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How much salt is there in quality coax?

I'm literally outside testing a second antenna location (below) as my current one is down the gable end and has to be high enough to get above the roof off other houses.

It's janky cause I need better mounts but it's showing promise if I can get more height - this is much lower (as it's ground floor bungalow) and therefore won't need anywhere near as much cable and I'm thinking about sticking router in IP rated enclosure and just run PoE to it saving on cable further.


IMG_20221204_121146.webp
 
For comparison sake, cables go into loft to router.


IMG_20221204_121753.webp
 
I tried twin polarised yagis (adapted from TV aerials) but the parabolic was way way better.
 
So my tests today went pretty well in the new position, the nice thing being that it's a lot lower.

I think I'm going to:
1. Second parabolic grid dish
2. Mimo both parabolics in new position.
3. HDF400 cable
4. IP rated enclosure for mounting router and bulkhead connectors
5. PoE for the lot for shortest possible cabling
6. T K bracket to offset from guttering
 
So my tests today went pretty well in the new position, the nice thing being that it's a lot lower.

I think I'm going to:
1. Second parabolic grid dish
2. Mimo both parabolics in new position.
3. HDF400 cable
4. IP rated enclosure for mounting router and bulkhead connectors
5. PoE for the lot for shortest possible cabling
6. T K bracket to offset from guttering
Sounds like an amazing new year resolution :)
 
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Well, yes. if your current signal level is -97dBm, then you should get -94dBM if you swap the cable for one that has 3dB less attenuation.
The SINR should increase by 3dB as well (which I consider more important than RSRP.

Looking at the data sheets, there is hardly any difference between the LMR-400 and the HDF-400, however, the HDF-400 seems tp cost a lot less than the LMR-400.
So dBm is also a logarithmic measure?
 
Logarithmic scale referenced to power (in milliwatts)

Decibels are otherwise a unit-less measure - so when you’re looking at a system and the various elements in it with loss or gain (expressed in dB) - they are additive or subtractive, to get a total.

Applies in the same way to RF as it does optical communications etc
 
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The SINR should increase by 3dB as well (which I consider more important than RSRP.
Having said that, the SINR is only going to improve if the SINR is dominated by noise. If it is dominated by interference (e.g. from other base stations using the same frequency) and that is more likely in LTE systems, then a low loss cable will not improve the receive SINR and the download speed would not improve. Nevertheless, the transmit power will be higher which should improve the upload speed.
 
It's relative to RF Power (Watts).

1mw is 0 dbm.
That makes more sense. With 3dB of gain, I'd expect to see a 3dBm increase in received power. For some reason I thought that dBm behaved slightly differently and would see a greater increase

So effectively, rotating my dish +45° will give 3dB automatically.
Reducing the length of my cable to 3-4 meters from 9 and replacing with LMR400 will reduce cable losses from 4.2dB to 0.74dB - gain of 3.4dB
I also think the dish feed is in the wrong position for the band, so I think there's another 0.5-1dB of gain to be had there.
 
I suppose it also makes sense that an antenna that has 10dB of gain at 1800MHz like my Iskra P60 antennas, will lose in this case 2.15dB because of the H155 cable (0.43dB/m x 5M) effectively giving me just 7.85dB at the SMA end.

Never considered it that way before. Might also explain why I've never been able to see 5G at all here. The Iskra only has 8.5dB of gain at 3.6Ghz peak, less 3.1dB because of cable loss is only 5.4dB, just obviously not enough to pick up enough signal.

So, in theory, if I were to plug a parabolic dish, straight into my VN007+, shortest possible length of cable possible, there might be a chance of getting 5G N78?

Would be nice to have a spectrum analyser, that way I could see what the antennas are picking up.
 
I suppose it also makes sense that an antenna that has 10dB of gain at 1800MHz like my Iskra P60 antennas, will lose in this case 2.15dB because of the H155 cable (0.43dB/m x 5M) effectively giving me just 7.85dB at the SMA end.

Never considered it that way before. Might also explain why I've never been able to see 5G at all here. The Iskra only has 8.5dB of gain at 3.6Ghz peak, less 3.1dB because of cable loss is only 5.4dB, just obviously not enough to pick up enough signal.

So, in theory, if I were to plug a parabolic dish, straight into my VN007+, shortest possible length of cable possible, there might be a chance of getting 5G N78?

Would be nice to have a spectrum analyser, that way I could see what the antennas are picking up.
It certainly feels like you are missing out on dBs because of the cabling, however even with 5.4dB I expect you should have seen some 5G. Is the VN007+ your only 5G device, can you test with anything else to double check it's not the router?
 
It certainly feels like you are missing out on dBs because of the cabling, however even with 5.4dB I expect you should have seen some 5G. Is the VN007+ your only 5G device, can you test with anything else to double check it's not the router?
To be fair, If there is 5G up there, its going to be weak as ass because I'm so far away - see the coverage check below.

I get 97 RSRP on Band 3 with all the cabling etc on my Iskra. I've always held out hope that a high gain 5G N78 capable antenna would net me enough power to be able to get 5G as I'm directly in the centre of the cell coverage.

Unfortunately, the Iskra is the highest gain 5G antenna I've got apart from my Chinesium dish. Although, I've got another 65cm parabolic and 5G feed that I've not actually tried yet. I might stick that up on top of my second location as high as I can go and test with some really short cabling. Got some 5D-FB left over from a booster so might strap that onto the dish.

I'd love to just strap the VN007 to the dish and try that but would mean having to de-modify the antenna ports which would be a complete drag.

1670256759302.webp
 
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Was bored and remembered I had a nanovna and wanted to see if there was negligible differences in cables.

Below, cheap nasty RG58, approx 2m length, 3.6dB loss at 1800mhz

IMG_20221222_202454.webp


Cheap nasty RF200 cable, approx 2m

IMG_20221222_203058.webp
 
Cheap nasty CCA core 5D-FB cable, approx 5m, 2.6dB loss which was a nice surprise.

IMG_20221222_203227.webp


LMR400 budget friendly cable, 5m worth, 2.13dB loss.

IMG_20221222_203402.webp
 
Interesting, thanks for sharing. I've only used the vna for swr, nice to see it can do this, too.
 
I would like to get a shorter cable for my Iskra P58's, do i need N Type to SMA connector? Someone wanna just link me what i gotta buy. 3-4m should be fine.
 
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