Toni Ivanov

Analysis and measurement of hard horn feeds for the excitation of quasi-optical amplifiers

Measurement and analysis of hard horn feeds for excitation of quasi-optical amplifiers has been performed. A computer program based on the mode matching technique has been developed in order to determine the aperture field distribution for pyramidal hard horns. This program can be used to optimize a hard horns field distribution and bandwidth. Simulation and measurement results for a 31 GHz hard horn feed are presented.

One- and two-stage spatial amplifiers

This paper reports the design of nine HEMT, one- and two-stage spatial amplifiers which employ a common ground plane for receiving and transmitting port isolation and for heat sinking. By placing the spatial amplifier array in the near-field of the transmitting and receiving horns, a net gain of 8 dB was obtained. This paper also reports the first demonstration of a two-stage spatial amplifier constructed by employing near-field coupling of two single stage spatial amplifiers in free space. >

Two stage double layer microstrip spatial amplifiers

Several two stage spatial amplifiers are presented. The amplifiers were constructed on double layer back to back microstrip circuits with a shared ground plane. The ground plane provides an effective isolation between the receiving antenna array and the transmitting antenna array. Furthermore, it serves as a heat sink in high-power amplifier design. The coupling between the two stages is accomplished through microstrip to slot transitions, therefore there is no electrical contact from one layer to another. This facilitates monolithic fabrication of such amplifiers. The measured gain of a 3/spl times/3 spatial amplifier at 9.95 GHz is 18.0 dB.<<ETX>>

A nine HEMT spatial amplifier

A spatial power combining amplifier using HEMTs is designed and fabricated. The amplifier has a maximum gain of 5.5 dB at a frequency of 10.9 GHz with a 3 dB bandwidth of 1 GHz. The circuit is implemented on a double layer microstrip structure for effective input and output isolation.<<ETX>>

A CPW fed microstrip patch quasi-optical amplifier array

A CPW fed microstrip patch quasi-optical power combining amplifier array is introduced. The amplifier array uses CPW fed patches for both input and output antennas. This structure is not only compatible with MMIC implementations but can also provide a greater bandwidth for the patch antennas. A 4/spl times/4 amplifier array was designed and fabricated at X-band. Theoretical and experimental results are presented.

A transmit-receive spatial amplifier array

A transmit-receive spatial power combining amplifier array is introduced. The amplifier unit cell utilizes one antenna for both transmit and receive modes. Orthogonal ports of a microstrip patch antenna provide isolation between transmitter and receiver ports. Results from a 3/spl times/3 transmit-receive amplifier array design at 10 GHz are presented. The measured gains for transmit and receive modes were 8.2 and 6.9 dB, respectively.

A passive double-layer microstrip array for the construction of millimeter-wave spatial power-combining amplifiers

A passive double-layer microstrip array for the construction of millimeter-wave quasioptical amplifiers has been demonstrated. A total insertion loss of 3.1 dB was measured for a 138 element divider/combiner at 35.1 GHz. The 3-dB bandwidth is larger than 1 GHz. The array incorporates microstrip-slot-microstrip transitions with an insertion loss of 0.2 dB at the design frequency and microstrip patch antennas with an estimated efficiency of approximately 72%.

An extended resonance spatial power combining oscillator

A new circuit topology is presented for a spatial power combining oscillator based on an extended resonance technique. This oscillator uses annular slot antennas as the radiating elements and is more compact than the extended resonance circuits previously reported. A nine device power combining oscillator has been designed, fabricated and tested at the operating frequency of 10.11 GHz. The radiation patterns in both E and H plane have been measured and compared with the theoretical patterns. An effective isotropic radiated power of 2.4 W has been obtained from the nine device combiner.

A double layer microstrip spatial amplifier with increased active device density

A new quasi-optical amplifier consisting of four HEMTs coupled to a single receiving and a single transmitting microstrip patch antenna is presented. This circuit can be used as a unit cell for the construction of a power combining amplifier array at millimeter-wave frequencies. The advantage of this circuit is its high active device density which is desirable in the construction of monolithic integrated circuits. The amplifier was constructed on double layer back to back microstrip circuits with a shared ground plane which provides an effective isolation between the receiving antenna and the transmitting antenna. The coupling between the two stages is accomplished through microstrip to slot transitions, which facilitates monolithic fabrication of such amplifiers. The measured gain at 10.1 GHz is 10 dB.

Quasi-optical microstrip amplifiers based on multilayer coupled structures

Single stage and double stage quasi-optical amplifiers are presented. The amplifiers are constructed on double layer back to back microstrip circuits with a shared ground plane. The ground plane provides an effective isolation between the receiving and the transmitting antenna arrays. Furthermore it serves as a heat sink in high power amplifier designs. The single stage quasi-optical amplifier had a gain of 7.54 dB at 10.04 GHz and the two stage quasi-optical amplifier had a gain of 18.0 dB at 9.95 GHz.