Re: EMF Calculator

Andy G4JNT

Robert, you didn't quote your frequency, but back-calculating I reckon your 10m dish is on 3.4GHz to give 50dBi
In which case the beam width is around 0.5 deg.
SO it's quite reasonable to suppose that at 18m in that narrow beam you are getting a few milliwatts per sq. cm.

You can work it out from first principles.  It's only basic physics.  But for high powers in that narrow beam the safe distance could well be some way off.   But they do need to be standing in it for 6 minutes - and even the Moon moves faster than that.

I agree for large dishes the feedhorn is the antenna.   Since a large dish will probably have a feedhorn designed for 10% spillover, use a value of -10dBi as the antenna gain  - unless you really believe someone will sit in the dish :-)

Andy

On Fri, 23 Apr 2021 at 19:53, Robin Szemeti - G1YFG <robin@...> wrote:
Just ignore it, you won't get anything sensible or useful out of that spreadsheet for microwaves. The calculations don't work for parabolic reflectors at close range.  They assume a point source.  Do the calculations for 2W on a 10M  50dBi dish and it will tell you the safe distance as being 18m ... it should be (fairly) obvious that with 2W spread over a 10m dish, you could sit in the dish itself without harm for months.

To get a more sensible result, you should probably use the gain of the feedhorn, and look at the safe distance from the feedhorn, not the reflector ... assume a 10dBi gain on the feedhorn, and you get the safe distance as 0.2m ... so providing you don't spend too long transmitting while a member of the public has their head between the feedhorn and hte dish, you should be fine.

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

--
Robin Szemeti - G1YFG

Re: EMF Calculator

Robin Szemeti - G1YFG

Just ignore it, you won't get anything sensible or useful out of that spreadsheet for microwaves. The calculations don't work for parabolic reflectors at close range.  They assume a point source.  Do the calculations for 2W on a 10M  50dBi dish and it will tell you the safe distance as being 18m ... it should be (fairly) obvious that with 2W spread over a 10m dish, you could sit in the dish itself without harm for months.

To get a more sensible result, you should probably use the gain of the feedhorn, and look at the safe distance from the feedhorn, not the reflector ... assume a 10dBi gain on the feedhorn, and you get the safe distance as 0.2m ... so providing you don't spend too long transmitting while a member of the public has their head between the feedhorn and hte dish, you should be fine.

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

--
Robin Szemeti - G1YFG

Re: N switch.

Colin Ranson

Thanks Alwyn,

I give those a go.

Colin de G8LBS.

Sent from Mail for Windows 10

From: alwyn.seeds1
Sent: 23 April 2021 08:05
To: UK Microwaves groups.io
Subject: Re: [UKMicrowaves] N switch.

Dear Colin,

Rather than use switches, I have good low pass filters on all transmit outputs and good band-pass filters on all receiver inputs.

That way you can transmit on any band and receive on any other band without desensitisation or the risk of front-end burn out.

At my station, this is also necessary to avoid interference to/from co-located and nearby other services.

If you need coaxial switches, Sage made N-Type switches that are good to X-Band; sometimes available surplus.

The switches sold to amateurs are OK up to 70cm, if you are not using high power, but not great above.

Regards,

Alwyn G8DOH

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.

SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.

_____________________________________________________

Re: EMF Calculator

Martyn G3UKV

My thoughts EXACTLY. Invisible ink even better.
73 Martyn G3UKV

On 23/04/2021 10:27, Andy G4JNT wrote:
They're just stored at home
Which means any I bother to do may well will be written on the back of a used envelope in green ink

Everyone's all taking this far too seriously.

Andy

On Fri, 23 Apr 2021 at 10:23, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:
The thing that I don’t understand is what is done with the assessments. Are they stored at home  in case they are asked for or do they have to be submitted to Ofcom and updated when necessary.
Dave G4GLT.

