Ultimate LRS 40 km setup

Introduction

An ULRS user has achieved 40 km distance with telemetry, and says he was only limited by his plane’s autonomy. His setup is the following :

ULRS Modules

Normal Orange 1W modules without increased power (3.3V operation, about 400 mW power)

Antennas

RC

DIY 4 elements Yagi antenna on the ground – DIY Vee antenna on the plane What certainly contributed to the range is that the antennas are precisely tuned with professional equipment :YagiVeeYagi2

Video

For the video, he’s using well tuned vee antennas in the plane, and a patch antenna on the ground :IMG2014111_7279095_14741612IMG2014111_5299503_14741614IMG_20150624_224755_360IMG_20150325_195226_682

Where to find these antennas ?

Have a look at this site,you can also find them on ebay here.

If you want to go still farther

Antennas

Have a look at this 10 elements yagi. Or this 7 elements yagi Or this $75 12 elements 14 dBd (=16.15 dBi) yagi

Calculations

Given that the user did 40 km with a 4 elements yagi (something like 7.6 dBd = 9.75 dBi), using this last 12 elements yagi would provide a gain of 14-7.6=6.4 dB or more than double the distance (80 km).

In addition, running the RFM module at 5.5V would go from 400mW (26dBm) to minimum 800mW (29dBm), which gives 3 dB, or 40% more distance.

So it should go to 80 * 1.4 = 112 km. And given that the user said 40 km was not the system’s limit, but his plane limit, the maximum distance is still more…

3 comments

  1. Meysam says:

    Rc jiamir = rc jammer
    Soory

  2. Neil says:

    Hi, I see you used 1.2Ghz here, I am currently using DTF and want to move to UltimateLRS so will need to buy some different modules. I’m thinking of the Wolfbox TX and RX units but do you know if they have built-in low pass filters or not?

    Thanks!

    • admin says:

      They don’t have filter, but they’re less noisy than DTF modules (check the spectrum analyzer page on the site).

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