• Very nicely made, however I should point out a few things for it to work better. Firstly your S-band patch is linearly polarised so you will lose 3 dB. Not necessarily a problem with that amplifier. Secondly the "phase centre" of your two feeds look to be a long way apart - that is unless the 10GHz horn is acting as a director at 2.4 GHz but I don't think it is the right size for that. This means you can have one or other feed at the dish focus, but not both. Ideally you would want both at the focus, but if that is not possible, then make sure it is the 10 GHz one.

    Meanwhile, last year I designed another feed that is circularly polarised on 2.4 GHz and has the 10 GHz phase centre much closer to the 2.4 GHz phase centre.


    There are a few Twitter posts from me on it and some other designs for different pipe sizes, different patch shapes and with additional directors e.g https://twitter.com/TheRealMike/status/1077166330195951616


    I have updated the dimensions since then and we have iterated with various builders. The latest version is here.





    Here is the pattern at 2.4 GHz. Simulated but seems about right from the test units.



    What is not obvious from the drawing is that the 10GHz feed is replaced by the dielectric lens from a rocket style LNB. This allows it to match the dish but also does not interfere with the 2.4 GHz pattern. The third image below shows that feed on a test patch very similar to the one you have built. I also did a design with a small horn but the size of that horn has to be limited - see twitter.


    ...and it will be written up, eventually.



    73 Mike G0MJW



  • What you said is right.The focus of the 2.4 G and 10 G is a contradiction.But white guided wave tube can improve 10 g about 5-7 db.

    The length of the intermediate pipe because it is the return loss of 2.4 G.


  • 如果导波管延伸到5.5厘米以上,到2.4克回损几乎没有图像。如果导波管非常短。2.4克回波损耗只有- 20分贝。

    If guided wave tube extended to more than 5.5 cm, to 2.4 g return loss almost no images.If guided wave tube is very short.2.4 g return loss only - 20 db.

  • I don't really care about return loss as long as it is good enough. It is not an indicator of good antenna performance. A dummy load has an excellent return loss. The circular polarisation relies on two resonances and the bandwidth and hence broadband return loss suffers, but it is still over 20 dB in the band of interest.

  • What you said is right.The focus of the 2.4 G and 10 G is a contradiction.But white guided wave tube can improve 10 g about 5-7 db.

    The length of the intermediate pipe because it is the return loss of 2.4 G.


    Hence the plastic "Rocket" feed. This is the equivalent of the horn but has far less impact on the S-band.[Blocked Image: https://images-na.ssl-images-amazon.com/images/I/31g9hIxu7BL._SY450_.jpg]


  • On the first day of the Chinese New Year, I tested the LNB with 2.4g feed added. There seems to be no problem except for the -3db attenuation... If there is no bellows section, it will bring -6db attenuation. Did not test the 2.4g return loss, just recorded the most stable position...



  • Hello,

    I am very curious how the 2,4G patch feed performs in this construction (e.g. return loss, circular polarisation). The sreews of the LNB-mounting are very close to the patch feed and could make serious interference....but you will let us know ;-)


    73 de Johannes, DL5RDI - JN58xx

  • In order to solve the focus problem.I changed the connection part of the 2.4 G.3 d printing a conversion in diameter.

    I also made a small bell mouth guided wave tube.

    Made some different guided wave length of the tube.


    This is a book of vibration 10750 LNB, to do with the local oscillator leakage signal source.

    Take the LNB spectrometer can view just to 1 g signal (lo: 9750).


    Conclusion:

    Compared with no guided wave focusing device.LNB bellows can bring 5-6 db gain.Small bell can bring 2-3 db gain.

    So I decided to use only bell focusing.Es' hail - 2 signal strong enough.





    And return loss of the small bell mouth to 2.4 G feed without any image.This is the most important.

    Maybe this weekend I can put it on the butterfly antenna test.Hope everything goes well