A space power amplifier composed of active linearly tapered slot antennas (LTSA's) has been demonstrated and shown to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit (MMIC) three-stage power amplifier is integrated with two LTSA's. The LTSA and the MMIC power amplifier has a gain of 11 dB and power added efficiency of 14 percent respectively. The design is suitable for constructing a large array using monolithic integration techniques

Lee, Richard Q.

Simons, Rainee N.

English

NASA Technical Reports Server

NASA Technical Memorandum. 106036 _=-
..........................
_'-_pace Power Aih-p...... lificatioffW]thActive
Linearly Tapered Slot Antenna Array
Rainee N, Simons
Sverdrup Technology, Inc.
Lewis Research Center Group
Brook Park, Ohio _ _
and ....
Richard Q. Lee
National Aeronautics ond Space Administration v: _; :-_-:: -:-
Lewis Research Center _.
Cleveland, Ohio
Prepared for the
In_mational MicrowaveSympos-_urn-MTT '93 -- .............
sponsored by the Institute of Electrical and Electronics Engineers
_ __ Atlanta, Georgia, June 14-18, 1993
-- (NASA-IM-106036) SPACE POWER
........................... AMPLIFICATION WITH ACTIVE LINEARLY
..... _: TAPERED SLOT ANTENNA ARRAY
(Sw?rdrup Technology) 6 p
G3/33
N93-22485
Unclas
0151407
https://ntrs.nasa.gov/search.jsp?R=19930013296 2020-03-17T06:11:39+00:00Z

