Short antennas for A7105 and NRF24L01

I fly mostly mini quads and helis in my living room so would the onboard short antennas or printed antennas for these modules be sufficient? I take them out in the yard once in a while but usually within 50m or so. I trying to avoid drilling holes in my transmitter. Better yet, any options to give me the best range with internal antennas? My A7105 has a really short 1 inch antenna soldered on it and my NRF24L01 has a printed antenna.

The most important thing affecting the range is whether or not you have a PA/LNA. The PCB antenna might change the range, but I'm not sure you can get one of those with a PA/LNA, so it may not matter. The long/short antenna doesn't change the range. The radiating part of the antenna in both cases is about 31mm (¼ wave) long. The rest of the wire doesn't radiate, and just gives you flexibility in positioning the antenna to avoid reflections, blockage, etc.

I have an NRF24L01 and an A7105 in my 6s, both with PCB antennas with no PA/LNA. No problems flying indoors, or in my small front yard out to maybe 50 feet.

You should be fine if you get the version with the PA/LNA and leave the antenna inside the case.

Okay so modules with no PA/LNA then the printed onboard antenna should be okay since it's limited any ways with no PA. I also ordered another NRF24L01 with a PA/LNA and it has a uFL connector with a simple wire antenna. Most videos on Youtube suggest putting an RP-SMA to the uFL and then using an external antenna. Inside or out, it won't give significant increase in range would it?

I understand PA is for "power amplifier". What is LNA meaning? "Low Noise ______"?

All ¼ wave dipoles will have the same range under the same conditions, and that's what the little wire antennas soldered directly to the board and the duck antennas bundled with most SMA kits are. One advantage of the external connector is that you can use a high-gain antenna, or something with a different radiation pattern than those.

The key phrase is "same conditions". Using the wire antenna in the Tx means the antenna and transmitter have a fixed orientation. The external antennas orientation can be changed. Piloting aircraft, I tend to point them along the flight line parallel to the ground, and then twist my body and the Tx to keep the line to the aircraft and the antenna perpendicular. Piloting surface vehicles, I point it straight up, since they aren't likely to be either overhead or underneath me. I do see an increase in the RSSI telemetry when the antenna is properly oriented. Nuts, I see a 10dB drop when I turn the craft so the Rx antenna is pointing at me! The other issue is that you don't have to worry about metal bits in the transmitter interfering with the signal, but you should be able to avoid that when you install the antenna.

LNA is "low noise amplifier". Typically used to amplify the received signal, which for su would be any telemetry signals, and some protocols have an acknowledgement packet.

thanks for the explaination. seems like I won't need to add an external if i'm just flying mini's within close range.

So the short little antenna wire that is soldered to the A7105 module. It looks like any 20awg wire. It's not the antenna type that has an outer shell or insulator... is that sufficient? It doesn't even look like it's grounded. Just the single wire connected, the ground pads on the module have no connection.

If the antenna is just a simple wire, with the correct length, then no ground is needed.

It's only when you want to move the antenna away from the board that you need to use a shielded cable where the shield is attached to the ground.

Okay gotcha. Thanks.

I don't want to open a new thread for this question I hope I can get answer here I am trying to find info on how to change the little antenna on the A7105 module.

If it is needed I don know really I will follow this but I didn't see anything regarding the antenna www.hacksmods.com/2013/04/walkera-devo-7...x-flysky-hubsan-mod/ but is not from the A7105 module I think it from some modules taken from other transmitter it seem I have the A7105 from banggood

thanks

Hi, you'd need one of these antennas. Cut off the metal uFL connector and then solder the center wire and shielding to the A7105 board. Or you buy one of those RP-SMA cables with uFL connector and then you can add an external antenna.

Couldn't you just lenghten the antenna wire to 1/2 or 3/4 wave to add range?

There is a very knowledgeable "antenna" guy over at RCgroups that I stumbled upon from google. Lots of really useful info in one little blog/thread here:

2.4 gHz magic number 31.25 mm
www.rcgroups.com/forums/showthread.php?t=2371720

I'm using RG405 coax cable, you could use other, but I like the bend then hold to shape properties of this thin diameter stuff. Personally a bit stymied with completion (unplanned/unexpected medical issues), but hoping to get back to it soon. Anyway, I learned alot in that thread, hope it helps...

Thanks guys but I already did it after seen AndyRC video of devo 7e, I didn't use any length, just cut one of this www.banggood.com/10cm-PCI-UFL-IPX-to-RPS...-Cable-p-924933.html and soldered to the module.

I would like to get better and shorter antennas I have two modules with this antennas and they are to long , 19cm , it is super annoying and uncomfortable[
www.banggood.com/Wholesale-Dual-Band-2_4...ntennas-p-49578.html
Any suggestion ?