Antenna's elevation beam

Hi,

I have referred your question to our systems team

Will get back to you on Monday

thank you
Cesar

Hi Cesar,
do you have answer for me?
Thanks

Hello,
Typically there is a System Engineering requirement to have an azimuth field of view, elevation field of view, and a coverage area - bore sight max range. Other system parameters are also needed for the amount of antenna gain, coupled with the Tx signal strength, operating mode, single Tx, MIMO Tx, BPM Tx, or Cascade. Eventually we have an RCS target that is detectable at a range. The Sensing Estimator can be used, along with the software SNR needed for detection to determine at the top right, the max range of an RCS detectable object.

There are sensitivity tradeoffs for max range, range resolution, velocity max, velocity resolution.

Now for the antenna part, once you have your system engineering parameters, and the EVM mmwave Antenna simulated value, we can determine what your need is.

a) the passive antenna, like the EVM can have a different structure, as you have indicated, more vertical patch elements can results in a higher directivity, and peak gain. The number of transmitters are 3 for 1443, 2 for 1642. In the single Tx, the physical antenna layout can provide for multiple azimuth (2-1642), and multiple azimuth and elevation (3-1443). The number of receivers is 4 for each device.

In the existing EVM antenna there are 4 columns of Rx antennas of 3 patch elements. If you wanted to re-assign 2 Rx azimuth antennas, as an L like shape of 2 Rx azimuth, and 2 Rx elevation antennas, with 2 or 3 Tx, using the MIMO (one Tx at a time),
in the 1443 case, you could have 3x2 = 6 azimuth, and 6 elevation antennas, In the 1642 case it would be 2x2 - 4 azimuth and 4 elevation. If you have more critical azimuth requirements, you would have an EVM like 1443 antenna for Tx MIMO to have 8 azimuth receive antennas (2Tx-4Rx), 4 elevation antennas (1Tx-4Rx). The 1642 does not have an elevation MIMO Tx output, so the Rx L shape, or a different antenna architecture is needed.

Reference 3 discusses the RF feed topology for a stack of 4 patch elements. In the TI antenna design, the antenna elements are fed in series, in this reference there are power dividers to provide for parallel feed.

When we have specialized beam forming to increase directivity, there are phase delays to specific elements in this manner the antenna field of view is reduced, and the peak directivity is increased. Using a single mmwave sensor this is done with delay lines, power dividers, RF simulation to feed different phases of the antenna signal to the transmitter set, or receiver set or both.

Note: there are slot, coupled, dielectric lens, and horns that can be used as alternate antennas, refocusing the mmwave transmitter and receiver.

If the antenna directivity, and antenna gain profile results in a lower gain, you could raise the Rx LNA gain in the receiver.
This requires a system simulation, with an antenna different from the EVM. The projected scene in angle has to be determined. The Radar Chirp design, needs to illuminate the desired target RCS to get a return signal SNR db above the expected clutter.

Note: the antenna directivity and angle bias is also a function of the mmave frequency.
The spacing of the receivers is lambda/2, the spacing of the transmitters is 2*lambda.
The change is angle across the chirp range does change the antenna profile, so it needs to be
simulated at multiple static frequencies.

Note: the EVM Rx array rows have GNDed rows outside of the 4 Rx antennas.
This is in effect amplitude shaping. You could experiment with amplitude shaping
after the DFE output. You can only adjust the Rx Phase shaping after the Downconversion, it is normally
done in the length of Rx traces, as a phase adjustment.

In the attached EVM antenna simulations, the directivity gain for azimuth and elevation are shown.
You need to set values for Tx and Rx.

There are third party mmwave sensor module providers on the TI website, you could investigate
their antenna implementation as well.

References
1 - "orbanmicrowave.com/.../Orban-Patch-Antennas-2009-rev.pdf"
2 - en.wikipedia.org/.../Patch_antenna
3 - nopr.niscair.res.in/.../IJRSP 34(2) 125-130.pdf
4 - anteny.jeziorski.info/.../2011_Alsager.pdf

Regards,
Joe Quintal