A frequency multiplier with active linearly tapered slot antennas (LTSA's) has been demonstrated at the second harmonic frequency. In each antenna element, a GaAs monolithic microwave integrated circuit (MMIC) distributed amplifier is integrated with two LTSA's. The multiplier has a very wide bandwidth and large dynamic range. The fundamental-to-second harmonic conversion efficiency is 8.1 percent. The spatially combined second harmonic signal is 50 dB above the noise level. The design is suitable for constructing a large array using monolithic integration techniques

Lee, Richard Q.

Simons, Rainee N.

English

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NASA Technical Memorandum 106494
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Spatial Frequency Multiplier with Active Linearly
Tapered Slot Antenna Array
Rainee N. Simons
Sverdrup Technology, Inc.
Lewis Research Center
Brook Park, Ohio
and
Richard Q. Lee
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio
Prepared for the
1994 IEEE MTT-S International Microwave Symposium
sponsored by the Institute of Electrical and Electronics Engineers
San Diego, California, May 23-28, 1994
NASA
https://ntrs.nasa.gov/search.jsp?R=19940019835 2020-06-16T16:57:36+00:00Z
SPATIAL FREQUENCY MULTIPLIER WITH ACTIVE LINEARLY TAPERED SLOT ANTENNA ARRAY
Rainee N. Simons
Sverdrup Technology, Inc.
Lewis Research Center Group
Brook Park, Ohio 44142
and
Richard Q. Lee
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135
ABSTRACT
A frequency multiplier with active linearly tapered slot
antennas (LTSAs) has been demonstrated at the second
harmonic frequency. In each antenna element, a GaAs
monolithic microwave integrated circuit (MMIC) distributed
amplifier is integrated with two LTSAs. The multiplier has a
very wide bandwidth and large dynamic range. The
fundamental-to-second harmonic conversion efficiency is 8.1
percent. The spatially combined second harmonic signal is
50 dB above the noise level. The design is suitable for
constructing a large array using monolithic integration
techniques.
INTRODUCTION
The power output of solid state devices decreases as
the frequency of operation increases. Hence to obtain high
power at millimeter wave frequencies, the power outputs from
several devices, such as, IMPATT diodes, Gunn diodes,
MESFETs or HEMTs, have to be combined using either
conventional power combiners or quasi-optical power
combiners (1). The quasi-optical power combining techniques
that have been reported include spatial amplifiers, such as
grid amplifiers using MESFETs (2), spatial frequency
multipliers using varactor diodes (3), and harmonic combiners
using FETs (4). Quasi-optical power combiners have higher
combining efficiencies over conventional power combiners
because of lower conductor losses and larger dimensional
tolerances with the absence of resonant waveguide cavities.
In addition, integrating both antennas and devices on a single
semiconductor wafer simplifies the array construction.
This paper presents for the first time frequency
multiplication and space power combining with an GaAs
monolithic microwave integrated circuit (MMIC) distributed
amplifier and an array antenna. In this approach an array of
LTSAs (5) and GaAs MMIC distributed amplifiers (6)
receives signal at a fundamental frequency, and after
multiplication and amplification, radiates the second harmonic
signal into free space. The advantages of using a distributed
amplifier are a very large gain-bandwidth product and good
input and output impedance match at both the fundamental
frequency and the harmonic frequencies, and the advantages
of using a LTSA are wide bandwidth, high gain and simple
construction. In addition, unlike spatial oscillator array, the
spatial multiplier array does not require injection locking for
coherence and stability. However, it does require a high power
source at the fundamental frequency for good conversion
efficiency.
SPATIAL ACTIVE MULTIPLIER FABRICATION AND
CHARACTERISTICS
The experimental three-element active array module is
shown in Fig. 1. The array elements are constructed by
integrating a GaAs MMIC distributed amplifier between two
nonplanar LTSAs.
GaAs MMIC Distributed Amplifier
The GaAs MMIC distributed amplifier was developed
by Texas Instruments for NASA Lewis Research Center (6).
A photograph of the amplifier chip is shown in Fig. 2. The
MMIC consists of six 300 pm wide by 0.5 µm long MESFETs
and is 1.25 mm x 2.63 mm x 0.1 mm. The bias network is
incorporated on the chip. The amplifier typically has a linear
gain of 5 ±1 dB over the frequency range of 2 to 22 GHz
with a power output of 0.5 W under large signal operation
(Drain voltage V d = 5.0 V, Drain Current Id = 570 mA, and
Gate voltage V9 = 0 V). The power added efficiency at
0.5 W is 14 percent (6).
Linearly Tapered Slot Antenna
The feed system of the nonplanar LTSA consists of a
conventional microstrip with the ground plane tapered to form
a balanced microstrip. The strip conductors of the balanced
microstrip are gradually flared with respect to the antenna
axis to form the nonplanar LTSA (5). A photograph of the
nonplanar LTSA is shown in Fig. 3. The antenna fabricated
on a 0.508 mm RT-5880 Duroid substrate (e t = 2.2) has a
measured gain of 11 dB at 20 GHz and return loss of better
than 10 dB over the frequency range of 10 to 30 GHz.
EXPERIMENTAL RESULTS AND DISCUSSIONS
Experimental Set-up
A simple phased locked measurement setup has been
developed to measure the second harmonic generated by the
spatial multiplier. In the test setup which is shown in Fig. 1,
the LTSAs at the input terminals are space-fed from a
X-Band waveguide horn antenna while those at the output
terminals radiate into free space. The free space radiation is
picked up by a K-Band waveguide horn antenna which is
placed at a far field distance from the array. To establishes
good isolation between the transmitting and receiving horn
antennas, the two horn antennas are orthogonally polarized
but the LTSAs are oriented to have the same polarization as
their respective horn antennas. In addition, the waveguide
feed dimensions of the receiving horn antenna are such that
the transmitting frequency is far below cutoff. The signal
received by the second horn antenna is fed to a balanced mixer
which is followed by a narrow band IF amplifier. The local
oscillator (LO) of the mixer is phased locked to the
transmitting oscillator resulting in good signal-to-noise ratio
and also elimination of spurious responses.
Second Harmonic Generation
The amplifiers were characterized before being inserted
into the array. The conversion efficiency, TI, of the
fundamental frequency(fo)-to-second harmonic frequency
(2fo) was determined from the measurements of the power
output, Pou t , at 2fo and the power input to the amplifier, Pin,
at fo. Experimentally it was observed that when the amplifier
was biased in the nonlinear region (V d = 2.15 V, Vg = 0 V),
the Pou , at 2fo was a maximum. This is because at V g = 0 V,
the input signal drives the gate of the MESFET into forward
conduction and hence the gate capacitance and the
transconductance varies nonlinearly with the gate voltage.
These nonlinear elements generate the second harmonic
signal. The drain bias in each of the three MMICs was adjusted
to produce a coherent output. Figure 4 shows the measured
Pou t as a function of fo at a fixed Pin of 0 dBm. The relatively
constant Pou t at 2fo over the input frequency (fo) range of 2 to
10 GHz demonstrates the wide-band characteristics of the
multiplier. Pout is a maximum at about fo = 9.3 GHz.
Figure 5 shows the measured Pout as a function of Pin at a
fixed frequency of 9.3 GHz. The results that P out increases
from about -40 dBm to 0 dBm as Pi t, increases from -10 dBm
to 10 dBm demonstrate the wide dynamic range of the
multiplier. The maximum q is about 8.1 percent which occurs
when Pin = 10 dBm. The above measurements were carried
out using a HP 8672A Synthesized Signal generator and a
HP 8566B Spectrum Analyzer.
Spatial Combining
To demonstrate spatial combining, the LTSAs at the
amplifier input were excited at fo and the amplified 2fo signal
radiated from the array was received by the horn antenna.
The measured E- and H-Plane radiation pattern of the horn
antenna at 2fo with the amplifier turned ON is shown in
Fig. 6. Also shown is the noise pattern when the amplifier is
turned OFF. The 2fo signal is 50 dB above the noise.
CONCLUSIONS
A wide bandwidth and large dynamic range spatial
frequency multiplier with GaAs distributed amplifiers and
LTSAs has been demonstrated. The maximum is about 8.1
percent. The amplitude of the 2fo signal is 50 dB above the
noise level.
REFERENCES
1. K. Chang, and C. Sun, "Millimeter-wave Power-com-
bining techniques," IEEE Trans. Microwave Theory
Tech., Vol. MTT-31, No. 2, pp. 91-107, Feb. 1983.
2. M. Kim, J.J. Rosenberg, R.P. Smith, R.M. Weikle, J.B.
Hacker, M.P. DeLisio, and D.B. Rutledge, "A Grid
Amplifier," IEEE Microwave Guided Wave Lett.,
Vol. 1, No. 11, pp. 322-324, Nov. 1991.
3. C.F. Jou, W.W. Lam, H.Z. Chen, K.S. Stolt, N.C.
Luhmann, Jr., and D.B. Rutledge, "Millimeter-Wave
Diode-Grid Frequency Doubler," IEEE Trans. Micro-
wave Theory Tech., Vol. 36, No. 11, pp. 1507-1514,
Nov. 1988.
4. S. Kawasaki, and T. Itoh, "40 GHz Quasi-Optical Sec-
ond Harmonic Spatial Power Combiner Using FETs
and Slots," 1992 IEEE MTT-S Inter. Microwave Symp
Digest, pp. 1543-1546, June 1-5, 1992.
5. R.N. Simons, and R.Q. Lee, "Nonplanar Linearly
Tapered Slot Antenna with Balanced Microstrip Feed,"
IEEE Antennas and Propagation Society Inter. Symp.
Digest, Vol. IV, pp. 2109-2112, 1992.
6 "20 GHz Monolithic Power Amplifier Module Devel-
opment," Texas Instruments Final Technical Report,
Contract No. NAS 3-23781.
X-band
horn
antenna
MMIC
distributed TSA
amplifiers
LTSA	 /
K-band
horn	 /
antenna
E
E
R Far
field
/distance
L
F --- --------r / - 1	 10 mHz phase lock
Mixer	 '7')
	