On 22 Apr 2021, at 14:39, SAM JEWELL via groups.io <jewell=btinternet.com@groups.io> wrote:

﻿That should, of course read wary. Not unwary!
Sam

Sent tomorrow from my time machine

On 22 Apr 2021, at 14:30, SAM JEWELL via groups.io <jewell=btinternet.com@groups.io> wrote:

﻿Being a little unwary of computer EMF models/calculators for ICNIRP, I have been doing some measurements on my 23cm EME system, using a calibrated portable spectrum analyser and an antenna with a known antenna factor. The results have been interesting and do actually bear out some of the calculated numbers.
I felt that I would be happier knowing actual W/m2 levels at points of public access near my premises, on the bands above 1GHz, rather than relying completely on calculated values in a highly complex environment, where vegetation, fences and relative access height are all factors that affect the real levels.

73 de Sam, G4DDK

On 22 Apr 2021, at 14:06, Roger Ray via groups.io <g8cub=yahoo.co.uk@groups.io> wrote:

﻿I suggested before a simple pir to turn off the tx, if someone is standing in front of the dish. You would not be communicating then anyway.
Seems like a good idea particularly to stop someone looking down the waveguide, while you are sorting another problem.
I am intending to do some real life measurements against icnirp levels with a Narda s3 personal monitor, especially for the bands above 10GHz. As it will be near field the calculator is not a lot of use, even if it worked above 10G.
Roger
G8CUB

On 22 Apr 2021, at 10:08, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

﻿Thanks Andy,
Great. That makes it all seem a lot easier.
73
Dave G4GLT.

On 22 Apr 2021, at 09:59, Andy G4JNT <andy.g4jnt@...> wrote:

﻿
Just don't transmit with anyone standing in front of the dish - and if you feel you must, write down that that would be the case.   No need to rope off
You wouldn't have anyone standing there for 6 minutes while you're working anyway, would you.

Andy

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

 Virus-free. www.avg.com

Re: EMF Calculator

Stephen Tompsett

Having done assessments for my home systems it would appear that at VHF/UHF/SHF most people should have little or no problem as long as the antenna is mounted at or above roof level, even when running full legal power...

This probably also applies for the higher HF bands using dipoles/yagis, where it may be possible to approximate the antenna as a point source, but the calculator appears to be totally inappropriate for 'long wire' and similar antennas.

On 23/04/2021 10:27, Andy G4JNT wrote:
They're just stored at home
Which means any I bother to do may well will be written on the back of a used envelope in green ink

Everyone's all taking this far too seriously.

Andy

On Fri, 23 Apr 2021 at 10:23, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:
The thing that I don’t understand is what is done with the assessments. Are they stored at home  in case they are asked for or do they have to be submitted to Ofcom and updated when necessary.
Dave G4GLT.

On 22 Apr 2021, at 14:39, SAM JEWELL via groups.io <jewell=btinternet.com@groups.io> wrote:

﻿That should, of course read wary. Not unwary!
Sam

Sent tomorrow from my time machine

On 22 Apr 2021, at 14:30, SAM JEWELL via groups.io <jewell=btinternet.com@groups.io> wrote:

﻿Being a little unwary of computer EMF models/calculators for ICNIRP, I have been doing some measurements on my 23cm EME system, using a calibrated portable spectrum analyser and an antenna with a known antenna factor. The results have been interesting and do actually bear out some of the calculated numbers.
I felt that I would be happier knowing actual W/m2 levels at points of public access near my premises, on the bands above 1GHz, rather than relying completely on calculated values in a highly complex environment, where vegetation, fences and relative access height are all factors that affect the real levels.

73 de Sam, G4DDK

On 22 Apr 2021, at 14:06, Roger Ray via groups.io <g8cub=yahoo.co.uk@groups.io> wrote:

﻿I suggested before a simple pir to turn off the tx, if someone is standing in front of the dish. You would not be communicating then anyway.
Seems like a good idea particularly to stop someone looking down the waveguide, while you are sorting another problem.
I am intending to do some real life measurements against icnirp levels with a Narda s3 personal monitor, especially for the bands above 10GHz. As it will be near field the calculator is not a lot of use, even if it worked above 10G.
Roger
G8CUB

On 22 Apr 2021, at 10:08, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

﻿Thanks Andy,
Great. That makes it all seem a lot easier.
73
Dave G4GLT.

