Julian,
No apologies necessary, there's absolutely nothing wrong with asking questions.
As far as research goes, I'm not aware of what studies have been done. This is probably because it has been of little concern to me based on what I know about RF and the design of Yagi-Uda antennas.
RF is non-ionizing meaning it is incapable of causing any changes at a molecular level. RF only has the ability to cause heating of objects in its vicinity. That said, I'm not sure it's even possible to feed an arrow with enough power to cause any real heating without damaging the antenna first.
We can look at why antennas like this are used in the first place. These antennas have a good front to back ratio that directs the RF away from the handle. If we compare the radiation pattern of an arrow to that of a standard rubber duck antenna you'll see that much less energy is directed at the user. Personally, if I was concerned with exposure I would worry more about a 1/4 wave whip than a Yagi. Of course that assumes I don't have the Yagi pointed at myself. :)
If you would like more on the topic this page may be a good starting point https://www.fcc.gov/engineering-technology/electromagnetic-compatibility-div...
Others in the group may know of studies done on the subject, I'm sure they'll share if they do.
73,
Mike Diehl AI6GS
On Aug 14, 2017, at 11:40 PM, Julian Horn (Clara) [email protected] wrote:
Apologies if this is a dumb question, but it is from a relative newcomer to this field . . . :) Has any research been carried out on the (medical) safety of hand-held antennas such as the Arrow whilst transmitting? I understand the power is relatively low, but unlike say a mobile (cell) phone, average power I imagine will be much higher? Are there any measurements of field strength this close to the driven element and any assessments of the risks?
73, Julian M0NUX
On 15 Aug 2017, at 01:14, Mike Diehl [email protected] wrote:
On a more serious note there are advantages to hand holding the Arrow even if it feels like you need to be an octopus to pull it off. There's a certain hand ear coordination that seems to come naturally when matching polarity by simply twisting your wrist. This advantage alone can be significant over fixed polarity or polarity matching by some mechanical means. The only time I would recommend a tripod is if there is some physical reason for not being able to hold it.
Often times people go the tripod route because it seems like too many things are going on at once. One common pitfall is trying to log while a pass is in progress, usually on paper. A better solution is to record the audio for playback later. A simple voice recorder or even a smartphone works great. If using a voice recorder be sure to set the clock to UTC, timestamps will make logging a lot easier.
Another way to free up a hand is to use a boom mic headset with a foot switch for PTT. By doing this you free up your hand to operate the VFO(s).
Like Bryan pointed out, it can seem counterintuitive that holding the antenna can make things easier but when you evaluate the rest of your station you may find other ways to free yourself to aim.
If you find that there's just simply no way to operate without a tripod then maybe you can describe the difficulties you face. I've seen many clever designs, each with their own advantages and disadvantages making them each suitable to a different crowd. Let us know what you're looking to get out of a tripod setup, I'm sure there are plenty of people willing to share their solutions.
73,
Mike Diehl AI6GS
On Aug 14, 2017, at 4:33 PM, Bryan KL7CN [email protected] wrote:
Mike's being funny. :)
I used to use a $10 tripod I got from the Goodwill. The main thing I appreciated about it was its ability to do axial rotation -- think: camera on its side. When the Arrow was attached, I would us that feature to rotate the Arrow along its axis.
Nowadays I do what Mike does: I hold the Arrow in my hand. It takes some time to become comfortable with holding the antenna correctly while adjusting for Doppler and pressing the mic button, but after some practice I found it to be the most efficient way. It's counterintuitive, but using your hand to orient the antenna is very fast and flexible.
-- bag
Bryan KL7CN/W6 Location: CM98, usually E-Mail: [email protected] Telephone/SMS: 408-836-7279
On Aug 14, 2017, at 16:23, Mike Diehl [email protected] wrote:
I find a biped to work best with an arrow antenna. Works great for aiming and polarity matching.
73,
Mike Diehl AI6GS
On Aug 14, 2017, at 1:55 PM, Laura Tunnell [email protected] wrote:
What is best tripod for the arrow II handheld antenna ?
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Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb