Simple dual band dish feed for Es'hail-2 / QO-100
Mike Willis G0MJW, Remco den Besten PA3FYM, Paul Marsh M0EYT February 2019
An easy to build 2.4 and 10 GHz dish feed, using commonly available materials, for Es'hail-2 / QO-100 deployment is presented. The feed consists of a LHCP patch antenna for 2.4GHz and a waveguide feed for 10 GHz, to be placed in the focal point of commonly available and cheap offset satellite TV dishes with f/D's of around 0.6.
The 2.4 - 10 GHz dual band feed was designed and modelled with CST Studio (student edition) and comprises of a LHCP patch feed with a circular waveguide passing through it. Because the (free) student version of CST Suite has limitations there initially was some concern if the modelled results could be realised in practice. Modelling and optimising the patch feed meant adjusting the patch size, patch spacing, cut-out size and feed point location. All variables were iterated towards the final dimensions to let the patch generate LHCP and a sufficient match to Z = 50Ω resistive at 2400MHz.
Work in Progress - Before picking over this page, please go and look at http://www.pabr.org/radio/lnblineup/lnblineup.en.html which is a comprehensive resource on this topic.
The following is a list of PLL LNB's for Ku band;
Need info + photos
PLL LO / Down converter IC is a TFF1014HN with a 25MHz XTAL.
This blog post explains how to get the USA-Satcom xHRPT decoder up and running. The decoder runs on Windows and needs a reasonably modern CPU as some of the FEC routines are fairly CPU intensive. In this post, the Airspy R2 or Airspy mini SDR will be used; both of them perform about the same for HRPT reception. It is assumed that you have a tracking antenna already and the appropriate L-Band feed / low noise amplifier etc.
A script was needed to get ephemeris data on a daily basis from JPL and to write the data out in individual files. In the good old days, one would visit https://ssd.jpl.nasa.gov/horizons.cgi and manually enter the required data to save out the file containing pointing data.
A short writeup on the steps taken to convert a Radarmec 409 tracking head into a precision dish pointing mechanism. As supplied the 409 has two rather large 60V motors, position feedback is via synchro resolvers. The unit was destined to use digital encoders and lower voltage motors. The existing 60V motors were tested at lower voltage but it was not possible to control them with enough accuracy to do justice to the digital encoders, to they had to be replaced.
Having worked my way up in frequency topping off at 32GHz for the NASA Kepler mission, I needed to refine my microwave construction skills once again and try to build a converter for higher frequencies. I had looked around at 38GHz microwave links but terrestrial stuff is very strong and therefore pretty easy to receive. I needed to find some signal from space around this frequency. Having a dig around on the Internet I found a Czech site detailing their commercial 39.4GHz AlphaSat receiver here. Looking at the antennas showed that with relatively small apertures reception would be possible. AlphaSat's primary mission is maritime communications in the L and Ka bands but it hosts a number of Technological Demonstration Payloads, the most interesting one is Payload 5; there is a summary write up on the ESA here