On 22 Apr 2021, at 09:59, Andy G4JNT <andy.g4jnt@...> wrote:

﻿
Just don't transmit with anyone standing in front of the dish - and if you feel you must, write down that that would be the case.   No need to rope off
You wouldn't have anyone standing there for 6 minutes while you're working anyway, would you.

Andy

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

```--
Stephen Tompsett (G8LYB)
Tel: 01788 578940
Mob: 07956 855816```

Re: EMF Calculator

Andy G4JNT

They're just stored at home
Which means any I bother to do may well will be written on the back of a used envelope in green ink

Everyone's all taking this far too seriously.

Andy

On Fri, 23 Apr 2021 at 10:23, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:
The thing that I don’t understand is what is done with the assessments. Are they stored at home  in case they are asked for or do they have to be submitted to Ofcom and updated when necessary.
Dave G4GLT.

On 22 Apr 2021, at 14:39, SAM JEWELL via groups.io <jewell=btinternet.com@groups.io> wrote:

﻿That should, of course read wary. Not unwary!
Sam

Sent tomorrow from my time machine

On 22 Apr 2021, at 14:30, SAM JEWELL via groups.io <jewell=btinternet.com@groups.io> wrote:

﻿Being a little unwary of computer EMF models/calculators for ICNIRP, I have been doing some measurements on my 23cm EME system, using a calibrated portable spectrum analyser and an antenna with a known antenna factor. The results have been interesting and do actually bear out some of the calculated numbers.
I felt that I would be happier knowing actual W/m2 levels at points of public access near my premises, on the bands above 1GHz, rather than relying completely on calculated values in a highly complex environment, where vegetation, fences and relative access height are all factors that affect the real levels.

73 de Sam, G4DDK

On 22 Apr 2021, at 14:06, Roger Ray via groups.io <g8cub=yahoo.co.uk@groups.io> wrote:

﻿I suggested before a simple pir to turn off the tx, if someone is standing in front of the dish. You would not be communicating then anyway.
Seems like a good idea particularly to stop someone looking down the waveguide, while you are sorting another problem.
I am intending to do some real life measurements against icnirp levels with a Narda s3 personal monitor, especially for the bands above 10GHz. As it will be near field the calculator is not a lot of use, even if it worked above 10G.
Roger
G8CUB

On 22 Apr 2021, at 10:08, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

﻿Thanks Andy,
Great. That makes it all seem a lot easier.
73
Dave G4GLT.

On 22 Apr 2021, at 09:59, Andy G4JNT <andy.g4jnt@...> wrote:

﻿
Just don't transmit with anyone standing in front of the dish - and if you feel you must, write down that that would be the case.   No need to rope off
You wouldn't have anyone standing there for 6 minutes while you're working anyway, would you.

Andy

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

Re: EMF Calculator

Dave

The thing that I don’t understand is what is done with the assessments. Are they stored at home  in case they are asked for or do they have to be submitted to Ofcom and updated when necessary.
Dave G4GLT.

On 22 Apr 2021, at 14:39, SAM JEWELL via groups.io <jewell@...> wrote:

﻿That should, of course read wary. Not unwary!
Sam

Sent tomorrow from my time machine

On 22 Apr 2021, at 14:30, SAM JEWELL via groups.io <jewell@...> wrote:

﻿Being a little unwary of computer EMF models/calculators for ICNIRP, I have been doing some measurements on my 23cm EME system, using a calibrated portable spectrum analyser and an antenna with a known antenna factor. The results have been interesting and do actually bear out some of the calculated numbers.
