Antennas on Soviet spacecraft

Sven Grahn

Interkosmos 16 platform

The small sun-pointing spacecraft developed by Yuzhnoye in Dneipropetrovsk has an interesting antenna design for what I think is the 180 MHz telemetry downlink. On the back of each solar panel, there is a mesh mounted on insulators a few centimeters away from the panel back. One edge of the mesh is grounded to the panel. A coax feed the mesh with RF power as shown below. The reason for using a mesh is that it is transparent to infrared radiation, a feature becessary to radaiate heat from the solar panel. This antenna resembles a patch antenna. It is a clever antenna. No rods needed, very simple manufacturing, takes up very little room!

Antennas on Interkosmos 16

Bruce Blevins, Telecommunications Team Leader at the Physical Science Laboratory of New Mexico State University has helped identify the antenna type as a "planar inverted-F antenna" described in the book "Analysis, Design, and Measurement of Small and Low-Profile Antennas", Hirasawa and Haneishi, Artech House, Boston, 1992." The figure below shows the resonance condition. So, the estimated operating frequency is relatively close to the observed signal at 180 MHz!

This kind of antenna can be examined at a full-scale model of the Interkosmos-1 satellite displayed at the National Museum of Science and Technology in Stockholm, Sweden. That is the source of the dimensions in the figure above.

Small Ukraine Kosmos platform

Similar in design to the Interkosmos 16 platform, but with a different antenna for its main telemetry link, there are several small satellites designed by Yuzhnoye. Instead of the "Planar Inverted-F Antenna" described above it has a little loop antenna with one side connected to chassis ground. The other end is fed via a coax through the outer panel of the satellite

180 MHz loop antenna

The length l has been measured at a model on display at the Museum of Technology in Stockholm in July 1978. l=0.8 m. If this is half a wavelnegth, then the wavelength is 1.6 m. This corresponds to 187.5 MHz. This agrees rather well with observations of PPM-AM telemetry near 180 MHz.

In addition to these antennas there are two more antenna systems on this kind of platform as shown in the figure below.

Antenna system on Yuzhnoie platform

The command reception antennas for 50-80 MHz in the figure above are made up of rolled-up pre-stressed stell bands that form a tube when released. They can also be examined on the Interkosmos-1 model at the National Museum of Science and Technology of Sweden mentioned above.

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