I've made an interesting remote using an Arduino and a nRF24 module with the antenna however it seems to be performing rather poorly compared to a usual nRF24 remote, I have a couple of hypotheses as to why and I would like to know if anyone can confirm or refute them.
As a preamble I've been able to achieve at least 170 m of range with this module, however the receiving module was also one with the external antenna and it had line of sight, both of which were not the case with these tests, this time the receiving module is the small nRF24 with the PCB antenna and the signal has to go trough 3 brick walls, however it still seems to fall short because I was able to achieve about 1.5x range with both the transmitter and receiver being the small module
trough those same 3 brick walls where the range was about 20~25 meters wheras with this remote i was only able to get about 15-ish meters.
I am using a PA level of MAX on the transmitter and MIN on the receiver.
As you can see in the attached images the design of this remote relies on de-soldering the antenna from the nRF24 PCB and rotating it so the antenna goes over the PCB saving space, the first hypothesis is that this counterflow of current is causing the signal to weaken in particular directions.
from testing this seems highly unlikely because the remote seems to perform identically in all rotations.
The 5 pins connecting to the nRF24 PCB to the antenna all have distinct purposes that cannot be fulfilled due to the fact I didn't solder three of the pins on the antenna to the PCB as can be seen on the third picture, I've checked the pins and they all seem to be internally connected to each other and the four outer pins directly connect to the bronze body of the antenna which makes me skeptical of their purpose other than structural strength however if anyone knows of their exact purposes I would like to know.
My ghetto powering setup has wires that are too thin to reliably power the nRF24 module,
the power is delivered from 4 AAA batteries in series to the VIN pin on the Arduino and a 3.3V AMS1117 module that powers the nRF24 module there are 10 and 100 uF Cap's on the 6V and 3.3V lines respectively
I don't see a question in your question. generic antenna info for people in a region regulated by the FCC:
technically all part 15 devices must be certified with a particular antenna, which must be permanently attached, or connected by a non standard RF connector.
practically, if someone makes a non standard RF connector adapters will come on the market to connect the non standard connector to a common connector. manufacturers certify radio modules to work with the puny spring like antenna soldered to the board. this lets them set the transmit gain as high as they can get. you can technically add a gain antenna, but not legally.
the kind of antenna you are using has more than one name. It is a quarter wave dipole, AKA a Marconi dipole it requires a ground plane to operate effectively. an ideal ground plane for that antenna would be a 2.4"/ 61 mm diameter copper disk, soldered to those 4 outer pins, with the antenna sticking up at a right angle. a little bigger is better. the best angle for this antenna is vertical
the rules for antennas would baffle a Beverly Hills divorce lawyer.
antenna gain works both ways on both ends. that Marconi has a 2.14 dbi gain - dbi is deep geek stuff. the Marconi antenna is the simplest antenna possible, so if any antenna has more gain than 2.14, the actual improvement is claimed gain - 2.14. An 8 dbi gain antenna has 6 db gain over a quarter wave antenna. So, an 8 dbi gain antenna on either end gives both ends a 6 db gain through the system. an 8db antenna on both ends would give a 12 db gain overall.
people get cited for running excess power on Part 15 systems about as often as people die of stomach cramps from swimming too soon after eating.
