Hf Antenna Height

[Evelio Olivo]

Iwant to set up emlid with coords & an elevation previously obtained for the base point, so that I can capture PPK & broadcast a local NTRIP correction. There are 2 potential entries for antenna heights [tip of pole to base of emlid ant]: one in the manual settings and one at the bottom of the logging settings [attached captures]. For my scenario, should I enter the same ant height in both places? If not, which ant height should be entered: manual or logging settings? What would be the effect of entering the same height for both? Is the antenna phase center [134mm] height automatically included, by the reach app, for a height entered into the manual height settings?

base mode ON218293862 481 KB

logging ant ON19203756 474 KB

I completed some tests, with the emlid, on a tripod, capturing over a control elevation. specifying no antenna HI, within the reach app, for any of the following tests: average single, logging a rinex for opus, and measuring a point in a new survey project all resulted in elevations that were close to the control elevation, if I subtracted the HI after the emlid elevations were calcuated within reach.

When setting up the emlid, as a base, to log PPK data concurrent with an EVO UAV flight, do we specify a height in BOTH the logging settings and with the base coordinates & ellipsoid hgt in the base - configure screen. If not both, which one?

Can you give me an idea of your workflow?

Is your base on a known point or are you establishing your base location? and if so what method are you using to establish your location?

Are you trying to tie your data down to some sort of established local datum?

I use third party antennas with an Emlid Module and it does not know what type of antenna I have connected to it and cannot automatically adjust my pole height to antenna height relative to the physical location of my phase center for me. I have to manually input the measurement to the Phase Center instead of the ARP on my setups.

I wonder why I was getting consistent errors in the elevations I was capturing using my RS2. I took the RS2 unit and took shots at survey benchmarks around my local area and the heights were all out by approximately 134mm (i.e. the antenna height of the RS2) To correct this error I now set my pole height to 1.666 m when in reality it is at 1.8m can anyone explain what I am doing wrong

Where did you get the coordinates of the benchmarks? Please share them and your CSV file with the project with me, so I can check it. You can send the data to sup...@emlid.com if this information is sensitive.

Sorry, just to clarify also, during survey should I add the distance to the base? or the distance to the Phase?

when I export the data I can see another 13cm were added to my data, So I assumed that I should all the time add the measurement to the base of the Antenna?

Is it the same also when I log for 24 hours to establish a BM?

This website gives your cable loss as 2.4dB, which I think is not so high.

Surely getting your antenna higher up and shortening the cable, will give you some range gain, but I am not sure if it is worth the effort.

Please first check maximum achievable range for YOUR LOCATION and ANTENNA HEIGHT by the method given in first post of this thread. If you have already achieved it, it is unlikely that you will get any further increase in range by increasing the antenna height.

Note: Above calculations assume a level terrain without obstructions such as hills, tall trees, tall houses etc.

If the antenna location has above noted obstructions, the range increases considerably when antenna is raised, till it is higher than these obstructions. once at this height, any further increase in height results in little gain at considerable cost & effort.

If your aircraft are mostly at maximum range then this is fine as will go to maximum gain. However if your aircraft are mostly close by the ADS-B signals will saturate the receiver and be missed so lowering your gain will increase the message rate and possibly aircraft.

Values for antenna height above average terrain (commonly abbreviated "HAAT") can be calculated using this form. Two terrain databases are available here: the FCC's legacy 30-second terrain database, and the GLOBE 1 km Base Elevation database from the National Geophysical Data Center. Using GLOBE, HAAT values can be calculated for any location on Earth, given coordinates and an antenna radiation center height above mean sea level (usually correlating to the physical center of the antenna). More about HAAT below the form.

About 10-years ago when I obtained my original GMRS license the FCC had a limit on GMRS antenna height. It was 20 foot above the tree or building to which it was mounted (roughly speaking). In the current regulations that 20 foot limit seems to have been complete removed. Instead, 95.1741 (regarding height) merely redirects to 95.317 that seems to indicate antennae structure over 200 foot may need to be registered with FAA.

