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Publi

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  1. Update on the project: I figured it might be a problem with the thickness of the plate, considering that internal reflections could be added in WinProp and counted as 1 ray. However, simulating with different thicknesses (1cm, 50 cm, 5m, ...) I consistently get the same results. I am starting to suspect that there might be an issue with the resulting phase and thus the size of the resulting field.
  2. Hi everyone, terribly sorry for the late response; I forgot to switch on "notify me of replies". First af all I want to thank both of you for checking my issue and for your input! @mvogel 1) I excluded diffracton from the results for the reason you mention and also to verify the theoretical result with the simulation, so that shouldn't be a problem. I have indeed selected coherent superposition. Yes, that is true, however I find that the critical distance is lower for low antenna's, so if I'm correct I should be well over this distance. @mvogel 2) At this time the exclusion is at -200 dB, but I will try to play with this number a bit. I'm not sure this will help though, because when I view the .str file, with all the point and ray data, I find that direct en reflected ray are closely related. @reinerh I felt as though this was the reason as well, I wonder if there is something I can do to increase the accuracy of this angle? I am not actually using this model to describe the parking garage. I did measurements in this garage and got more or less 33 dB attenuation. I then tried to simulate this same environment and compare the results. Because there was such a big difference I assumed I was doing something wrong. So after many new simulations where I changed numerous parameters (material properties, frequency, radiation pattern, ...), I tried taking one step back and starting from the beginning, just to see where I made a mistake.I was going to simulate theoretically known situations and conforming the data with my calculations. I started with free space simulation, which was perfectly correct and corresponding with the theoretical expected values. Then I moved on to the 2-ray model and this was almost completely correct as well, however I noticed that as I lower the antenna, while keeping critical distance in mind, the attenuation started to deviate more and more fro the theoretical values. So because I could confirm both situations I knew that my databases and other settings were more or less correct, but when only changing antenna heights, I got worse and worse results.
  3. Hello For a real implementation, I am running simulations of a certain area (parking garage) where the antenna is only 15 cm above the floor plate. I noticed that the results of my measurements differ very strongly from the values I find in the simulation. To check if I had made a mistake I tried to recreate the 2-ray path model using a floor plate with normal material properties (for example concrete). This was successful because the resulting power (and field strength) values decreased with 40 dB per decade as we expect from the theoretical explanation. This of course after the oscillations stop (> critical distance). However, when I rerun this simulation with lower antenna heights (coming from 5 m to 0.5 0 or even 0.15 m) the results get worse and worse. The lower I place my antenna (but still above the floor obviously) the worse my results get. At 0.15 m antenna (and resulting prediction height) I get just over 20 dB/decade. I have graph where I simulated the exact same plate, exact same antenna location, but with adjusted antenna and prediction heights where you can see this trend. I feel as though there is something wrong with either the interaction between the antenna and the floor (incorrect resulting radiation pattern) or that the separate rays don't add up correctly at the resulting point when they are this close together. I have tried this with several material properties but I still get this result. Any help would be much appreciated. Kind regards Publi PS: to recreate the results: Step 1: create database in WallMan, long plate (>2km) of a certain with with 5.5 relative permittivity and 0.01 S/m conductivity. Step 2: Make SRT project and load this into ProMan. Step 3: Place an antenna with normal gain and isotropic radiation pattern and arbitrary transmitted power at the start of the plate. Choose for example 10 m height (also for prediction plane). Step 4: Simulate it and plot the resulting power from the transmitter to the end of the plate. Step 5: Confirm that you have 40 dB/decade power loss. Step 6: Repeat starting from step 3 but now choose a lower antenna height and prediction plane. Confirm that you power loss is now lower than the first case. 2Ray-AntennaHeights.eps
  4. When I utilize your formula for the breakpoint I get 848 m (I used 1 GHz). I also understand the reason for these oscillations and the way the last minima is calculated (although I use the same formulae without Pi, but for my question this should not matter as we are discussing the part of the graph long after this point). However the problem I encounter is that after this last breakpoint the received power should decrease with 40∙log(distance) as you have stated, and I agree. But when I simulate using the same parameters the power after the last breakpoint does not decrease with 40∙log(distance) but instead it decreases with 16∙log(distance), as you can see in the attachment. The lower I place my antennas, the worse this deviation gets. Is this due to the fact that for very low incidence angles, ProMan can no longer make the distinction between 2 rays that are actually direct path and reflected ray?