reference signal
IF amp
^ 	 I
F
'	 Receiver
Figure 1.—Schematic illustrating an experimental setup for
frequency multiplication and space power combining.
Figure 2.—GaAs MMIC distributed amplifier chip mounted on a
heat sink and wire bonded to 50 11 microstrip lines on alumina at
the input and output ports.
C-92-26081
Figure 3.—Nonplanar linearly tapered slot antenna on duroid in a
test fixture.
Signal
source
X0.5 cm
3
f
^ ca -10
O N
E^>:-15
	 00CO Co UD aci	 0	 0	 O	 0	 00
c Q -2000 0o- 0
2 -25
0	 2	 4	 6	 8	 10
Fundamental frequency, fo (GHz)
Figure 4.—Measured second harmonic output power as a
function of fundamental frequency at a fixed input power
of 0 dBm.
0
0
c^ —10
Oc
N7Q
N
P —20
c
0
E
Co
r
c
0
L) -30
V)
EM0
o -40
o_
-50 1	 1'
-15 -10	 -5	 0	 5	 10	 15
Pin (dBm) at fundamental frequency, f o-
Figure 5.—Measured second harmonic output
power as a function of input power at a fixed
fundamental frequency of 9.3 GHz.
Amplifier
0
On
- — Off
-10
-20
Co0
m -30
E -40
Q
-50	 ---	
-------------- --------------
-------------- ------
	 -
(a)
-70
-90 -75 -60 -45 -30 -15 0 15 30 45 60 75 90
Angle, deg
0
-10
-20
m
-30
E -40
-50	 ----- -u^,L " u ------- ---	 '---"'--	 ----
(b
-70
-90 -75 -60 -45 -30 -15 0 15 30 45 60 75 90
Angle, deg
Figure 6.—Measured radiation pattern of the horn antenna
showing space power combining at the second harmonic
frequency of 17.9 GHz. (a) E-plane. (b) H-plane.
I
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1. AGENCY USE ONLY (Leave blank) 2. REP ORT DATE 3. REPORT TYPE AND DATES COVERED 
February 1994 Technical Memorandum
4. TITLE AND SUBTITLE 5. FUNDING NUMBERS
Spatial Frequency Multiplier with Active Linearly Tapered Slot Antenna Array
WU-506-44-2C6. AUTHOR(S)
Rainee N. Simons and Richard Q. Lee
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
REPORT NUMBER
National Aeronautics and Space Administration
Lewis Research Center E-8060
Cleveland, Ohio 44135-3191
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
National Aeronautics and Space Administration
Washington, D.C. 20546-0001 NASA TM-106494
11. SUPPLEMENTARY NOTES
Prepared for the 1994 IEEE MTT-S International Microwave Symposium sponsored by the Institute of Electrical and Electronics Engineers, San
Diego, California, May 23-28, 1994. Richard N. Simons, Sverdrup Technology, Inc., Lewis Research Center Group, Brook Park, Ohio 44142
(work funded by NASA Contract NAS3-25266), presently at NYMA, Inc. Engineering Services Division, 2001 Aerospace Parkway, Brook Park,
Ohio 44142 and Richard Q. Lee, NASA Lewis Research Center. Responsible person, Richard Q. Lee, organization code 5640, (216) 433-3489.
12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE
Unclassified - Unlimited
Subject Category 33
13. ABSTRACT (Maximum 200 words)
A frequency multiplier with active linearly tapered slot antennas (LTSAs) has been demonstrated at the second
harmonic frequency. In each antenna element, a GaAs monolithic microwave integrated circuit (MMIC) distributed
amplifier is integrated with two LTSAs. The multiplier has a very wide bandwidth and large dynamic range. The
fundamental-to-second harmonic conversion efficiency is 8.1 percent. The spatially combined second harmonic
signal is 50 dB above the noise level. The design is suitable for constructing a large array using monolithic integra-
tion techniques.
14. SUBJECT TERMS 15. NUMBER OF PAGES
6
Spatial frequency multiplier; Linearly tapered slot antenna; Array antenna 16. PRICE CODE
A02
17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT
OF REPORT OF THIS PAGE OF ABSTRACT
Unclassified Unclassified Unclassified
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Spatial frequency multiplier with active linearly tapered slot antenna array

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