V. I. Lapshin1, G. V. Zelepukina2, I. V. Trusilova3

1–3  JSC “V. Tikhomirov Scientific Research Institute of Instrument Design” (Zhukovsky, Russia)

In the developed by JSC “V. Tikhomirov Scientific Research Institute of Instrument Design” airborne X-band AESA the line-column structure of the microwave power distributing is formed from multichannel transmit–receive modules (TRM).

Up until recently the unsymmetrical strip power distributors were used as power distributors for transmission and reception in AESA. They allow connecting the inputs and outputs of the distributors with other TRM nodes using soldering with jumpers. It provided reliable contact for conducting transmission lines, but greatly limited the TRM maintainability and significantly increased the labor intensity of assembly and installation.

A fundamentally different approach is to use distribution systems based on a symmetrical strip line or a strip line with height offset. Strip power distributors, based on such lines, can be manufactured using the printed-circuit technique with built-in resistors, with outputs for the demountable microwave clip connectors. Possible disadvantages and advantages of both versions of the strip power distributor have been analyzed. Calculated and experimental data have been obtained for each version.

So this analyze showed the possibility of performing multichannel strip power distributors for TRM of the X-band AESA based on either unsymmetrical and symmetric lines or strip lines with height offset. In this case both versions provide the possibility for realization of the parallel power distribution schemes and the possibility of ensuring the AESA operating mode with two independent beams. At the same time the strip power distributors on the symmetric line can be used only in the hermetic package or with the air dehydrating system. The usage of these devices in electro-hermetic packages can lead to the parasitic resonances, for that reason it requires the installation of absorbing elements to eliminate them. In addition it is impossible to install external elements in close proximity to the strip lines.

There are not these disadvantages in the strip power distributors on symmetric lines or on strip lines with height offset, because microwave wave propagates in the shielded environment. But in this version it is impossible to make specific coordination of the turning that requires a fine-tuning of the topology on the design phase of the boards.

The undoubted advantage of this fabrication method is possibility to use bolted microwave connections on clip contacts to engage them with 50 Ohm outputs of other TRM nodes. It greatly reduces the labor intensity of manufacturing and repairing of TRM, in view of a significant reduction of microwelding and soldering process. When we use clip contacts, it is necessary to apply the boards based on stiffer materials with increased values of tgδ, that leads to a decrease in the efficiency of power distributors. But in this version the partial decrease of the amplitude distribution to the antenna edges should not reduce the AESA gain.

Lapshin V.I., Zelepukina G.V., Trusilova I.V. Application of microwave power strip distributors for AESA transmit-receive modules. Antennas. 2021. № 5. P. 65–72. DOI: https://doi.org/10.18127/j03209601-202105-07 (in Russian)

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