Typically, a field data-collection app used for RTK applications will offer a feature that allows you to input your total antenna height. By telling your data-collection app what your total antenna height is (in meters), you can ensure that you are computing your location at ground level (i.e., where the tip of your survey range pole touches the ground) for high-accuracy elevations. In this article, we will show you how to calculate the total antenna height for the three Arrow GNSS receivers most commonly used for RTK purposes.
When calculating your total antenna height, you will want to take into account three values:
- Range Pole Height
- Antenna Mounting Plate Height
- Antenna Phase Center
For example, the total antenna height of an Arrow Gold® antenna (ANT-L1L2L5) mounted to a standard mounting plate and further mounted to our 2-meter sectional range pole will be this:
2 m (Range Pole) + 0.0253 m (Mounting Plate) + 0.01035 m (Phase Center) = 2.035 m
The range pole height is often provided by your range pole manufacturer. If not, you can measure it with a meter-friendly tape measure. Now, let’s walk through how we got the values for the mounting plate and antenna phase center.
First, let’s define what an antenna phase center is …
What is Antenna Phase Center?
Antenna phase center is the electrical (nonphysical) location where the receiver computes its location. The phase center is derived by a tedious calibration process, performed by organizations such as the U.S. National Geodetic Survey (NGS).
The antenna phase center values for Eos Arrow GNSS receivers are constant values. Below are the antenna phase center values for the three Arrow GNSS antennas that support RTK applications. These antennas come standard with three receivers: the Arrow 200®, Arrow Gold®, and the new Arrow Gold+™.
Find Your Antenna Model
Before you begin, you will need to find your antenna model. To do this, simply look on the underside of your Arrow 200®, Arrow Gold®, or Arrow Gold+™ antenna. Turn over your antenna and look for the model number. It will be either ANT-0504E2 for legacy antennas (for Arrow 200® receivers); ANT-L1L2L5 for newer models (for Arrow 200® and Arrow Gold® receivers); or ANT-FBANT (for Arrow Gold+™) antennas. Depending on whether your antenna came mounted to a plate, the model can be found both on the antenna underside itself or the mounting plate underside.
Find your antenna model number:
Antenna Phase Center and Mounting Plate Height Values
The following are the phase center values for standard antennas included with your Arrow 200®, Arrow Gold® and Arrow Gold+™
Legacy Arrow 200® Antenna Values (Model ANT-0504E2)
The antenna phase center for legacy Arrow 200® receiver antennas (model ANT-0504E2) is 0.0698 m. The height of the mounting plate supplied by Eos for this antenna is 0.0253 m.
For the very curious, the calculation we used to get these phase center and mounting plate measurements looks like this:
So if you mount a legacy Arrow 200® antenna (model ANT-0504E2) to a 2-meter range pole, you would simply add all three values to calculate your total antenna height: 2.0951 m.
2 m (Range Pole) + 0.0253 m (Mounting Plate) + 0.0698 m (Phase Center) = 2.0951 m
Current Arrow 200® and Arrow Gold® Antenna Values (Model ANT-L1L2L5)
The phase center for all current Arrow 200® and Arrow Gold® antennas (ANT-L1L2L5) is 0.01035 m. The Eos supplied mounting plate height is 0.0253 m.
Once again, the calculation we used to get to these phase center and mounting plate measurements looks like this:
So if you mount your new Arrow 200® or Arrow Gold® antenna (model ANT-L1L2L5) to a 2-meter range pole, this would be your total antenna height: 2.035 m.
2 m (Range Pole) + 0.0253 m (Mounting Plate) + 0.01035 m (Phase Center) = 2.035 m
Arrow Gold+™ Antenna Phase Center (ANT-FBANT)
The phase center for all Arrow Gold+™ antennas (ANT-FBANT) is 0.0357 m. The height of the mounting plate supplied with the FB-ANT is 0.0253 m.
The calculation we used to get to these phase center and mounting plate values looks like this:
So if you mount your new Arrow Gold+™ antenna to a 2-meter range pole, this is your total antenna height:
2 m (Range Pole) + 0.0253 m (Mounting Plate) + 0.0357 m (Phase Center) = 2.061 m
Summary
Please note: In these examples, we have used a 2-meter range pole height from our Eos 2m sectional, carbon fiber pole (POL-2MC4). If using a different range pole, please make sure to measure precisely the height before computing. Also note that in all three cases, the antenna phase center is measured from the bottom of the antenna housing itself and does not include the thickness of the mounting plate.
Add your three values together — remember to use meters as the unit — and you will have your true total antenna height. This is the value you will want to enter into your data-collection app before beginning RTK data capture.
Lastly, do not add the antenna height in both Eos Tools Pro and in your data collection app. The preference goes to entering this value only in your field app if it offers this feature. This is what it would look like to add your total antenna height into a data-collection app such as Esri’s ArcGIS Field Maps:
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