We have in our building an RF signal receiver that opens the building entrance gate, something like this.

ours is like this one but have a socket for external antenna

Ours have a socket to use an external antenna, you can see it bellow. I live in the 4th floor and the signal is not received by the receiver. I have to go two floors down to get the door open :( so I want to use an external antenna I have, in order to try improving the receiver coverage by bypassing the original screw in antenna it has, which is buried under the stairs at the 1st floor.

this is the one used on our building

I have a 50 Ohm Impedance antenna with a male SMA connector (you can see it below). For what I have found, the receiver screw in antenna is also 50 Ohm. How should I connect the antenna to that PCB socket?

I have a SMA PCB socket somewhere and I thought of soldering the legs to small run cables and connect those cables to the PCB socket (center pin to antenna, other four legs to ground) or I could just strip the cable and connect the center pin in the antenna socket and the stripped outer jacket in the ground socket?

50 Ohm antenna with SMA male plug

  • \$\begingroup\$ Can you tilt the antennas so they are parallel to each other? An antenna illustrated in the first picture usually has bad sensitivity toward the axis of the antenna. \$\endgroup\$
    – Ralph
    Dec 19, 2022 at 18:23
  • \$\begingroup\$ Hey! You mean the receiver antenna? Nope, I can't. The transmitter is a handheld remote, like those cheap fobs for gate openers from china \$\endgroup\$
    – Cai
    Dec 19, 2022 at 18:29
  • 1
    \$\begingroup\$ Has the owner of the building approved your messing around with their building security equipment .... ? \$\endgroup\$
    – brhans
    Dec 19, 2022 at 19:22
  • \$\begingroup\$ I own one of the apartments 😌. Before doing anything I consulted the other proprietors if that whats worry you. This a problem not just for me but for my other neighbors too \$\endgroup\$
    – Cai
    Dec 19, 2022 at 19:55

1 Answer 1


or I could just strip the cable and connect the center pin in the antenna socket and the stripped outer jacket in the ground socket?

That one should work just fine.

Another option, if you can make it work, would be to find a short pigtail of flexible coax which has a longish SMA-female connector on one end. You would remove the old antenna screw receptacle, strip the pigtail and connect it to the ANT/GND terminals, and then secure (somehow — nut/washer or maybe even hot glue) the SMA-F to the hole in the enclosure where the antenna went. That way you don't have to cut the connector off of your antenna, and you can unplug or replace the antenna as needed.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.