EMF Calculation - No Inverted V

Dom - 2E0WHQ

Following on from this evening's excellent presentation by Den, I thought I'd have a look at the latest RSGB EMF calculator (version 11), which can be downloaded from here:
https://rsgb.org/main/technical/emc/emf-exposure/

Unfortunately, I appear to have fallen at the first hurdle as one of my main antennas is my 20m Inverted V, for which there is no predefined template. The PAEC-1 tables only cover 40m to 160m, so I'm a little stumped. The apex of the inverted V is about 8m and the ends are about 2m from the ground. I guess I could calculate it as a horizontal dipole at 2m, but that would give a ridiculous and inaccurate near field zone calculation.

Looks like I've broken the theory already.

Dom, 2E0WHQ

Den (M0ACM)

Hi Dom.

Though I haven't done the calc run, I can confirm that there is AS YET no PAC for the 20m dipole/inv V.

I will have a look when I wake up properly.... nodded off watching a film till my phone went bing !

Two initial thoughts come to mind...

1. I am pretty sure that a PAC will appear in due time for a whole variety of "typical" aerial set ups. JAV and Co really are working hard on their modelling activities and PACs seem to be a priority with them as I read between the lines. I think they went for the low bands initially as a proof of concept to Ofcom in an area where, as some would see it, Ofcom are struggling to articulate the Guidance. That accepted they are now free to replicate this concept to other bands and setups.

2. Assessing at 20 metres is not a current priority. We have until next spring to complete docs for frequencies from 10 to 110 MHz, so my humble suggestion at present would be to do 144MHz and up and leave HF for a while and see what emerges to assist.

Hope that helps.

...and thanks for your feedback on this evening. It was a challenge to pack something as 'involved' and critical to us all into a Talk evening without racing at such a pace as to leave everyone MORE confused than they were when they came in!

73

Den

Dom - 2E0WHQ

Thanks Den,

I was just trying to get ahead of the game by checking my HF antennas. I'm fine with my current 2m/70cm Colinear setup, mainly due to my Diamond V2000 antenna being 5.5m up on a scaffold pole half way down the garden. Curiously though, the calculator won't allow me to use the same Colinear antenna for 6m. It asks me to 'use different antenna'. The V2000 is a tri-band Colinear covering 70cm, 2m and 6m, but the calculator won't allow you to use a Colinear for 6m.

If I continue with the Colinear, it says I'm compliant based on height, as does the calculation if I use a Vertical Dipole as the 6m antenna.

Whilst the calculator is good, it's clear that there are still quite a few issues with it. I'm sure they'll get ironed out over time.

73

Dom.

Den (M0ACM)

Noted the V2000 anomaly at 50megs.
I will add it the list of issues noted.

You are absolutely right, the V2000 should do 6 (and 10 ?).

I think the achilles heel of the whole calc situation is going to be the behind the scenes data used to set up the aerial gain data.

It might be well worth downloading the Thilo Kootz model and checking both 2m and 6m for the V2000 with his calc as I am pretty certain HIS tables will include that collinear on 6.

If the 2m figs tie up with rsgb/ofcom, I think you would be well safe accepting his 6m results too (with a suitable note to that effect in your explanation record.

73

-------- Original message --------
From: "Den (M0ACM) via groups.io" <denf.acm@...>
Date: 22/10/2021 1:09 am (GMT+00:00)
To: sdarc@groups.io
Subject: Re: [sdarc] EMF Calculation - No Inverted V #EMF

Hi Dom.

Though I haven't done the calc run, I can confirm that there is AS YET no PAC for the 20m dipole/inv V.

I will have a look when I wake up properly.... nodded off watching a film till my phone went bing !

Two initial thoughts come to mind...