I felt that I would be happier knowing actual W/m2 levels at points of public access near my premises, on the bands above 1GHz, rather than relying completely on calculated values in a highly complex environment, where vegetation, fences and relative access height are all factors that affect the real levels.

73 de Sam, G4DDK

On 22 Apr 2021, at 14:06, Roger Ray via groups.io <g8cub@...> wrote:

﻿I suggested before a simple pir to turn off the tx, if someone is standing in front of the dish. You would not be communicating then anyway.
Seems like a good idea particularly to stop someone looking down the waveguide, while you are sorting another problem.
I am intending to do some real life measurements against icnirp levels with a Narda s3 personal monitor, especially for the bands above 10GHz. As it will be near field the calculator is not a lot of use, even if it worked above 10G.
Roger
G8CUB

On 22 Apr 2021, at 10:08, Dave via groups.io <davidnewman55@...> wrote:

﻿Thanks Andy,
Great. That makes it all seem a lot easier.
73
Dave G4GLT.

On 22 Apr 2021, at 09:59, Andy G4JNT <andy.g4jnt@...> wrote:

﻿
Just don't transmit with anyone standing in front of the dish - and if you feel you must, write down that that would be the case.   No need to rope off
You wouldn't have anyone standing there for 6 minutes while you're working anyway, would you.

Andy

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

Re: N switch.

alwyn.seeds1

Dear Colin,

Rather than use switches, I have good low pass filters on all transmit outputs and good band-pass filters on all receiver inputs.

That way you can transmit on any band and receive on any other band without desensitisation or the risk of front-end burn out.

At my station, this is also necessary to avoid interference to/from co-located and nearby other services.

If you need coaxial switches, Sage made N-Type switches that are good to X-Band; sometimes available surplus.

The switches sold to amateurs are OK up to 70cm, if you are not using high power, but not great above.

Regards,

Alwyn G8DOH

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.

SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________

Re: N switch.

KENT BRITAIN

In a C connector named after it's developer  Carl Concleman (Think I spealed that right) the inductance in the pins is tuned out with the shaped Teflon in the connector.   So it is a  cap-inductor-cap low pass filter tuned to about 4 GHz.
Great low loss connector ....... below 4 GHz.        Oh yea, and the Type N is named after Paul Neil who developed that connector.    Later Paul and Carl worked together to develop the Bayonet Neil Concleman  BNC and later the Threaded Neil Concleman TNC connectors.     That a Type N male fits on a female BNC or TNC is not an accident. Paul did the mechanics on all three.   Kent WA5VJB/G8EMY

Absolutely have no idea where  British Naval Connector came from.

On Thursday, April 22, 2021, 05:20:05 PM CDT, Alan Beard via groups.io <beardal@...> wrote:

Hi Colin,

We all know the BNC connectors. What about the "C" connectors?

Also bayonet but of similar size to the N connectors.

Alan VK2ZIW

On Thu, 22 Apr 2021 22:36:11 +0100, Dave (G1OGY) wrote
> Hello Colin
> For a similar function I use a CX-520 relay fired off by the PTT
> output (ground) on TX
> A secondary bonus is that the relay could switch to a 50Ohm load
> rather than leaving the 2M kit with an O/C input.
>
> Dave, G1OGY
>
> On Thu, 22 Apr 2021 at 14:06, Colin Ranson <g8lbs@...> wrote:
> >
> > Hi all,
> >
> >
> >
> > Somewhere, long distant past, [UTF-8?]Iâ€™m sure I came across an N plug to
N socket adapter with a bayonet like action in the middle barrel to connect or
disconnect the signal path as needed.  Could do with something like it low
loss to prevent my 150w 4m from overloading my 746 on 2m.  At the moment I
disconnect the 2m N plug from the patch board. Anyone know of such a thing ?
> >
> >
> >
> > Best regards to all,
> >
