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I have multiple Yagi antennas horizontally polarized. They are all placed in closed proximity at the same height horizontally and operating in a similar frequency.

The yagis are 2.45GHz, bluetooth band, so they are quite small in size. There is an array of them (PCB antennas) mounted in a radial array of 180. The back of the antennas are very close together, like an 1" apart. The purpose of this design is to be able to gather where a signal is coming from. Is there a way to make them so directional or introducing an element, such as a metal panel that would prevent them from overlapping?

The back lobe from the antenna's is overlapping with the from lobe with other antennas. I'm wishing to be able to prevent that.

The only idea that does to mind but I don't know if it would work is to place a solid piece of metal, grounded, in between the antennas.

Will this work? Are there better ways of creating this antenna to antenna isolation?

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  • $\begingroup$ Tom, I added further details and explanation at the bottom $\endgroup$
    – PHOLAN
    May 21, 2021 at 1:48
  • $\begingroup$ Thanks. So if the goal is to find which direction a signal is coming from, there might be better antennas than a yagi. How did you decide on a yagi? Do you need lots of gain, too? What would the ideal pattern look like - a 45 degree wide beam of at least qst X dBi, and then the back and side lobes no more than Y dBi for the back 270 degrees? Do you get RSSI, like Bluetooth or WiFi, or just detection / no detection, like the NRF transceiver chips would give you? $\endgroup$
    – tomnexus
    May 21, 2021 at 3:07
  • $\begingroup$ Based on my limited knowledge, I thought the Yagi was the most compact and directional option. What do you think will be best? Ideally I want to be able to 3D print it as part of the final design. I need gain but only for the purpose of making it highly directional. The main premise is to know exactly where a transmitter is located (in the 0-180 degrees) and be able to communicate with it. My concept is to have multiple antenna's oriented in about 30 degrees from each other in the semi-circular pattern and measure the RSSI to determine the location of a remote beacon via BLE. $\endgroup$
    – PHOLAN
    May 21, 2021 at 13:53
  • $\begingroup$ Tom, I started doing some reading. Do you think a antenna might be better for this project? Are you interested in doing some consulting for me on this project? $\endgroup$
    – PHOLAN
    May 22, 2021 at 11:26

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You are using a high enough frequency to be considering patch antennas as a practical solution.

You may try to calculate the size with this site : https://www.pasternack.com/t-calculator-microstrip-ant.aspx With a standard 4.4 FR4 PCB it gives you a size of 38mm x 29mm. If you print yours on JLCPCB for example you may even be able to put two patches on a PCB to make an array. There standard size for PCB is 102mm x 102mm over that you pay a little more.

The more patch you will be putting for the same antenna the more gain and directivity.

Moreover for what I understood you are doing, having a lot of antenna for quick and cheap may be useful.

Theses antenna doesn't mind being put in close proximity with others, we are doing that in FPV without problems.

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  • $\begingroup$ Arnaud, Thanks for the feedback. I'm looking into the link you sent. How did you get to those dimensions? what should I enter as the dielectric constant and height? $\endgroup$
    – PHOLAN
    Jun 14, 2021 at 15:17
  • $\begingroup$ The dielectric constant for FR4 is around 4.3, the classic thickness for PCBs is 1.6mm $\endgroup$
    – Wireless Learning
    Jun 14, 2021 at 20:51

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