Reach Antenna & Ground Plane Choice

I have a question regarding antennas - Luke W recommends the TW2410.

I have tried using a TW3040 and a TW3400, based on some reading I did, and can unequivocally say that the stock antennas work better than these (ie, more “green” satellites…) - I think this is likely because the high gain of these “better” ones saturates the Reach gps. Basically I chose without understanding the subject matter properly:)

However I would like to use better antennas if they do indeed work better, as in places it is hard to get 5 solid green satellites even with decent view of the sky.

Q1: Does someone have a rough idea of how much better the TW2410 (for instance) will perform than the stock antennas?

Q2: In most applications I read online people are striving for the smallest ground plane possible. For me in a surveying application size isn’t an issue (within reason!). At present I have a 100mm circular aluminum GP, based on my research so far. Will I get benefit from increasing the size?

Q3: Does it matter if the GP is ferrous / nonferrous?

Q4: Does the GP need to be grounded to anything (ie, the ground!) or doesn’t that matter? (With through-hole antenna like the TW3040 the plane gets grounded to the ground of the GPS cable, but with stick-on ones like the stock antenna or the TW2410 there wouldn’t be a natural electrical connection.)



Allen from Tallysman recommends the 3710 and I believe Igor recommended the 3740. You can special order the antennas with any cable length you want and any connector. Special orders from Digikey don’t seem to cost much more but it will take more time to receive them. The 2410 does not give you Galileo satellites, which the Reach is supposed to support in the near future, I hope.


A2: I think, increasing the size might be better regarding multipath reception and the ‘gain’ might be higher, it might also change the resonance frequency of the antenna as also other enclosures on top might do. But only with proper measurement equipment one can optimise the set-up.
A3: ferrous and plane
A4: No

I special ordered the TW3710 and it should arrive very soon. I have been testing my Reach in an area with tall trees with the TW4721 that comes with the Reach kit. The TW4721 does not have enough sat coverage to get a fix. When the TW3710 antennas arrive, I will do a comparative test at the same point.
Allen with Tallysman recommeded this antenna and says that it will out preform the TW4721.
I will let you know when the comparative results are done.

1 Like

Would be interesting, if nearly doubling the outer size and more than threefolding the price shows better reception.
The patch size of the TW3710 seems to be a secret ( I like incomperable specs.). It has one LNA per feed, the TW4721 has only one LNA. Thats it, Ampl. gain and noise figure: no difference. Better sat coverage? How? So I better don’t say, what I think…::confused: but let’s wait…

Test will come next week when antennas arrive. Price is much lower that you are thinking. I ordered with 600 mm cables. Special ordered from Allen with Tallysman says it will make a difference. I will set it up at the same point and run an equal length test. I know the GNSS sats have better signal at different times so it is hard to compare apples with apples.

Is this the same antenna as at this link? This is listed as around $100. Can you list the custom part # you used?

The part number is: 33-3710-02-11-0610
Your link is the correct antenna, but I changed to a low profile so it would fit the bracket that is being 3D printed. I received the one you linked to in the picture and returned it for the part number above. Allen, specified it out for me at Tallysman.
The 0610 is a 610 mm cable coming out of the antenna with a connector for the Reach.
It does not show on my order as shipped because DigiKey had to make a special order for the antenna.

Ok, sorry, I just looked at the wrong fruit shop in DE:

Unser Preis: 184,37 €
…-.which is around 210$

You will find a much much better price through I don’t know about your VAT on the antennas and I know they can handle international shipments, probably though Postal service would be cheapest shipping to anywhere in Europe


did I understand you to reply that a GPS antenna ground plane should be ferrous? If so can you explain why or give references? I just haven’t been able to find any helpful material on this in my searches online.

thanks - Jon

HI Jonathan,

The ground plane needs to be made from an RF reflective material. It doesn’t have to be ferrous.

Allen Crawford

First comparison with homemade cuadrifilar helix and a TW4721…both on a 20 cm diam. copper disc, left 1mm, right 0.1 mm thickness.
what a groundplane really does at a helix antenna, is not easy to describe. Is is not just a mirror for the antenna, but also adding a counterpoise to the feed line, ground noise attenuation and multi-phase supression , and… might even decrease the ‘gain’ by surface waves or reflecting energy in the opposite circular polarization. So, all in all it’s a try and fail operation.

And a TW4721 on a 20 cm diam. 1 mm thick copper disc under a plastic dome (sorry for the quality…):

(I mixed up the TW prod.-id’s, these are the antennas, which came with the kit.)


That is a fascinating test you have made. I was not aware of any home-made GPS antennas.
I am still waiting on the TW3710 to arrive. When I click on the order at it is showing 5/12/16. I have asked Allen Crawford to get the order out faster so I can post results to the community sooner.
Do you have any ideas on how to best do a comparative test when the new antennas arrive? I like the way you did this with the side-by-side home-made antenna and the TW4721.

Hi Ray, to be honest, it is not really a totally faithful test for GPS antennas. Normally I should have taken each antenna and checking the log-data for hours in order to get an idea of multi-path errors (coordinates jumping around).
My test only shows, that the TW4721 gives more stable output ( up to 9 green sats sometimes), with my ant. only up to 3 green sats. I will do some more experiments, but it will be hard to top the TW.:sweat:
What still can be done is decreasing the size of the groundplane up to 10cm diameter, because this is around a half wave length and the minimum, people should have. But I still think, that greater the disc, better the multipath supression (but not yet checked). I will use the 0.1mm copper disc for the Rover and the 1mm copper disc for the Base (where weight is negligible).

Dear Rabun, did your TW3710 arrive? I would be very interested how it compares to the TW4721 (on a groundplane). Currently we’re using TW4721 on 10 cm groundplanes, but I will try bigger planes for the base station at least.


Rubun emailed me that he will receive the TW3710 antennas next week. He plans to do a test of the kit provided TW4721 and the Tw 3710 hopefully next week.


1 Like

I compared two antennas:
TW4721 (10 cm ground plane, plastic cover) vs Magellan NAP100 (which was not designed for GLONASS , but still recieves it)

While the TW4721 gets on average more Sats > 45 SNR.
The Magellan gets sometimes > 50 and generally more Satellites.
The single solution from the TW4721 spreads much more (sd one meter higher).
So I think the Magellan maybe filters better?
Unfortunatly I cant comapre RTK solutions easily…

Here SNR graphs ( TW4721 left, Magellan right):

And Sat vis


Hi all, I am very interested in this topic. I am currently using the stock antennas and made ground planes with raw PCB boards of 10x15cm (they came in this size). Is it better if they are squares of 10x10cm?
The base is mounted on a 1,7m tripod and the rover is mounted on an hexacopter.
I am able to obtain fix but sometimes it takes too long or does not get fix at all after waiting for several minutes.

I see that the number of “green” satellites varies from 4-7 and that is what probably causes that fix takes too long or is not achieved. With a slight improvement of the overall SNR I would get many more satellites.

Do you have any indications for changing the antennas or ground planes (base or rover) to achieve better SNR? I do have limitations because the rover is mounted on a drone.

in this thread ther is some information:

according to the following link - ublox documentation page 20 - you might want to use a square ground plane: