433mhz reception issues

I am trying to improve 433mhz remote control reception.

I am using the RCSwitch library.
I am using arduino nano.
I am using a superheterodyne receiver.
I am using generic 433mhz remote control with 4 buttons

I notice a few things:

  1. the spring antennas (I tried 2 types) makes basically no difference to no antenna at all.
  2. Despite what I read on the forum, I ran receiver at both 3.3 and 5v and there is no range difference
  3. the 12v battery in the transmitter, as it gets weaker to 11 volts or less, the range decreases
  4. I can get signals of 30ft or more but not in all remote orientations, its possible to hold the remote at certain angles and it won't work even at 10-12 ft., but less than 10ft it always works.
  5. adding a 17cm wire antenna did not help, but adding a 17cm wire to both ground and antenna pin DOES help. I need both wires, and the signal definitely works about 50% further and more orientations. I can use a spring antenna on ground, or a bent wire on the ground, but the antenna wire needs to be straight 17cm to get the improvement. In either case it still does not reliably work in all orientations of the remote control especially around 20ft distance or more.

What can I do to improve reception? Should I try a different software or antenna. Any insight appreciated.

Do you have other hardware connected, for example a display?

The receivers run on 5V only. The transmitters can usually be run at 9 or 12V, but the 4 button remote might have restrictions. Post a link to it.

For really excellent performance, use a balanced dipole as shown below. One inner connection is to ANT, the other to GND. Total distance from tip to tip is 34 cm.

TX and RX antennas must be parallel for best range (300 m line of sight, or better).

You haven’t identified the actual hardware involved, I’m going to guess that they are poor performers.

Selecting high performance RF modules might increase your range. Good receiver sensitivity and
good transmitter power+efficiency are what you need for best range. Also being able to select
modulation bandwidth is useful as there is a trade-off between bandwidth and range for a fixed
output power.

Yes, you’ve discovered that a 1/4 wave antenna needs a ground plane, or needs a ground element
to make a 1/2 wave dipole - that’s expected. Any module with just a 1/4 wave wire antenna is
using the supply/data wiring as the ground element, which isn’t ideal, but will work if that wire is
long enough and opposite to the antenna wire (often the case if mounted on top of a pole).

Another possibility for poor range may be the environment - you’ve not stated if this is line-of-sight
comms or some other situation.

The RF region of 433.9++ is FULL of devices transmitting. Al devices must have short transmissions and limit the power and limit the times per second to transmit.

Reliability has to also be built into the protocol used to communicate. That includes error checking and re-transmission of the messages. Possible the easiest will be to number the messages sequentially and do something when one is missing. Each message could also be sent several times and the receiver ignore duplicates.