Help Understanding EMR

[VK2AVR]

Can you be grumpy without being old, or old without being grumpy, or not a man and be grumpy, or old, or both old and grumpy? May be a better discussion point than the present one!

needs more venn diagram

Geoff, I was only reflecting a statement that has been made by others on several different threads, so sensible people like you could knock it on the head by quoting the offical documentation. As have said else where, and as Luke points out here, ground-mounted antennas are going to need a level 2 assessment because they are "accessible to the public" (whatever that might mean).

Fair enough, just be wary of perpetuating something you know is wrong lest a) somebody attribute it to being your opinion, as I did, and b) that it acts as Colin's bush lawyer example that the more people saying a certain thing the more widely believed it becomes. I know you said "I have read" but the implication is that if you repeat it without caveats then you also agree with it.

The marconi vertical is an interesting one, because of the grey statement "accessible to the general public". It is a little frustrating that this is not well defined, but the other way of looking at this situation is rather than nutting out every tiny detail in legalspeak, we just apply some common sense to the situation to ensure that others aren't injured by our antennas and there is safe separation for reasonable public behaviour. As long as there are no injuries, we don't really need draconian rules and the restrictions they inevitably come with. Would you like it specified that any ground mounted vertical had to be enclosed by a 1.8 metre wooden fence and locked gate, stepped back from the antenna by 5-10 metres in all directions? Gee, wouldn't that be hard to fit in the average backyard. So let's not push too hard for clarification, it can work against you too

[VK5TM]

Just to throw in an extra bit of confusion re - "accessible to the general public" definition.

In one document, it states that the householder, including the ham operator, is considered general public (I have to go and find the relevant quote, but that appears to be accepted amongst most here).

Yet, in another document, RPS3, it states that an amateur radio operator is considered an 'aware person'.

From RPS3_qa.pdf

AN EXPLANATORY QUESTION & ANSWER GUIDE TO A R P N S A
AUSTRALIAN RADIATION PROTECTION AND NUCLEAR SAFETY AGENCY.
THE ARPANSA RADIATION PROTECTION STANDARD FOR MAXIMUM EXPOSURE LEVELS TO RADIOFREQUENCY FIELDS — 3 KHZ TO 300 GHZ

Aware user
A person who is appropriately trained to use two-way radios and other portable
wireless devices (see Schedule 5, clause S5.2) which expose the user to levels likely to
exceed the basic restrictions for general public exposure. Appropriate training includes
awareness of the potential for exposure and measures that can be taken to control that
exposure. Persons in the aware user group may include, but are not limited to, the
following categories:
(a) Emergency service personnel.
(b) Amateur radio operators.
(c) Voluntary civil defence personnel.

Another set of contradictions to confuse the issue.

[VK3HJ]

Owen, my Bobtail Curtain array is for the 40 m band, so radiators are approximately 10 m (vertical) and the phasing sections are approximately 20 m each side (joining the top ends of the three radiators).
There seems to be some concern that an antenna that does not comply with Level 1 is somehow dangerous, mysterious, or illegal.
Simply stated, Level 1 is where the antenna is of no concern, as at the level of a person on the ground near the antenna, the RF fields are considered safe. Level 2 is where the antenna may radiate a possibly hazardous level of RF out to a known distance, at the height of a person standing on the ground, and this is the area we should not have people present. This is readily calculated, and in most instances won't be more than 2 or 3 metres from the antenna.

Richard, my horses have gone grey, and I have gone bald, but I somehow doubt EMR has anything to do with that!

73,
Luke VK3HJ

[VK2OMD]

Luke,

Owen, my Bobtail Curtain array is for the 40 m band, so radiators are approximately 10 m (vertical) and the phasing sections are approximately 20 m each side (joining the top ends of the three radiators).

Ok, you will note that below 10MHz you must measure or calculate BOTH E field and H field time averaged, and exclude the general public from the space where EITHER exceeds the level set out in RPS3 Table 7.

The worst case distances for E field and H field from the antenna conductors might be several metres, conduit (you mentioned) is unlikely to be an adequate exclusion due to the distances required.

There seems to be some concern that an antenna that does not comply with Level 1 is somehow dangerous, mysterious, or illegal.

Yes, drama whipped up by purveyors of FUD (Fear, Uncertainty and Doubt), people who can not or will not read and fairly interpret the documents.

Unfortunately, the WIA broadcast last Sunday gave widespread distribution to yet more FUD.

Go back to the source documents for reliable information. If you accept any of my advice, this is the most valuable!

Simply stated, Level 1 is where the antenna is of no concern, as at the level of a person on the ground near the antenna, the RF fields are considered safe. Level 2 is where the antenna may radiate a possibly hazardous level of RF out to a known distance, at the height of a person standing on the ground, and this is the area we should not have people present. This is readily calculated, and in most instances won't be more than 2 or 3 metres from the antenna.

Quite, Level 1 critera represent a low risk scenario and no further assessment is required.

Everything else is Level 2 criteria and requires a detailed assessment. The outcome of the assessment at some given power level, modulation etc gives the space from which "members of the general public" (as defined in the relevant documents) must be excluded by some means.

Owen