SPACE POWER AMPLIFICATION WITH ACTIVE LINEARLY
TAPERED SLOT ANTENNA ARRAY
Rainee N. Simons and Richard Q. Lee
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135
Abstract
A space power amplifier composed of active linearly
tapered slot antennas (LTSAs) has been demonstrated and
shown to have a gain of 30 dB at 20 GHz. In each of the
antenna elements, a GaAs monolithic microwave integrated
cir-cuit (MMIC) three-stage power amplifier is integrated with
two LTSAs. The LTSA and the MMIC power amplifier have
a gain of 11 dB and power added efficiency of 14 percent
respectively. The design is suitable for constructing a large
array using monolithic integration techniques.
Introduction
The power output as well as the dynamic range of
microwave solid state devices decreases as the frequency of
operation increases. Hence to obtain high power at fundamen-
tal frequencies of several tens of GHz, the output from all the
devices have to be combined using either conventional power
combiners or quasi-optical power combiners.l In the case of
conventional power combiners, the combining is done with
Wilkinson, radial line, and hybrid coupled networks. In the
case of quasi-optical combiners, oscillators constructed with
IMPATr diodes, 2 Gunn diodes, 3 MESFETs, 4 or HEMTs 5 are
integrated with microstrip patch antennas or linearly tapered
slot antennas (LTSAs) 6 to form an active antenna array which
combines power radiatively in free space. The advantages of
quasi-optical power combiners over conventional power
combiners are higher combining efficiency because of lower
conductor losses and larger dimensional tolerances with the
absence of resonance modes. In addition both antennas and
devices can be integrated on a single semiconductor wafer thus
simplifying the array construction. The disadvantage of
oscillator based quasi-optical combiners is that the individual
oscillators have to be phase locked to a reference source or the
active array has to be placed in a Fabry-Perot resonator to
produce coherent radiation.
Another way to obtain high power is to construct a
spatial amplifier. One such scheme is the grid amplifier. 7 Each
unit cell of the grid amplifier consists of a pair of packaged
GaAs MESFETs with the sources connected together to form a
differential amplifier and with the gate and drain terminals
extending radially to form a pair of orthogonal strip antennas.
Radiation to and from a planar array of identical unit cells is
quasi-optically coupled by a vertically or a horizontally polar-
ized beam respectively.
This paper presents for the first time a spatial ampli-
fier with GaAs monolithic microwave integrated circuit
(MMIC) multi-stage power amplifiers. In this approach an
array of active antenna modules constructed from nonplanar
LTSAs 8 and GaAs MMIC amplifiers receives signals at lower
power, and after amplification re-radiates signals into free
space. The two advantages of the spatial amplifier over the
spatial oscillator are that only a single stable lower power
source is required (thus greatly simplifying the combiner
construction) and that the amplifiers can be individually
optimized. Figure 1 schematically illustrates a possible
arrangement for space power amplification.
Active Antenna Module Characteristics
The experimental three-element array module is
showns chematically in Figure 2. The array elements are
constructed by integrating a GaAs MMIC multi-stage power
amplifier between two nonplanar LTSAs.
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. The design of the non-planar
LTSA and its characteristics are reported in Ref. 8. The
antenna is fabricated on a 0.02 inch thick RT-5880 Duroid
substrate. The measured gain of the LTSA is about 11 dB at the
center frequency of 20 GHz. The LTSA has a return loss S 11
of 10 dB (2:1 VSWR) over a bandwidth extending from 10 to
30 GHz.
(_A_ MMIC Multi-Stage Power Amplifier
The GaAs MMIC three-stage power amplifier was
designed and fabricated by Texas Instruments for NASA Lewis
Research Center. 9 A photograph of the amplifier chip is shown
in Figure 3. The amplifier is constructed on a GaAs substrate
with an active layer doping level of 2.5x1017 cm -3. The gate
widths of the three stages are 1.2, 2,4, and 6.0 ram, respec-
tively, and the gate length is 0.5 Wn in all the stages. The chip
size is about 4.0 by 3.0 by 0.1 ram. The bias network is
incorporated on the chip. The drain voltage V d and
current I d is 6.3 V and 1.9 A, respectively. The gate voltage
V_ is-0.6V.Themeasuredgain($21)onatip 8510B ANA
with a 40 dB coaxial attenuator on the drain side of a typical
amplifier is shown in Figure 4. The gain is greater than I0 dB
over the frequency range of 18 to 21 GHz. The saturated output
power measured on a Pacific Instruments scalar network ana-
lyzer at 20 GHz is about 1.8 W with a gain of 10 dB and power
added efficiency of 14 percent. 9
Experimental Results and Di_qus_ions
A simple measurement procedure has been developed 1.
to estimate the gain of the space amplifier. This procedure in-
volves the LTSAs at the input terminals are space fed from a
single horn antenna while those at the output terminals radi-ate
into free space. The free space radiation is picked up by a 2.
second horn antenna which is placed at a tar field distance
from the array. The ratio of the measured received power with
and without bias to the MMIC amplifiers provides an estimate
of the gain of the space amplifier. In the setup, the two horn
antennas are orthogonally polarized but the LTSAs are oriented 3.
to have the same polarization as their respective horn antennas,
thus good isolation between the transmitting and the receiving
horn antennas is established. Also, for comparison purposes, a
single LTSA was tested as a receive antenna. The H-plane
pattern is shown in Figure 5 which exhibits a power gain of 6.7
dB with the MMIC amplifier turned ON. 4.
Three-Hem¢nt Arriav Module
In this experiment, the LTSAs at the amplifier input
and output are oriented with the H and E vectors of the re- 5.
ceiving horn, respectively as shown in Figure 6(a). This
arrange-ment allows the horn to excite the three LTSAs with
equal amplitude. The measured radiation pattern is shown in
Figure 7(a) with the amplifiers turned ON and OFF, respec-
tively. The gain increases by as much as 30 dB when the
amplifiers are turned ON which is in good agreement withthe 6.
measured gain of the amplifiers.
A second experiment, as shown in Figure 6(b), is
carried out with the LTSAs at the input and output oriented
with the H and E vectors of the receiving horn, respectively. 7.
The measured radiation pattern is shown in Figure 7(b). In this
arrangement the gain increases by 25 dB when the amplifiers
are turned ON. The gain is lower in this case because the
LTSAs on either side of the center element are excited with a
lower amplitude due to the amplitude taper of the electric field 8.
distribution of the transmitting horn. The experimental three
element LTSA MMIC array module is shown in Figure 8.
Conclusions
A space power amplifier composed of active LTSA
antennas has been demonstrated and shown to have a gain of
30 dB at 20 GHz. In each of the antenna elements, a MMIC
three-stage power amplifier is integrated with two LTSAs.
The GaAs MMIC power amplifier and the LTSA have a power
added efficiency of 14 percent and a gain of 11 dB, respec-
tively. The design is suitable for constructing a large array
using monolithic integration techniques.
.
References
K. Chang, and C. Sun, "Millimeter-wave power-combining
techniques," IEEE Trans. Microwave Theory Tech.,
vol. MTI'-31, no. 2, pp. 91-107, Feb. 1983.
N. Camilleri, and B. Bayraktaroglu, "Monolithic
millimeter-wave IMPATr oscillator and active antenna,"
IEEE Trans. Microwave Theory Tech., vol. 36, no. 12,
pp. 1670-1676, Dec. 1988.
K. Chang, K.A. Hummer, and J.L. Klein, "Experiments on
injection locking of active antenna elements for active
phased arrays and spatial power combiners," IEEE Trans.
Microwave Theory Tech., vol. 37, no. 7, pp. 1078-1084,
July 1989.
J. Birkeland, and T. Itoh, "FET-based planar circuits for
quasi-optical sources and transceivers," IEEE Trans.
Microwave Theory Tech., vol. 37, no. 9, pp. 1452-1459,
Sept. 1989.
R.N. Simons, and R.Q. Lee, "Planar dielectric resonator
stabilized HEMT oscillator integrated with CPW/aperture
coupled patch antenna," IEEE MTT-S Int. Microwave
Symp. Dig., vol. I, pp. 433-436, 1992. (Also, NASA
TM-105752, pp. 21-23, 1992.)
J.A. Navarro, Y.H. Shu, and K. Chang, "Wideband integra-
ted varactor-tunable active notch antennas and power
combiners," IEEE MTT-S Int. Microwave Syrup. Dig.,
vol. III, pp. 1257-1260, 1991.
M. Kim, J.J. Rosenberg, R.P. Smith,RM, Weikle, J.B.
Hacker, M.P. DeLisio, and D.B. Rudedge, "A grid ampli-
tier," IEEE Microwave Guided Wave Lett., vol. 1, no. 11,
pp. 322-324, Nov. 1991.
R.N. Simons, and R.Q. Lee, "Nonplanar linearly tapered
slot antenna with balanced microstrip feed," IEEE
Antennas Propag. Soc. Int. Symp. Dig., vol. IV,
pp. 2109-2112, 1992.
"20 GHz Monolithic Power Amplifier Module Develop-
ment," NAS 3-23781.
2
L E A S  1 biasl power 
supply Horn antenna 7 I - "-- 
-/LLy \./. antenna 
Signal 
source 
GaAs MMlC power 
amplifiers on heat sinks 
Figure 1 .--Schematic illustrating a possible arrangement for 
space amplification. 
LTSA 7 
MMlC 
V 4 . 3 &  - Top side metalization t 
Bottom side metalization 
Figure P.--Schematic illustrating the three-element array 
module. (Ao: free space wavelength.) 
Figure 3.-GaAs MMlC three-stage power amplifier. 
18.0 18.8 19.6 20.4 21.2 22.0 
Frequency, GHz 
Figure 4.-Typical measured gain of MMlC amplifier. 
-1 0 
-40 
-501 I I I I I I 
-90 4 0  -30 0 30 60 90 
Angle, deg 
Figure 5.-The measured H-plane radiation pattern of a single 
LTSA with and without the amplifier. 
3 
Horn 
LTSA - 
Horn 
antenna 7 
-70 
(a) H-plane. 
...a. ,,..,..... Amplifier off 
I I I I I 
anrenna - 
MMlC 
AmDlifiers- Yl 
-50 
Signal 
source 
- Amplifier on 
.......II.. .. Amplifier off 
I I I I I I 
Horn 
antenna -, 
(b) E-plane. 
Figure 6.-LTSA orientation in the three-element array module 
for gain measurement. 
0 
-1 0 
-20 
-0 
a i  
3-30 c 
F 
.-  
4-40 
C-92-10642 
Figure 8.-The experimental three element LTSA MMlC array 
module. 
4 