The 6.1 meter (20 foot) rule does not apply in this instance. If the height of the structure AND antenna is greater than 200 feet overall it needs to be registered. Several Part 90.20 entities found this out when the FCC cited them.

IIRC the FAA regs state the structure has to have a light at its highest point. It's difficult to get an antenna to work properly when it has a light and power cable on it. The issue was uncovered when antennas started being put on bridges more than towers,

On the simplex front I found I could achieve pretty reliable coverage out 4 to 5 miles where things transitioned to hit and mis out to about 7-8 miles when all seemed to die completely. I expect the reliable range will decrease as foliage comes back. Not bad though for a couple of lower power HT and with good external antennas.

Repeater antenna. No Limit to height in rules. In certain area's around airports FAA regulations limit the tower height. In all locations, towers exceeding 200 feet need to be registered with the FAA and lit with a type accepted lighting system.

Control Stations. Meaning a fixed station (base type station) that is communicating with an off site repeater to extend coverage. I believe is 20 feet (for sure with commercial radios but this run gets broken constantly)

I read about the glue up PITA issue you talked about and was fretting it too. The version I received did not require glue. The couplers simply slide over the lower section and are tightened in place with an allen wrench. Nice!

Those masts are great, although measuring and marking each section and gluing the toggle clamps was a PITA! I have two of them and use the tall tripods from MFJ along with two levels of guy lines to support my G5RV (106' HF antenna) on field days and other club events such as POTA (Parks on the Air) activations.

I have recently bought a 4g Sim Card Router (TP-Link mr6400) and a 4g exterior LTE Antenna. With testing I have now doubled my connection speed. To go one step further, I am looking at the possibility of getting the aerial even higher up my house to chimney level (I'm going to test beforehand). Is there a specific cable other than LTE /4G Antennen-extension cable (i.e. what I'm Googling). What do I need to be looking out for exactly? Also, will there be a loss in signal through a cable of roughly 10 meters, and would it be even noticeable if I were to possibly double my speed again?

Say you use a length of LMR195, which is about 0.5 dB/m at 1800 MHz. By extending the cable 10 m, you'll cause a 5 dB additional loss. You may not get that much additional signal from the increase in height.

What you should do is add a second external antenna. The router has two antenna connectors and LTE uses both in a full MIMO fashion. Adding a second antenna on the mast will allow it to work as designed. It is best to mount the second antenna with the opposite polarisation to the first, but a reasonable vertical separation of 0.5 m will also work. There are also dual-pol antennas in one housing, with two connectors, which will also help.

NOAA's Online Positioning User Service (OPUS) provides free access to high-accuracy National Spatial Reference System (NSRS) coordinates. OPUS uses the same software which computes coordinates for the nation's geodetic control marks and the NOAA CORS Network (NCN).

To use OPUS, simply upload a GPS data file (collected with a survey-grade GPS receiver) to the OPUS upload page. Your computed NSRS position will be emailed to you. If you choose, your position can also be shared publicly on the NGS website, or added to a larger survey project.

Enter the vertical height (in meters) of your Antenna Reference Point (ARP) above the mark. See antenna calibration for a drawing of the ARP for your antenna (usually the center of the base or tripod mount).

Under normal conditions, most positions can be computed to within a few centimeters. However, estimating the accuracy for a specific solution is difficult because formal error propagation is notoriously optimistic for GPS reductions. User errors (such as misidentification of antenna or ARP height) cannot be detected. Local multipath or adverse atmospheric conditions may also negatively impact your solution.

Rapid-Static: The best estimates of coordinate errors are the standard deviations reported by single baseline analysis. Our experiments indicate that the actual error is less than these estimated accuracies more than 95 percent of the time.

Please note: OPUS-RS may perform poorly or fail during periods of high ionospheric disturbance or during the passage of a strong weather front. In general, it is best to avoid collecting GPS data during these events. To avoid collecting data during a geomagnetic storm, see NOAA's Space Weather Prediction Center, which issues geomagnetic storm alerts.

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