View Single Post
  #65   Report Post  
Old December 28th 08, 09:35 AM posted to rec.radio.shortwave,rec.radio.amateur.antenna
John Smith John Smith is offline
external usenet poster
 
First recorded activity by RadioBanter: Nov 2006
Posts: 2,915
Default Antenna for shortwave reception

RHF wrote:

...
Yeah - Once it is 'placed' in the "System" the MatchBox
becomes part of the "System" and becomes one of the
loses within the "System"
...


Actually, the ONLY reason to use a matchbox is that the antenna is less
than optimal for the freq(s) in question, end-of-story. However,
multi-band operation and simply having to cover a wide swath of
frequencies makes this the logical way to go, a matchbox ... in an ideal
situation, a matchbox would be avoided.


Now -if- That is True : Then Why Us The MatchBox
within an RF Energy Radiating System ?


There is nothing magical about a transmitting antenna, like I stated
earlier, the exact same physics govern that antenna in receive or xmit
modes. The matchbox allows you to achieve "maximum POOR performance"
from the POOR antenna ...

...
So you are say that a MatchBox will not improve
the ERP of an RF Energy Radiating System ?
And that the Receiving Station will not hear you
'better' when the MatchBox is properly used with
the RF Energy Radiating System ?
...


I said NO such thing, indeed, I stated the EXACT opposite, it allows
maximum power transfer to the antenna, however, the losses in the POOR
antenna are now increased due to the losses in the matchbox--as heat.
And, no problems which exist in the POOR antenna have been rectified,
they are just masked ...

...
Electrical Characteristics = 'apparent electrical length'
...


As I stated before, physical length need not be related to electrical
length, however, in the most efficient design possible, they WILL be ...
and that is only considering maximum transfer of power to the antenna,
not, necessarily, the ether--and, that is NOT necessarily related to a
desirable pattern of radiation of that power from the POOR antenna--the
patten, IMHO, is governed, mainly, by antenna length and shape, however,
some designs actually can cheat this, at least a bit.

- And, this is all-in-a-nut shell;

- as you realize, a proper education
- in this field is NOT a trivial thing.
...


being an old timer myself - i still find simply listening
to the radio to be enjoyable ~ RHF
.
.


As I stated before, a complete explanation/understanding of all factors
involved defies a simple explanation ... as, if that were possible, no
one would spend years in college, they could attend a week or a month
and come away an expert.

And, my field is computer science, this is all just a hobby with me.
The little knowledge which I have assembled has been done over the
course of years, even decades. I am hear to find out just "how deep
this rabbit hole goes ..."

Regards,
JS