A coaxial connector is used to feed a cavity resonator (ideal position at cavity center).
S11 is almst approaches to zero, which is completely wrong. Should I try to find suitable position across the surface of cavity for feeding point?
Please , remind me about ( S11 ) parameter , isn't expresses the matching / mismatching of the coupling of matching load with the transmission line ? Judging by the chart , you can only complain: at what frequency S11 vanishes and will be equal zero , and this is the ideal for you if the measured frequency = the required frequency ! wishing for you all the best in your research dear Bilawal !
Please , remind me about (S11) parameter , isn't expresses the matching / mismatching of the coupling of the matching load with the transmission line ? Judging by the chart , you can only be happy , and the only at which frequency it happened ? it must be when the measured frequency = required frequency ! wishing all the best for you in your research !
If your model is correct, then conduct a parametric study by moving the position of the feed, monitor field inside the cavity, your inner conductor should be parallel to the electric field.. I suggest that you look at the field within your coaxial cable. Good luck.
S11 represents reflection coefficient and its dB value approaches zero tells that almost whole power fed is flowing back towards feed. The characteristic is between 6 and 12 GHz tells that it does not match in this band, in other words it may match somewhere else. You can find out (by sweeping) and thus can determine at what frequency the cavity resonates or else if you wish it to resonate between the band, relook cavity design or feed position/orientation
Dear Bilawal,
your S11 plot shows that there are 3 resonant modes in the frequency band from 6 GHz to 12 GHz inside your cavity resonator. In order to tune and match your feed to the resonator, you should move one of these resonant modes to your work frequency. That means, one of the S11 minima should hit the working frequency, or in other words at work frequency the reflections should at least be below -10 dB (below -20 dB would be realy OK). You can achive this, by moving the feeding port, or by optimizing the geometry of your adapter (coaxial connector) using a 3D EM field simulator software. You should also know in which resonant mode will you work. Wish you good luck.
Hi!
Now the connector is coupled with the resonator very weak. Whether You need a big coupling? Lengthen the Central wire.
I wish you success.
Hello sir,
S11 is reflection co eff..means how much amount of power is coming back to source from load...so it should be negative as small as..below -10 dB sir,
I suggest change the feed pt..it is not necessary that it will always on center..any way on your antenna.
Regards,
Hi!
- 10 dB means 1/10 of the power. Your second and third pictures are not clear. Therefore, it is unclear what kind of design are we talking about and what your goals are.
Regards.
Thanks Zinal and Яков.
I found some mistakes in that design and when improved, S11 results were good. But unfortunately significant shift in resonant frequency could not achieve and that idea has to stopped.
Dear Sir
I think first of all , you need to check your design itself. Well, I am not against conducting parametric studies of the feed position and even as well as other design parameters. However, you design may not work at this specific frequency. So, try to play and check the whole design structure against different frequency ranges to come up with what you are aiming.
Rgds,
Hi!
The resonant frequency is shifted because of the strong coupling between the resonator and transmission lines. If you want to get the unbiased frequency, decrease the coupling. Please explain your drawings and goal.
Regards.
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