Abstract-The purpose of this paper is to present a complete design and analysis of a new integrated balanced transmitter operated at 4 GHz using microstrip technology. It comprises a 4 GHz two-port negative resistance oscillator and a microstrip-patch antenna resonated at 4 GHz. Three different modules are designed and analyzed. The first one used a Lange coupler as a power splitter while the second and third used a one (two)-section branch coupler. The components of the three modules are designed using full-scale computer simulation program named with MSDES, performed by the author, which fully takes into account all the discontinuities included in the microstrip lines, while the modules are analyzed and optimized using APLAC V7.61 software. The design methodologies of the two-port negative resistance oscillator and microstrip patch antenna are introduced and explained. The analyses of the designed modules show a better efficiency and good performance. The modules give a transmit-antenna gain of 15.7 dB with antenna beam widths 91.7 • and 18.2 • in Eand H-planes, respectively. The complete schematic diagrams of the transmitter modules are drawn. These modules can be used in satellite communications, Doppler and other radars, active and semi-active seekers, radio altimeters, missile technology, weapon fuzing, manpack equipments, remote sensing, feed elements in complex antennas, satellite navigation receivers, and biomedical radiators.

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This paper presents a detailed study of ptype Ga As IMPATT diode. This is important in order to get better insight into the operation of this type, which is not sufficiently studied. Hence it will be possible to design and optimize the structure of double-drift Ga As IMPATT and the circuit where this IMPATT is embedded. Some important conclusions concerning the effect of the peak value of the microwave signal on the IMPATT operation are drawn.

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In this paper, a complete program called HHSS2 is introduced which is a user-oriented program capable of designing linear active and passive microstrip circuits such as amplifiers, oscillators, mixers, lowpass filters, and couplers. The substrate parameters and the characteristic impedance of the microstrip lines are given to the program as a common statement. Examples for the design of a 3-GHz high gain amplifier, 2.6-GHz oscillator, ring coupler operated at 3.33 GHz, Lange coupler operated at 3.3 GHz, and maximally-flat lowpass filter operated at 2 GHz with 0.75 GHz cutoff frequency are introduced.    Key Words: Computational Microstrip Circuit Design, Microwave Circuits, Computer Aided Design.