1. I am pretty sure that a PAC will appear in due time for a whole variety of "typical" aerial set ups. JAV and Co really are working hard on their modelling activities and PACs seem to be a priority with them as I read between the lines. I think they went for the low bands initially as a proof of concept to Ofcom in an area where, as some would see it, Ofcom are struggling to articulate the Guidance. That accepted they are now free to replicate this concept to other bands and setups.

2. Assessing at 20 metres is not a current priority. We have until next spring to complete docs for frequencies from 10 to 110 MHz, so my humble suggestion at present would be to do 144MHz and up and leave HF for a while and see what emerges to assist.

Hope that helps.

...and thanks for your feedback on this evening. It was a challenge to pack something as 'involved' and critical to us all into a Talk evening without racing at such a pace as to leave everyone MORE confused than they were when they came in!

73

Den

James (M1DST)

As I said last night Den, I thoroughly enjoyed the topic.  Thanks again for doing all the leg work to make it understandable for the masses.

You indicate you have a list of issues...  Is that an internal list or are you feeding it back to the RSGB?

James

On Fri, 22 Oct 2021 at 09:33, Den (M0ACM) <denf.acm@...> wrote:
Noted the V2000 anomaly at 50megs.
I will add it the list of issues noted.

You are absolutely right, the V2000 should do 6 (and 10 ?).

I think the achilles heel of the whole calc situation is going to be the behind the scenes data used to set up the aerial gain data.

It might be well worth downloading the Thilo Kootz model and checking both 2m and 6m for the V2000 with his calc as I am pretty certain HIS tables will include that collinear on 6.

If the 2m figs tie up with rsgb/ofcom, I think you would be well safe accepting his 6m results too (with a suitable note to that effect in your explanation record.

73

-------- Original message --------
From: "Den (M0ACM) via groups.io" <denf.acm=gmail.com@groups.io>
Date: 22/10/2021 1:09 am (GMT+00:00)
Subject: Re: [sdarc] EMF Calculation - No Inverted V #EMF

Hi Dom.

Though I haven't done the calc run, I can confirm that there is AS YET no PAC for the 20m dipole/inv V.

I will have a look when I wake up properly.... nodded off watching a film till my phone went bing !

Two initial thoughts come to mind...

1. I am pretty sure that a PAC will appear in due time for a whole variety of "typical" aerial set ups. JAV and Co really are working hard on their modelling activities and PACs seem to be a priority with them as I read between the lines. I think they went for the low bands initially as a proof of concept to Ofcom in an area where, as some would see it, Ofcom are struggling to articulate the Guidance. That accepted they are now free to replicate this concept to other bands and setups.

2. Assessing at 20 metres is not a current priority. We have until next spring to complete docs for frequencies from 10 to 110 MHz, so my humble suggestion at present would be to do 144MHz and up and leave HF for a while and see what emerges to assist.

Hope that helps.

...and thanks for your feedback on this evening. It was a challenge to pack something as 'involved' and critical to us all into a Talk evening without racing at such a pace as to leave everyone MORE confused than they were when they came in!

73

Den

Den (M0ACM)

At a suitable point, I will again email John and update him with Members'discoveries.

However since the Pre November deadline is 110 Megs and up, I think he would appreciate resolving any final final data table issues in those bands before moving to infill matters in "Phase 2" - (10-110megs).

Thanks for feedback. Glad the approach 'worked'.

73

-------- Original message --------
From: "James (M1DST)" <james@...>
Date: 22/10/2021 9:38 am (GMT+00:00)
To: sdarc@groups.io
Subject: Re: [sdarc] EMF Calculation - No Inverted V #EMF

As I said last night Den, I thoroughly enjoyed the topic.  Thanks again for doing all the leg work to make it understandable for the masses.

You indicate you have a list of issues...  Is that an internal list or are you feeding it back to the RSGB?

James

On Fri, 22 Oct 2021 at 09:33, Den (M0ACM) <denf.acm@...> wrote:
Noted the V2000 anomaly at 50megs.
I will add it the list of issues noted.

