies are 

narrow band sources (Ref. 1). Hence, a desired beacon signal 

frequency can be selected from the above range of frequencies 

and amplified to the desired EIRP level (Ref. 5). It is worth 

mentioning that the fundamental signal is below the cutoff 

frequency of the Ka-band secondary waveguide and hence 

propagates unperturbed in the Ku-band primary waveguide, 

which is a major advantage over traditional harmonic filters. 
NASA/TM—2014-218121 3 

3.0 Conclusions 

The design, fabrication and characterization of a novel 

waveguide multimode directional coupler is presented. An 

application of the coupler is in a space borne beacon source 

for atmospheric propagation studies at millimeter-wave 

frequencies. 

References 

1. R. Bauer, “Ka-band Propagation Measurements: An 

Opportunity with the Advanced Communications 

Technology Satellite (ACTS),” Proc. IEEE, vol. 85, no. 6, 

pp. 853–862, June 1997. 

2. R.J. Acosta, R. Bauer, R.J. Krawczyk, R.C. Reinhart, 

M.J. Zernic, F. Gargione, “Advanced Communications 

Technology Satellite (ACTS): Four-Year System 

Performance,” IEEE Jour. Selected Areas in 

Communications, vol. 17, no. 2, pp. 193–203, Feb. 1999. 

3. Patent Application Filed with the U.S.P.T.O. 

4. R.N. Simons, J.D. Wilson, and D.A. Force, “High power 

and efficiency space traveling-wave tube amplifiers with 

reduced size and mass for NASA missions,” 2008 IEEE 

MTT-S International Microwave Symposium Digest, pp. 

319–322, Atlanta, GA, June 15–20, 2008. 

5. R.N. Simons and E.G. Wintucky, “Q-Band (37–41 GHz) 

Satellite Beacon Architecture for RF Propagation 

Experiments,” 2012 IEEE Antennas and Propagation 

International Symposium Digest, Chicago, IL, July 8–14, 

2012. 
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and

maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including

suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite

1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it

does not display a currently valid OMB control number.

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

1. REPORT DATE (DD-MM-YYYY)

01-04-2014

2. REPORT TYPE

Technical Memorandum

3. DATES COVERED (From - To)

4. TITLE AND SUBTITLE

Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source

for Atmospheric Propagation Studies

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Simons, Rainee, N.; Wintucky, Edwin, G.

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

WBS 295670.01.04

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

John H. Glenn Research Center at Lewis Field

Cleveland, Ohio 44135-3191

8. PERFORMING ORGANIZATION

 REPORT NUMBER

E-18863

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

10. SPONSORING/MONITOR'S

 ACRONYM(S)

NASA

11. SPONSORING/MONITORING

 REPORT NUMBER

NASA/TM-2014-218121

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified-Unlimited

Subject Category: 17

Available electronically at http://www.sti.nasa.gov

This publication is available from the NASA Center for AeroSpace Information, 443-757-5802

13. SUPPLEMENTARY NOTES

14. ABSTRACT

This paper presents the design and test results of a CW millimeter-wave satellite beacon source, based on the second harmonic from a

traveling-wave tube amplifier and utilizes a novel waveguide multimode directional coupler. A potential application of the beacon source is

for investigating the atmospheric effects on Q-band (37 to 42 GHz) and V/W-band (71 to 76 GHz) satellite-to-ground signals.

15. SUBJECT TERMS

Telecommunications; Space communication; Satellite communications; Microwave transmission

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

 ABSTRACT

UU

18. NUMBER

 OF

 PAGES

10

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email:help@sti.nasa.gov) a. REPORT

U

b. ABSTRACT

U

c. THIS PAGE

U 19b. TELEPHONE NUMBER (include area code)

443-757-5802

Standard Form 298 (Rev. 8-98)

Prescribed by ANSI Std. Z39-18