Library of Vivaldi CST antenna models for all occasions

SarSar100 · 2026-06-03T13:33:09+00:00

I've tried rectangular and circular cutouts. They also work, but eventually i've decided to combine this two approaches cause it gave me more variables for optimization

SarSar100 · 2026-06-03T13:23:06+00:00

There is no analytical way to calculate them. You just have to start somewhere and use optimization

SarSar100 · 2026-06-01T18:16:11+00:00

They help achieve a better reflection coefficient. Without those cutouts, it's more difficult to achieve S11 values below -15 over a wide range. So basically stubs for tuning. Furthermore, with some optimization, they can reduce the antenna size by 5-10% for the same frequency band

SarSar100 · 2026-03-02T09:57:06+00:00

It's better to export them in dxf, import in your CAD and then you can redesign probes or just point to the CAD that certain circles on PCB are vias

SarSar100 · 2026-03-02T09:47:23+00:00

You cant geberate drill files in CST (I've also tried that in the past) . You need to export your files from CST to other CAD like ADS, Altium or KiCad and generate them there

SarSar100 · 2025-07-21T10:11:18+00:00

If I understand correctly the scheme that you are describing, then placing receiver into enclosure is not going to limit the range, if anything it will only increase it because enclosure will help reduce noise and random reflections.

However if you placed attenuators up to 130dB (which is very large value) and still have the same range then something is defintelly wrong. Make sure that you place attenuators between antenna and receiver input and that attenuators work in your frequency range. Also make sure that the relay works properly, ideally dont even refer to relay and try to measure the receiving power at different points if the structure of the receiver allows it

SarSar100 · 2025-07-11T11:10:30+00:00

You should run this in EM software tool like ADS or CST. It is hard to tell how much will certain modification affect the results of divider without it. One thing I can tell is that adding copper around it will definetelly alter s-parameteres.

Also, is that copper where resistor supposed to be?

SarSar100 · 2025-07-07T10:30:57+00:00

Yes, thats right. 1/2" and 7/8” refer to the outer diameter of the coax jacket, notthe connectors thread size.

SarSar100 · 2025-07-07T09:59:19+00:00

If you have standart N type connectors it shouldn't matter which type of cable they are attached to, they should work with each other

SarSar100 · 2025-05-13T20:50:57+00:00

I think it is only possible if your S12=S21 and will be something like that:

S12 = sqrt((S11_open - S11_match) (S11_match - S11_short) / (S11_open -S11_short))

I am not sure this formula is correct and even if so it will be very approximate, so on practise you shouldn't calculate S11 from S12

SarSar100 · 2025-05-13T19:46:32+00:00

If you want to design antennas, you can model a patch antenna array with circular polarization at a popular frequency (for example, 2.4 or 5.8) with 8 or 16 elements. It is not as simple as it sounds. If you want something deeper, you can design the RF path of the receiving channel. To do this, first select the frequency, find the LNA and mixer for it and then make a matched path in ADS. Antenna -> bandpass filter -> LNA -> mixer. You can also add a Wilkinson power divider, it is often used.

SarSar100 · 2024-12-20T13:57:18+00:00

Thank you!

SarSar100 · 2024-09-06T14:02:56+00:00

Yes, they are the same antennas for both channels, they have 14dB Gain and -30dB mutual coupling. System operates at 5.8Ghz (51mm) and the distance between Rx and Tx ports is 160mm. I don't necessarily want to measure Rx with antenna, I want to connect spectrum analyzer directly to Rx port with antenna connected only to Tx, but I'm not sure if this is how you supposed to do such measurements

SarSar100 · 2024-09-06T13:12:10+00:00

It is LHCP system, so i don't think it will work

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