You are absolutely right, the V2000 should do 6 (and 10 ?).

I think the achilles heel of the whole calc situation is going to be the behind the scenes data used to set up the aerial gain data.

It might be well worth downloading the Thilo Kootz model and checking both 2m and 6m for the V2000 with his calc as I am pretty certain HIS tables will include that collinear on 6.

If the 2m figs tie up with rsgb/ofcom, I think you would be well safe accepting his 6m results too (with a suitable note to that effect in your explanation record.

73

-------- Original message --------
From: "Den (M0ACM) via groups.io" <denf.acm=gmail.com@groups.io>
Date: 22/10/2021 1:09 am (GMT+00:00)
Subject: Re: [sdarc] EMF Calculation - No Inverted V #EMF

Hi Dom.

Though I haven't done the calc run, I can confirm that there is AS YET no PAC for the 20m dipole/inv V.

I will have a look when I wake up properly.... nodded off watching a film till my phone went bing !

Two initial thoughts come to mind...

1. I am pretty sure that a PAC will appear in due time for a whole variety of "typical" aerial set ups. JAV and Co really are working hard on their modelling activities and PACs seem to be a priority with them as I read between the lines. I think they went for the low bands initially as a proof of concept to Ofcom in an area where, as some would see it, Ofcom are struggling to articulate the Guidance. That accepted they are now free to replicate this concept to other bands and setups.

2. Assessing at 20 metres is not a current priority. We have until next spring to complete docs for frequencies from 10 to 110 MHz, so my humble suggestion at present would be to do 144MHz and up and leave HF for a while and see what emerges to assist.

Hope that helps.

...and thanks for your feedback on this evening. It was a challenge to pack something as 'involved' and critical to us all into a Talk evening without racing at such a pace as to leave everyone MORE confused than they were when they came in!

73

Den

Den (M0ACM)

Dom,
I have just done a run on the IcnirpCalc and attach results page for 6M for the V2000.
I have assumed some pretty 'standard' condx with 15m of RG213 and an ant height of 5m
Mode FM and 50% TX:RX with 100W from TX
You will see it suggests a "Safety Distance" (EZ) of 1.68m.
144MHz with the same setup advises an EZ of 2.52m
Hope that helps
Den

On Fri, 22 Oct 2021 at 01:50, Dom (2E0WHQ) <domwilko@...> wrote:
Thanks Den,

I was just trying to get ahead of the game by checking my HF antennas. I'm fine with my current 2m/70cm Colinear setup, mainly due to my Diamond V2000 antenna being 5.5m up on a scaffold pole half way down the garden. Curiously though, the calculator won't allow me to use the same Colinear antenna for 6m. It asks me to 'use different antenna'. The V2000 is a tri-band Colinear covering 70cm, 2m and 6m, but the calculator won't allow you to use a Colinear for 6m.

If I continue with the Colinear, it says I'm compliant based on height, as does the calculation if I use a Vertical Dipole as the 6m antenna.

Whilst the calculator is good, it's clear that there are still quite a few issues with it. I'm sure they'll get ironed out over time.

73

Dom.

Den (M0ACM)

Dom,

A final final on this thread (!) I have just delved into the data tables using a recent version (but not 11a) of  the RSGB calc and confirm that "generic" (but not manufacturer/model specific) data is used by the table.

The gain figures used for 2m and 70cm for the "collinear" option are 6.5dBi and 8dBi respectively and the data for 2m, 70cms and 23cms (!)  for the "big collinear" are 8.3dBi, 11dBi and 14.8dBi.

To clarify re the "use different ant" message, the calculator looks at the gain returned from the tables after you choose the antenna.
If the gain comes back as "1", it sees that as not having found a "real" gain figure in the lookup table and pops up the "use different ant" message to advise that any results figures will not be reliable.

Ok, coffee time !

