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tomasbj

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Posts posted by tomasbj

  5. Posted

    @Ukamurubasu, active S-parameters or F-parameters in CST are useful for phased arrays, or antenna systems in which one would like to quantify the coupling effect between both antennas. This is useful if and only if you use simulataneous excitation. Otherwise there is no sense to look at this active S-parameters. These are measured when the device under test (DUT), such as an antenna, is in an active state, i.e., it is powered and possibly transmitting. In this state, the antenna or network can exhibit different characteristics due to the influence of active elements like amplifiers or transistors. Active S-parameters are crucial for understanding the performance of the device under real-world operating conditions. They can provide insights into parameters like active input and output impedance, gain under active conditions, and the stability of the device when transmitting. This is very important in phased arrays, beamforming. The conventional S-parameters we use to work are called passive S-parameters. You get it!

    Added to this, calculate the reactive near field at the corresponding working frequency and check their separation distance on your satellite. So that if they are inside of the near field sphere, avoid it!. Because mutual coupling will be there.

  9. Posted

    On 5/12/2022 at 5:43 AM, Admin said:

    Eco, the box is very big and has no point, and the biquad antenna is connected like this...

    e86147fe319638d9a114387caa95650a.jpeg

    I see this antenna is connected to the reflector to the other side of the feeding. Why? and what is the difference between connecting it to ground or not at that end position. Thanks

  10. Posted

    On 3/5/2018 at 9:45 PM, Admin said:

    The cross antenna is a medium gain and circular polarization structure made of a conductor or a strip line over the ground plane following a cross contour of four or more branches.The construction repeatability is verry easy as well the facility to obtain 14dBi gain in a small antenna.

    cross 5,5_01-tile.jpg

    cross 5,5_07.jpg

     

    cross 5,5_01.gif

    Could you please explain how the wire ends in this design?

    Apart, I understand the wire lenght should be lambda/2. Am I right?

    Do you have a .cst file to check the design?

    Thanks in advance for your help.

  13. Posted

    On 10/9/2017 at 7:28 AM, Admin said:

    MrElec see this....

    the U-slot variant with truncated corners

    Untitled_0_01.gif

    Very interesting Could you please share realized gain vs frequency? S11 too? I see you are exciting two orthogonal modes and breaking simetry with truncated corners and U-slot. What is the benefit of this? increase the bandwidth? Improve the axial ratio?

  17. Posted

    Hello, thanks for your answer @Admin . Apart, to make this antenna work at those frequencies and have 2dBi gain... should this antenna have an amplifier and matching network? I made my own model and the gain is very low. Thanks in advance for your help.

     

     

  22. Posted

    No, you are right ;) haha

    I am interested on these type of antennas. In fact, I want to use this antenna solution to cover 30-170 MHz, with gain higher than -25 dBi. And consider a weight to be less than 1 Kg. A  very challenging antenna. But who knows... perhaps, including ferrite and some dielectric materials I can achieve it. Otherwise... I will try another technology. Thanks for your support and asking.

  25. Posted

    On 2/4/2023 at 9:21 AM, Admin said:

    ,,,this system is a bit complicated, but I think it can be executed...!!!
    ,,,and why the frequency of 300MHz...???

    ,,,model of a tunable antenna embodiment with Variable capacitors....!!!

     

    I don't understand your question when you said, why at 300 MHz. Do you mean why is this antenna working at 300 MHz? Physically talking.

    Or why am I interested on this frequency range?