Strong Antennas to Listen to Frequencies 80 miles - 220 miles (130km - 350km) Away

[RadioScannerSA]

Hi

I live in South Africa, Gauteng.
But I want to listen to repeaters that are in other provinces.
I live in a city with many buildings and the sort around me.

The frequency range I'm looking for is: 150-165 MHz.

Is there some powerful antenna I can put on a roof (not too worried about the price) that could pick up frequencies from that far? Or is it all based on the strength of the repeater or the base radio itself that are sending out the signal?

I want an antenna that can connect to the SDS100.

Thanks!

 

[vagrant]

Buildings in the way will be a problem. Additionally, one must consider line of sight. If the repeaters are 2000 meters above ground you would have a chance at the 130km one.

Line Of Sight Calculator

calculators, engineering calculators....

www.calculatoredge.com

 

[RadioScannerSA]

I took the coordinate's height above sea level of both the repeater and my home, and I put the measurements on that website. Is that right?



But I still can't pick it up, even though the distance of line of sight shows a lot more than needed, is this before of the antenna?

 

[buddrousa]

Antenna 1 should be your site.
Antenna 2 should be the site you want to hear.

 

[vagrant]

Is there terrain in the way between you and that particular repeater? You also mentioned buildings. A yagi antenna covering that frequency span will help, but an omni-directional may be able to do it. Still, there is the concern of the modulation used and what modulation your scanner can receive. Also, if the signal is encrypted that will be a problem.

 

[Ubbe]

I have used this map to check if the terrain will allow a communication. https://www.scadacore.com/tools/rf-path/rf-line-of-sight/
There are others that also consider known buildings in the path, I think it was Google Map/Earth based.

/Ubbe

 

[prcguy]

I've done a 150mi path from a 4,000ft mountain top to a 5,700ft mountain top on UHF and it worked but not very well. Unless you are on a taller mountain than 5,700ft listening to a station on a taller mountain than 4,000ft you will not get anything near 220mi range.

 

[IC-R20]

The buildings in the way pretty much kill off any chance of that as well as the SDS100, it's not a very sensitive radio specially on VHF. Otherwise I've easily pulled that off on VHF before using the WS1040 and a 3 element yagi over a a couple mountain ridges. Generally though you want the site you're already receiving to have decent power and with the antenna in a nice elevated position.

 

[RadioScannerSA]

Hi,

So I've measured the distance from the repeater to my house using https://www.scadacore.com/tools/rf-path/rf-line-of-sight/, this shows a green line, so technically I should get those frequencies?


I have the WS1040 too, so if I buy Yagi 3-Element Antennas 7 dB 380 : 470 MHz - Webb Industries it should, on paper, pick those frequencies up? However, I'm more interested in the 150-165 MHz range, where this shows 380-470. Which antenna should I look at?

From what I understand, the different operators in that area have private frequencies and then the repeater redistributes each of them. It's not one repeater frequency. Will that still work?

 

[mmckenna]

it should, on paper, pick those frequencies up?

There's more to this than just making sure you have line of sight. RF attenuates in free space, so you'll be fighting that, also.
You might want to play around with one of the online free space loss calculator tools:

Free Space Path Loss Calculator (FSPL) - everything RF

www.everythingrf.com

You can add lots and lots of gain at your end with Yagi antennas, amplifiers, low loss coax, etc. but if they are not transmitting with a lot of power and with higher gain antennas on the far end, you'll have issues.

Consider that you may also end up dealing with co-channel interference, or adjacent channel interference, which can cause issues for your receiver.

 

[Ubbe]

The free space attenuation are theoretically 136dB at 450Mhz and 126dB at 150MHz. The lowest possible signal to receive are -110dBm in the scanner. The transmitter site ,if they use an omni antenna, probably has an output of +40dBm or more so it should be possible to receive a good signal even with the scanners own antenna if you are outside and free from any buildings or trees blocking the signal.

/Ubbe

 

[vagrant]

1. What mode is being used by the repeaters you want to monitor? For example FM, DMR, or something else?
2. Are those repeaters using encryption?
3. How many watts are they using?
4. Your line of sight looks good, but is there a building, or buildings, between you and the repeater?
5. Do you have an FM broadcast radio station nearby and or a paging transmitter that often uses frequencies near 152 MHz?

The RF line of sight is just the start of understanding your RF environment. Basically, if you stand on the roof of your home/building and the supplied scanner antenna, keeping it vertical, does not receive the signal now, then a yagi or log periodic directional antenna may not be sufficient. Seriously, standing on your roof with your scanner is a first step. No signal will save you time and money on an antenna, coaxial cable, filters, amplifier, etc. If the signal is weak/intermittent then you may improve it. By the way, how many feet or meters would the coaxial cable need to be from your scanner location and your roof?

 

[dlwtrunked]

I took the coordinate's height above sea level of both the repeater and my home, and I put the measurements on that website. Is that right?
View attachment 152353
View attachment 152354

But I still can't pick it up, even though the distance of line of sight shows a lot more than needed, is this before of the antenna?

Height is supposed to be above average terrain and not sea level. Using sea level will give you wrong extremely large distances. I am surprised no one pointed that out.

 

[nd5y]

The scadacore tool is not reliable for long distances...