73

Den

On Fri, 22 Oct 2021 at 10:23, Den (M0ACM) via groups.io <denf.acm=gmail.com@groups.io> wrote:
Dom,
I have just done a run on the IcnirpCalc and attach results page for 6M for the V2000.
I have assumed some pretty 'standard' condx with 15m of RG213 and an ant height of 5m
Mode FM and 50% TX:RX with 100W from TX
You will see it suggests a "Safety Distance" (EZ) of 1.68m.
144MHz with the same setup advises an EZ of 2.52m
Hope that helps
Den

On Fri, 22 Oct 2021 at 01:50, Dom (2E0WHQ) <domwilko@...> wrote:
Thanks Den,

I was just trying to get ahead of the game by checking my HF antennas. I'm fine with my current 2m/70cm Colinear setup, mainly due to my Diamond V2000 antenna being 5.5m up on a scaffold pole half way down the garden. Curiously though, the calculator won't allow me to use the same Colinear antenna for 6m. It asks me to 'use different antenna'. The V2000 is a tri-band Colinear covering 70cm, 2m and 6m, but the calculator won't allow you to use a Colinear for 6m.

If I continue with the Colinear, it says I'm compliant based on height, as does the calculation if I use a Vertical Dipole as the 6m antenna.

Whilst the calculator is good, it's clear that there are still quite a few issues with it. I'm sure they'll get ironed out over time.

73

Dom.

Den (M0ACM)

Telling lies again !... THIS is the final final final on this (mis-named!) collinear thread !!...

I've checked the Diamond specs.
The V2000 is advertised with a gain of 2.15dBi on 50 megs.

I have added that to the RSGB table for the "collinear" (since the other two bands' gains match the Diamond specs for 2 and 70) and, in true allegiance  to last night's format, I copy below the appropriate data screen grabs which I trust will zoom up OK when you extract them.
(Just in case: 6m FM 100W 50% TX;RX; 15m of RG213; Collinear, Vertical at 5.5m agl; zero extra attenuation.)

As you see below, the results come back requiring zero horizontal separation and an EZ vertical of 2.7 metres.
Since the base of your ant is at 5.5metres you have 3.7 metres "spare" vertical capacity to go standing on (but not falling offt!) ladders etc!!

Right NOW it's coffee !!

73

Den

On Fri, 22 Oct 2021 at 01:50, Dom (2E0WHQ) <domwilko@...> wrote:
Thanks Den,

I was just trying to get ahead of the game by checking my HF antennas. I'm fine with my current 2m/70cm Colinear setup, mainly due to my Diamond V2000 antenna being 5.5m up on a scaffold pole half way down the garden. Curiously though, the calculator won't allow me to use the same Colinear antenna for 6m. It asks me to 'use different antenna'. The V2000 is a tri-band Colinear covering 70cm, 2m and 6m, but the calculator won't allow you to use a Colinear for 6m.

If I continue with the Colinear, it says I'm compliant based on height, as does the calculation if I use a Vertical Dipole as the 6m antenna.

Whilst the calculator is good, it's clear that there are still quite a few issues with it. I'm sure they'll get ironed out over time.

73

Dom.

Mike (G4HGV)

New version 11b now out that seems to have fixed some of the printing problems

Den (M0ACM)

Thanks Mike.
Would be nice if there were a "subscribe" option so we got push messages! I haven't come across such an option. You?
Den

-------- Original message --------
From: "Mike (G4HGV)" <mleach@...>
Date: 22/10/2021 12:34 pm (GMT+00:00)
To: sdarc@groups.io
Subject: Re: [sdarc] EMF Calculation - No Inverted V

New version 11b now out that seems to have fixed some of the printing problems

Dom - 2E0WHQ

Thanks Den for taking the time to delve a little deeper. If I get a chance over the weekend, I take a look at the finer workings of the spreadsheet to see what data is being pulled from where, etc.
It should be easy enough to plumb in your own figures for custom antennas, etc.

73

Dom

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