A Microwave Engineering Journey

                                     
   1952-1996        1996-1998        1998-2000        2003        2004        2005

MICROWAVE JOURNEY

Radar Era (1952-1961)
Missile Era (1961-1971)
Phased Array Era (1971-1980)
Early MMICs (1980-1990)
MMICs Today (1990-2004)

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The Third Ten Years of the Microwave Engineering Journey
The Phased Array/Microstrip Era (1971-1980)




In 1972 Texas Instruments was executing the development of an Airborne Electronically Steerable Phased Array (AESPA) program for NASA Huntsville. When all the program members abandoned the program and left Texas Instruments, I became the program manager. This research program goal was to develop a prototype 48 element S-Band steerable phased array antenna.On the left is shown the assembled array from the back side to reveal the modules. Also shown is the interior of a complete module assembly.The Two project team members shown are technician Jack Lassiter and project engineer Robert Coats. Work on the program included: (1)Assembly and test of the T/R modules, (2) design and fabrication of four receive manifolds, (3) design and fabrication of four transmit manifolds, (4) design and fabrication of four DC/Logic manifolds, (5) assembly and test of the complete array, (6) and demonstration to the customer.
As indicated in the title, most of the circuits in this period were realized using microstrip transmission line. This configuration is a single dilectric layer with one ground plane and planar conductors on the top side. The dielectric commonly used is Aluminum Oxide (Alumina). For the AESPA program Stripline was used for the manifolds and microstrip was used for module circuitry.



This was the first Phase Shifter design that I worked on at Texas Instruments. The work was done in the year 1972. It was a three bit Octave Band unit designed to operate in the 2.5-5.0 GHz frequency band. It was a microstrip configuration employing 0.020 inch thick Aluminum Oxide substrate and PIN Diode switches. It was done at the time Texas Instruments first began to make use of computer aided design tools. Designs were performed by inputing data to an IBM 360 computer using punched cards. The CAIN01 software was developed by TI. Later software developments include COMPACT, TOUCHSTONE, ADS(HP), and MICROWAVE OFFICE (AWR). Work was performed at the Antenna Lab in Renner. Leaders included Charles Fincher and Glen Gaustad. I authored a technical paper on the work that was published on pp. 444-449 of volume MTT-21, Number 7, July, 1973.


In 1973 I worked in the Antenna Lab for Allen Jones on an S Band SATCOM Module Development Program for the Naval Research Laboratory. I designed a five stage power amplifier that provided 7.1 watts CW output at 2.7 GHz with a gain of 32 dB and efficiency of 31.2 %. The two stage pre-amplifier used HP 35820A transistors and the post amplifier used MSC type 3000, 4001, and 4005 grounded base transistors. The interstage networks were microstrip in form, and utilized .020 inch thick alumina substrates. The transistors were load pulled using two HP slab tramsmission-line probes. I was promoted to job grade 30 (Senior Engineer) for my work on this program.


In 1976 I joined a team developing a Tactical MLS System for the Army. The program manager was Jim Nix. The three bit C Band phase shifter was a reflection type constructed on three layer strip-line transmission line using Duriod dielectric material. The figure on the left is the assembled RF circuit. The figure in the center shows the form of the PIN diode assembly. The figure on the right shows the completed assembly that includes the driver circuitry.

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