> >
> >
> > Colin de G8LBS.
> >
> >
> >
> >
> >
> > Sent from Mail for Windows 10
> >
> >
> >
> >
>
>

---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.

Re: N switch.

Alan Beard

Hi Colin,

We all know the BNC connectors. What about the "C" connectors?

Also bayonet but of similar size to the N connectors.

Alan VK2ZIW

On Thu, 22 Apr 2021 22:36:11 +0100, Dave (G1OGY) wrote
Hello Colin
For a similar function I use a CX-520 relay fired off by the PTT
output (ground) on TX
A secondary bonus is that the relay could switch to a 50Ohm load
rather than leaving the 2M kit with an O/C input.

Dave, G1OGY

On Thu, 22 Apr 2021 at 14:06, Colin Ranson <g8lbs@hotmail.com> wrote:

Hi all,

Somewhere, long distant past, [UTF-8?]Iâ€™m sure I came across an N plug to
N socket adapter with a bayonet like action in the middle barrel to connect or
disconnect the signal path as needed. Could do with something like it low
loss to prevent my 150w 4m from overloading my 746 on 2m. At the moment I
disconnect the 2m N plug from the patch board. Anyone know of such a thing ?

Best regards to all,

Colin de G8LBS.

Sent from Mail for Windows 10

---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.

Re: N switch.

Dave (G1OGY)

Hello Colin
For a similar function I use a CX-520 relay fired off by the PTT
output (ground) on TX
A secondary bonus is that the relay could switch to a 50Ohm load
rather than leaving the 2M kit with an O/C input.

Dave, G1OGY

On Thu, 22 Apr 2021 at 14:06, Colin Ranson <g8lbs@hotmail.com> wrote:

Hi all,

Somewhere, long distant past, I’m sure I came across an N plug to N socket adapter with a bayonet like action in the middle barrel to connect or disconnect the signal path as needed. Could do with something like it low loss to prevent my 150w 4m from overloading my 746 on 2m. At the moment I disconnect the 2m N plug from the patch board. Anyone know of such a thing ?

Best regards to all,

Colin de G8LBS.

Sent from Mail for Windows 10

Re: typical

militaryoperator

thats typical Ben I took down 23cm last night ready to start putting the 4 shf bands up for tuesday bad timing. Im still at work now but guess the majority are now back supporting the poor local landlords HI
73 Chris G0WUS

I find this 4 band night a pain Chris. Really should be separate nights, why is only Tuesday used?

I hear many say they dont have this or that ant up. I for one could not put all 4 on my pole at one time and there's no point in changing half way through as all the early birds have gone.

I had 9 and 3 last time, might try 13 next but obviously as we all know, basically is immaterial, all I can do is try and spot some dx contacts, hi.

Hey ho.

cheers, Ben G4BXD

Re: First two way contact on 30THz in UK

Julian G1EKW

Hi Barry,

Thanks for that confirmation, pretty much what I thought.

I look forward to further details of this contact. Thanks for the heads-up.

Julian.

Re: typical

Chris G0WUS

thats typical Ben I took down 23cm last night ready to start putting the 4 shf bands up for tuesday bad timing. Im still at work now but guess the majority are now back supporting the poor local landlords HI

73 Chris G0WUS

On 22/04/2021 14:35, militaryoperator via groups.io wrote:
Tuesday, copying the IOW beacon on 23 at S2, today its S6/7 but there's no one on.

A few on KST but obviously not watching their screens!

Ben.

_._,_._,_

You receive all messages sent to this group.

_._,_ ._,_

Re: First two way contact on 30THz in UK

Barry Chambers

Julian

my receive sensors work in the 5.5 to 14um range. The human body is a good IR source at about 10um.

Barry, G8AGN

On 22/04/2021 16:28, Julian G1EKW wrote:

Unless my physics and elementary arithmetic have somehow combined to thwart my interpretation, that puts it right in the centre of the so-called "Molecular Fingerprint" area of the mid-IR spectrum.