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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE
June 1993
4. TITLE AND SUBTITLE
Space Power Amplification With Active Linearly Tapered Slot
Antenna Array
6. AUTHOR(S)
Rainee N. Simons and Richard Q. Lee
7. PERFORMINGORGANIZA'r:I'O'N'NAME(S)AND ADDRESS(ES)
Sverdrup Technology, Inc.
Lewis Research Center Group
2001 Aerospace Parkway
Brook Park, Ohio 44142
9. SPONSORING/MONITORING AGENCY NAMES(S) AND ADDRESS(ES)
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191
3. REPORT TYPE AND DATES COVERED
Technical Memorandum
5. FUNDING NUMBERS
WU-506-44-2C
8. PERFORMING ORGANIZA_ON
REPORT NUMBER
F_,--7604
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
TM-106036
11. SUPPLEMENTARY NOTES
Prepared for the International Microwave Symposium-Mq"T '93 sponsored by the Institute of Electrical and Electronics Engineers, Atlanta, Georgia,
June 14-18, 1993. Rainee N. Simons, Sverdrup Technology, Inc., Lewis Research Center Group, 2001 Aerospace Parkway, Brook Park, Ohio
44142. Richard Q. Lee, NASA Lewis Research Center. Responsible person, Rainee N. Simons, (216) 433-3462.
12a. DISTRIBUTION/AVAILABILITY STATEMENT
Unclassified-Unlimited
Subject Category 33
12b. DISTRIBUTION CODE
13. ABSTRACT (Max mum 200 words)
A space power amplifier composed of active linearly tapered slot antennas (LTSAs) has been demonstrated and shown
to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit
(MMIC) three-stage power amplifier is integrated with two LTSAs. The LTSA and the MM'IC power amplifier has a gain
of 11 dB and power added efficiency of 14 percent respectively. The design is suitable for constructing a large array using
monolithic integration techniques.
14. ,SUBJECT TERMS
Amplifiers; Active antenna; Linearly tapered slot antenna
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OF REPORT
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19. SECURITY CLASSIFICATION
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Space Power Amplification with Active Linearly Tapered Slot Antenna Array

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