[Lowfer] 472-479 kHz

[craig wasson]

Well - we can agree to disagree then.   My point is there may be some
advantage to intentionally using a less efficient antenna if it gives
you lower losses beyond the antenna.  It's just something I don't
think people ever look at except for receiving - where losses don't
matter much anway.  Given the reversability of paths - maybe what
makes a good RX antenna would make a good TX antenna if the efficiency
was not a big factor.   Obviously within reason.

Energy that is measured for ERP would exclude that which went into
heating the antenna, loading coil, etc.  Maybe even local ground
losses depending on how far away you measure ERP.  Once those photons
fly off the antenna then they will land somewhere.  So my point is
those losses don't matter if the goal is to net out at some fixed ERP
(photons per second) limit.

For a 1 megawatt commercial/military station a 3db increase in antenna
efficiency might be cheaper than another megawatt.  But for us - going
from 10w to 100w to compensate for 10db in antenna losses is not such
a big deal.

I've been experimenting with "small" (like in 50') loops on 1750M.  My
problem is the wire in the loops is too small so I burn up way too
much energy in the resistance of the loop.  Going to multiple loops or
zigzags like some cellular loop antennas use did not help because the
resistance of the longer wire cancels out the efficiency gains.

My QTH is in a forest and vertical antennas couple too much energy to
the trees, so I have not given up on the tx loop idea.

Craig - N6IO


On 9/25/12, Douglas D. Williams <kb4oer at gmail.com> wrote:

> Hi Craig. You are absolutely correct. Once the RF energy leaves the
> antenna, it has to go somewhere. The problem is, most of the RF energy
> input into an inefficient antenna is simply lost as heat.  JD and others
> please correct me if I am wrong.
>
...
>
> Our military (and all military users of VLF/LF all over the
> globe), take great pains to make their VLF/LF transmitting antennas as
> efficient as possible, given the restrictions of their budgets, which are
> vastly superior to all of ours put together, by a factor of (who
> knows?....more than Bill Gates is worth) or more.
>
>>
>