Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old February 7th 05, 07:04 PM
Richard Clark
 
Posts: n/a
Default

On Wed, 09 Feb 2005 17:52:37 GMT, "John" wrote:
Can someone tell me please an easy way to calculate the optimum angle of
radiation from a transmitting antenna over a given path on the HF bands
(160m - 10m)?


Hi John

Use a propagation modeler and tailor the antenna characteristics to
observe the results.

73's
Richard Clark, KB7QHC
  #2   Report Post  
Old February 9th 05, 06:52 PM
John
 
Posts: n/a
Default Angle of Radiation

Can someone tell me please an easy way to calculate the optimum angle of
radiation from a transmitting antenna over a given path on the HF bands
(160m - 10m)?

OK, I guess its all to do with the height of the reflective layer in play
and the distance of the QSO but I'd really appreciate some clues as to how
to work this out.

Thanks

John



  #3   Report Post  
Old February 9th 05, 07:37 PM
Caveat Lector
 
Posts: n/a
Default

Maybe check ON4UN's book -- "Low Band DXing"
He has info on this
Too lengthy to quote here

--
Caveat Lector (Reader Beware)
Help The New Hams
Someone Helped You
Or did You Forget That ?



"John" wrote in message
...
Can someone tell me please an easy way to calculate the optimum angle of
radiation from a transmitting antenna over a given path on the HF bands
(160m - 10m)?

OK, I guess its all to do with the height of the reflective layer in play
and the distance of the QSO but I'd really appreciate some clues as to how
to work this out.

Thanks

John





  #4   Report Post  
Old February 9th 05, 08:35 PM
Roy Lewallen
 
Posts: n/a
Default

Get W6ELProp - it's easy to use, and free. http://www.qsl.net/w6elprop/.

Roy Lewallen, W7EL

John wrote:
Can someone tell me please an easy way to calculate the optimum angle of
radiation from a transmitting antenna over a given path on the HF bands
(160m - 10m)?

OK, I guess its all to do with the height of the reflective layer in play
and the distance of the QSO but I'd really appreciate some clues as to how
to work this out.

Thanks

John



  #5   Report Post  
Old February 9th 05, 09:35 PM
Reg Edwards
 
Posts: n/a
Default

The elevation angle of a radio wave is not related to antenna construction.

It is calculated by trigonometry and is geometrically related to the
distance between two points on the Earth's surface, the height of the
ionospheric reflecting layers involved, and the number of hops.

If a radio wave leaves the Earth at one end of the path and returns to Earth
at the other end, then the elevation angles of the path taken are the same
at both ends. And the same in the other direction. (To forestall
nitpickers let it be said things can vary around averages.)

The optimum angle at which to point a radio antenna, either for transmit or
receive, is obviously the same as the elevation angle of the radio path.

BUT NO AMOUNT OF WAVING THE ANTENNA ABOUT WILL AFFECT THE ELEVATION ANGLE OF
THE RADIO PATH.

For given points on the Earth's surface, height of reflecting layer, and
number of hops, the angle of elevation of the radio path is fixed.

The angle at which the radiation from an antenna is a maximum is an entirely
different matter.

Calculation of a path elevation angle on a curved Earth not very difficult
but is a little too complicated to be written here.

Up to 1500 groundpath miles the Earth can be considered to be flat. Trig
calculation is then schoolkids stuff.

Full formulae can be found in maths books under "Spherical Trigonometry" or
in practical radio engineering books.

Calculations can be interesting but are invariably roughly approximate
because layer height involves guesswork. And by the time you've finished a
calculation the height has shifted. Or the number of hops has changed from 2
to 3. The only things which remain static are your own latitude and
longitude.

To calculate propagation statistics of one and two hop radio paths,
including elevation angles, download simple program TWOHOPS in a few seconds
from website below and run immediately.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........




  #6   Report Post  
Old February 10th 05, 12:46 AM
W9DMK
 
Posts: n/a
Default

On Wed, 9 Feb 2005 20:35:14 +0000 (UTC), "Reg Edwards"
wrote:

The elevation angle of a radio wave is not related to antenna construction.

It is calculated by trigonometry and is geometrically related to the
distance between two points on the Earth's surface, the height of the
ionospheric reflecting layers involved, and the number of hops.

If a radio wave leaves the Earth at one end of the path and returns to Earth
at the other end, then the elevation angles of the path taken are the same
at both ends. And the same in the other direction. (To forestall
nitpickers let it be said things can vary around averages.)

The optimum angle at which to point a radio antenna, either for transmit or
receive, is obviously the same as the elevation angle of the radio path.

BUT NO AMOUNT OF WAVING THE ANTENNA ABOUT WILL AFFECT THE ELEVATION ANGLE OF
THE RADIO PATH.

For given points on the Earth's surface, height of reflecting layer, and
number of hops, the angle of elevation of the radio path is fixed.

The angle at which the radiation from an antenna is a maximum is an entirely
different matter.