  5. Hello everyone As a part of some simulations I am running, I tried to simulate a 2-ray path model in ProMan. To achieve this I approximated a PEC in WallMan ( εr =1 (lowest possible), µr = 1, σ = 6e+006 (highest possible)) as a floor plate. In ProMan I simulated an antenna at one end (height 4.5m) and I plotted the received power vs the distance at height 4.5m. Everything about this graph is correct, the locations of the oscillations are exactly where I would suspect them theoretically and once Δ R drops below λ /2 the oscillations stop and I get a constant slope. However due to the small incidence angle and the relative height of the transmitter and respective receiver, I would predict the path loss of this slope to be 4 (40 dB/decade decrease, which I should get regardless of material properties because the angle is so small and I only have the direct ray and the reflected ray). But I never get this value from the simulations. The lower I place my transmitter, the lower the path loss gets. The path loss from every simulation has been lower then the expected value. Does anyone know the reason for this deviation or is someone struggling with the same phenomena? I tried to look for an answer in the manual and found a possible cause for my mismatch. I suspect that my tolerance for the angle of incidence is to low. Therefore ProMan has trouble correctly interfering these two rays. I found a page in the manual, from which I have included a print screen, where oen could adjust this value. However I haven't been able to locate this menu for my simulations. Thanks in advance! Kind regards Publi
  6. Hello Reinerh Thanks for your response! I understand that the material properties are considered for all interactions, and so the values of the transmission matrix are influenced by the material properties. But i'm having trouble to see how the values in the transmission matrix are generated, how they are calculated? For example for the direct ray the material properties do not matter, how is the transmission matrix generated in that case? And what if there is a reflection? I'm sorry if i'm missing something here. Kind regards Publi
  7. Hello everyone I had some trouble understanding the transmission matrix that ProMan generates. However I found some explanation on this forum which helped me a lot. There is still something i do not understand about this. This other post said the matrix was made independent of the antenne's polarization. But then what does ProMan use to generate these values, how are they calculated? Do they take into account the material properties (for example when there is a reflection)? Thanks in advance for any help! Kind regards Publi
  8. Dear Reinerh I had presumed as much but wanted to be sure, thank you for the information! Kind regards Publi
  9. Dear Reinerh Thank you very much for the quick response. I do seem to have made a mistake in that part, great catch! Kind regards Publi
  10. Dear All I recently encountered the error from the picture, "Error 953: Not enough interactions (total number) specified". I have had this error before without any actual problems in my simulation. However this time it seems that my simulation stopped calculating way before my prediciton area was filled. I have a long and small prediciton area (1 m wide and 50 km long) but it stops showing values for received power or field strength after 1020 m. Is this just the limit for how many points ProMan can simulate? I have the resolution at 10m so it has the same amount of data points as my previous predictions which are shorter but at a higher resolution (for example 0.2m resolution). Is this related to the error or do I have 2 seperate breaches of conditions? Thanks in advance! Publi
  11. Hello everybody I have been using ProMan for a while now but for certain simulations I get some serious deviations from the theoretical values that I calculated. To identify the reason for this difference I wanted to see the phase of every wave that contributes to the field strength of a point. However the log files that are generated only contain information about the path, transmission matrix, delay, field strength components and so on. I can calculate the phase difference between several paths (for example one direct path and a reflection) based on the delay and path length difference between them but i can't seem to find exact phase information for each path. Is there a way to gather the phase from a path, wether indirect or direct, or does ProMan not have such a mechanism? For the simulation I checked that the superposition of contributions is coherent and considers the phase. These mismatches are mainly present when there are reflections. Thanks in advance. Publi
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