```--
73
Barry, G8AGN```

Re: First two way contact on 30THz in UK

Julian G1EKW

Unless my physics and elementary arithmetic have somehow combined to thwart my interpretation, that puts it right in the centre of the so-called "Molecular Fingerprint" area of the mid-IR spectrum.

Re: EMF Calculator

SAM JEWELL

That should, of course read wary. Not unwary!
Sam

Sent tomorrow from my time machine

On 22 Apr 2021, at 14:30, SAM JEWELL via groups.io <jewell@...> wrote:

﻿Being a little unwary of computer EMF models/calculators for ICNIRP, I have been doing some measurements on my 23cm EME system, using a calibrated portable spectrum analyser and an antenna with a known antenna factor. The results have been interesting and do actually bear out some of the calculated numbers.
I felt that I would be happier knowing actual W/m2 levels at points of public access near my premises, on the bands above 1GHz, rather than relying completely on calculated values in a highly complex environment, where vegetation, fences and relative access height are all factors that affect the real levels.

73 de Sam, G4DDK

On 22 Apr 2021, at 14:06, Roger Ray via groups.io <g8cub@...> wrote:

﻿I suggested before a simple pir to turn off the tx, if someone is standing in front of the dish. You would not be communicating then anyway.
Seems like a good idea particularly to stop someone looking down the waveguide, while you are sorting another problem.
I am intending to do some real life measurements against icnirp levels with a Narda s3 personal monitor, especially for the bands above 10GHz. As it will be near field the calculator is not a lot of use, even if it worked above 10G.
Roger
G8CUB

On 22 Apr 2021, at 10:08, Dave via groups.io <davidnewman55@...> wrote:

﻿Thanks Andy,
Great. That makes it all seem a lot easier.
73
Dave G4GLT.

On 22 Apr 2021, at 09:59, Andy G4JNT <andy.g4jnt@...> wrote:

﻿
Just don't transmit with anyone standing in front of the dish - and if you feel you must, write down that that would be the case.   No need to rope off
You wouldn't have anyone standing there for 6 minutes while you're working anyway, would you.

Andy

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

typical

militaryoperator

Tuesday, copying the IOW beacon on 23 at S2, today its S6/7 but there's no one on.

A few on KST but obviously not watching their screens!

Ben.

Re: EMF Calculator

SAM JEWELL

Being a little unwary of computer EMF models/calculators for ICNIRP, I have been doing some measurements on my 23cm EME system, using a calibrated portable spectrum analyser and an antenna with a known antenna factor. The results have been interesting and do actually bear out some of the calculated numbers.
I felt that I would be happier knowing actual W/m2 levels at points of public access near my premises, on the bands above 1GHz, rather than relying completely on calculated values in a highly complex environment, where vegetation, fences and relative access height are all factors that affect the real levels.

73 de Sam, G4DDK

On 22 Apr 2021, at 14:06, Roger Ray via groups.io <g8cub@...> wrote:

﻿I suggested before a simple pir to turn off the tx, if someone is standing in front of the dish. You would not be communicating then anyway.
Seems like a good idea particularly to stop someone looking down the waveguide, while you are sorting another problem.
I am intending to do some real life measurements against icnirp levels with a Narda s3 personal monitor, especially for the bands above 10GHz. As it will be near field the calculator is not a lot of use, even if it worked above 10G.
Roger
G8CUB

On 22 Apr 2021, at 10:08, Dave via groups.io <davidnewman55@...> wrote:

﻿Thanks Andy,
Great. That makes it all seem a lot easier.
73
Dave G4GLT.

On 22 Apr 2021, at 09:59, Andy G4JNT <andy.g4jnt@...> wrote:

﻿
Just don't transmit with anyone standing in front of the dish - and if you feel you must, write down that that would be the case.   No need to rope off
You wouldn't have anyone standing there for 6 minutes while you're working anyway, would you.

Andy

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

Re: EMF Calculator

Roger Ray

I suggested before a simple pir to turn off the tx, if someone is standing in front of the dish. You would not be communicating then anyway.
Seems like a good idea particularly to stop someone looking down the waveguide, while you are sorting another problem.
I am intending to do some real life measurements against icnirp levels with a Narda s3 personal monitor, especially for the bands above 10GHz. As it will be near field the calculator is not a lot of use, even if it worked above 10G.
Roger
G8CUB

On 22 Apr 2021, at 10:08, Dave via groups.io <davidnewman55@...> wrote:

﻿Thanks Andy,
Great. That makes it all seem a lot easier.
73
Dave G4GLT.

On 22 Apr 2021, at 09:59, Andy G4JNT <andy.g4jnt@...> wrote:

﻿
Just don't transmit with anyone standing in front of the dish - and if you feel you must, write down that that would be the case.   No need to rope off
You wouldn't have anyone standing there for 6 minutes while you're working anyway, would you.

Andy

On Thu, 22 Apr 2021 at 09:52, Dave via groups.io <davidnewman55=icloud.com@groups.io> wrote:

Hello,
I have done my calculation for 10ghz portable using 5 watts and a 48cm dish with waveguide feed.
I hadn’t realised just how good waveguide is as regards losses are concerned. My duty cycle is quite low.
The separation distance given at the end is 1.8 metres. I presume that the only reliable way of achieving this is to
rope off a radius of 1.8m in the favoured directions. Any comments?
73,
Dave G4GLT

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