Reach m2 antenna mounting

hello good day everyone!

i would like to ask if I use the reach m2 (as rover ) on a fixed wing UAV can I mount the antenna under the fiberglass skin of my UAV or it should be mounted externally(out side skin) ?

i am using a fixed wing uav with reach m2 module with Multi-band GNSS antenna

Hi Zeke,

Welcome to our community!

I’d recommend providing the Reach M2 GNSS antenna with a clear sky view 30 degrees above the horizon. GNSS signals are weak enough, so we can hardly predict if the antenna will get them fine even under radio transparent materials.

Please note that RF noise from electronics such as motors may affect the antenna’s performance badly. That’s why the antenna should be placed as far as possible from parts of the UAV that produce RF noise.

To check other recommendations on placing the Reach M2 antenna, you may explore this guide from our docs.

thank you for your response. that being said since the UAV is traveling at high speed, will not installing a ground plane be advisable? or can the ground plane be fix curved ? will this setup be advisable (pictured attached)?

The official stance is outside, but I have mounted it underneath a plastic tractor canopy without issues.

I would try with the plane on the ground, put it underneath the skin, get a fix, then start operating all the motors as if you where flying but do not take off. Then you would see if it breaks fix or has a noisy output. Also try it at simulated hard bank angles, to see when it breaks fix.

Outside no doubt is better signal, but inside is aerodynamic advantage. Science has two “E”'s because it takes effort and experimentation to learn new things.

Also you can use a flatter style antenna, the tallysman is extremely good, compact and light but it is one of very many choices.

thank you for your response, would you recommend TW7872 double band or TW7972 triple-band antennas for the emlid M2 ? since if I have to mount it outside this tallyman antennas has very small aerodynamic drag compared to the helical antennas

TW7872 = frequencies of :L1/L2/G1/G2/E1/B1
TW7972 = frequencies of : L1/L2/L5/G1/G2/G3/B1/B2/E1/E5a+b

The existing antenna Is a HC871 dual band, so i think the closest apples to apples would be TW7872.

Tallysman makes exceptional antennas, I have also tried Betian antennas from Aliexpress with success.

thank you , well noted. additionally i would like to ask if it is okay to mount the RTK antenna side by side with another gps module (m8p) . since this will used as a backup stand alone system for pixhawk

This I do not know for sure. They are both receivers so you think they would not be emitting anything interference wise.

But one shading and blocking the signal from the other is a real possibility depending on antenna height differences and location.

None of the Antennas see out the bottom, so if you fly upside down you will have issues, lol. This brings up a neat question if fighter jets have a gps antenna on both the top and bottom, never thought about that until now.

excatly, that is what I think as well. what if it is directly sided by side like perhaps 50mm distance between them, the height of the antennas will be the same. TW7872 antenna, here 3 GPS ( what would you think? @kseniia.koliuk @PotatoFarmer . by logic i can assume they do not cause any interference but what is your opinion

Hi Zeke,

If antennas or GNSS receivers are located close to each other, it shouldn’t influence their performance. Please note that if you plan to locate the receivers inside the UAV, you will likely need to provide them with additional ventilation.

Reach M2 receives the GPS/QZSS L1C/A, L2C, GLONASS L1OF, L2OF, BeiDou B1I, B2I, and Galileo E1-B/C, E5b signals. If you use an antenna that gets fewer signals, it may affect the receiver’s performance badly. If the antenna tracks more signals than Reach M2, the receiver will track all signals supported by its chip.

Reach M2 can be integrated with antennas that meet these requirements:

  • Antenna output current no more than 100 mA

  • Antenna DC bias no more than 3.3 V


thank you for your answer, well understood. so is TW7872 antenna suitable for the reach m2 ? or can you recommend another compact (small footprint) antennas by tallysman ? the TW7872 as i mention before receives GPS L1/L2, GLONASS G1/G2, Galileo E1, BeiDou B1 signals. looking at it i think it should be a perfect fit, but again please do confirm. thank you very much

Hi Zeke,

If the antenna meets the antenna output current and DC bias requirements, it should be possible to integrate it with the receiver. For connection to Reach M2, you can use a standard MCX connector.

As far as I see, Reach M2 can track more GNSS signals than the TW7872 antenna. In most cases, the receiver should get Fix fine with only L1/L2, G1/G2, E1, and B1. However, I can hardly predict if the lack of some signals will influence the receiver’s performance without local tests.


thank you for your response, well noted. then TW7882 will be a much better fit, would it? Coverage of

GPS L1/L2, GLONASS G1/G2/G3, Galileo E1/E5b, BeiDou B1/B2

or what compact antenna (not helical) would you recommend instead?

thank you very much

Just buy one and try it.

As long as the voltage and amperage specs match it should work. I have tried many dual band Ali express clone antennas and they have all worked great. Getting an actual tallysman should work even better.

will do , thank you

Hi Zeke,

As I see, the list of GNSS signals for the TW7882 antenna includes all signals tracked by Reach M2. So, if the antenna meets the specifications, Reach M2 should work fine with it.