Dual Band Feed

  • Hello guys,

    Following the success of the Dualband feed designed by m0eyt, pa3fym and g0mjw, I decided to make one. With little more effort it was possible to fabricate all the parts for this antenna in larger quantities to support other builders. The parts are CNC fabricated to close tolerances. Are you interested? Please contact me www.hybridpretender.nl

    73 Hans pe1ckk

  • If anyone is interested, I have been adapting the antenna in two ways, firstly to add a "pie tin" choke ring as suggested by Willi HB9PZK to improve the radiation pattern and secondly a 2.2/8.4 GHz version that might be useful for detecting deep space satellites. This is a rather specialist application, trying to see if you can detect a satellite 100s of millions of km away. Easy with a 35m or 70m dish, not so easy from your back garden.

    The choke ring mainly makes a difference to the 2.4 GHz sidelobes. This is not significant enough benefit for QO100. It won't make the signals into the transponder much stronger; it would reduce interference to adjacent satellites, but there are none; it will improve the performance on 2.4 GHz receive, but QO100 systems do not receive on 2.4 GHz. Conversely, the 2.2/8.4GHz feed is only for receive so it's worth adding this.

    The Twitter thread is here https://twitter.com/TheRealMike/status/1177286413685014528

  • You say the "pie tin" reduces side lobes at 2.4GHz would this mean reduced transmit outside the dish area, I am sandwiched on 3 sides by other houses rather close by, so the less 2.4GHz I throw towards the other houses the better. I am thinking forward to when I try DATV at higher power. I know I am just being cautious. What height is the ring and does it go on the outside of 105mm ie can it be fitted to an already made POTY.

  • OK Mike I will leave as it is. I am not wanting to mess with a good antenna and I reckon I am doing well with 0.75 Watts to a 1 metre dish on NB. So it will be a case of do not touch.

    I am sure mk2, mk3 etc feeds will follow eventually, if so I will make one at the time, all that information not a lot to me i will have to understand smith charts first.:)