Calculation of a path elevation angle on a curved Earth not very difficult
but is a little too complicated to be written here.

Up to 1500 groundpath miles the Earth can be considered to be flat. Trig
calculation is then schoolkids stuff.

Full formulae can be found in maths books under "Spherical Trigonometry" or
in practical radio engineering books.

Calculations can be interesting but are invariably roughly approximate
because layer height involves guesswork. And by the time you've finished a
calculation the height has shifted. Or the number of hops has changed from 2
to 3. The only things which remain static are your own latitude and
longitude.

To calculate propagation statistics of one and two hop radio paths,
including elevation angles, download simple program TWOHOPS in a few seconds
from website below and run immediately.


The original poster, John, had already indicated the answer to his own
question - but Reg was the only one who recognized that and had the
correct follow up. Congrats, Reg.


Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html

  #7   Report Post  
Old February 10th 05, 05:33 AM
Cecil Moore
 
Posts: n/a
Default

John wrote:
Can someone tell me please an easy way to calculate the optimum angle of
radiation from a transmitting antenna over a given path on the HF bands
(160m - 10m)?

OK, I guess its all to do with the height of the reflective layer in play
and the distance of the QSO but I'd really appreciate some clues as to how
to work this out.


Try the propagation chapter in the ARRL Antenna Book.
--
73, Cecil http://www.qsl.net/w5dxp


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---
  #8   Report Post  
Old February 10th 05, 10:42 AM
Ian White G3SEK
 
Posts: n/a
Default

Cecil Moore wrote:
John wrote:
Can someone tell me please an easy way to calculate the optimum angle
of radiation from a transmitting antenna over a given path on the HF
bands (160m - 10m)?
OK, I guess its all to do with the height of the reflective layer in
play and the distance of the QSO but I'd really appreciate some clues
to how to work this out.


Try the propagation chapter in the ARRL Antenna Book.


That would be a very good introduction to modern software like W6ELPROP.
What it teaches you is that angles of arrival vary considerably, even
for one given path, for reasons ranging from time of day to time in the
11/22-year sunspot cycle.

Remember that the F-layer is constantly changing height, especially if
it's around around dawn and dusk at one of the reflection points. This
means that at certain times the propagation has to 'flip' from say
3-hop-F to 4-hop-F, so the angle will flip too. And don't forget the
E-layer, if that's there too.

W6ELPROP will actually tell you what propagation modes are the most
likely at various times of day... and the reality is *much* more
complicated than the simple pictures shown in older books.

The ARRL Antenna Book does rather assume that you can put up any antenna
you can dream of; in which case, it will help you design the optimum
system. Ideally, the antenna needs to be able to adapt to the needs of
the moment.

But for most of us, it's much simpler than that. We can never achieve
the low angles that are sometimes needed for some of the most important
paths, so it simply comes down to doing the best we can. "Adaptability"
comes down to possibly having a second-choice antenna... which at
certain times may turn out to be better.

But even if we can't actually *do* anything about it, it's better at
least to understand that arrival angles (or conversely, optimum launch
angles) are actually very variable.



--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
  #9   Report Post  
Old February 10th 05, 11:37 AM
Mike Coombes
 
Posts: n/a
Default

Looking at the ARRL Antenna book it seems that the angle of radiation is
pretty well fixed on the type of antenna.
"Ian White G3SEK" wrote in message
...
Cecil Moore wrote:
John wrote:
Can someone tell me please an easy way to calculate the optimum angle of
radiation from a transmitting antenna over a given path on the HF bands
(160m - 10m)?
OK, I guess its all to do with the height of the reflective layer in
play and the distance of the QSO but I'd really appreciate some clues to
how to work this out.


Try the propagation chapter in the ARRL Antenna Book.


That would be a very good introduction to modern software like W6ELPROP.
What it teaches you is that angles of arrival vary considerably, even for
one given path, for reasons ranging from time of day to time in the
11/22-year sunspot cycle.

Remember that the F-layer is constantly changing height, especially if
it's around around dawn and dusk at one of the reflection points. This
means that at certain times the propagation has to 'flip' from say 3-hop-F
to 4-hop-F, so the angle will flip too. And don't forget the E-layer, if
that's there too.

W6ELPROP will actually tell you what propagation modes are the most likely
at various times of day... and the reality is *much* more complicated than
the simple pictures shown in older books.

The ARRL Antenna Book does rather assume that you can put up any antenna
you can dream of; in which case, it will help you design the optimum
system. Ideally, the antenna needs to be able to adapt to the needs of the
moment.

But for most of us, it's much simpler than that. We can never achieve the
low angles that are sometimes needed for some of the most important paths,
so it simply comes down to doing the best we can. "Adaptability" comes
down to possibly having a second-choice antenna... which at certain times
may turn out to be better.

But even if we can't actually *do* anything about it, it's better at least
to understand that arrival angles (or conversely, optimum launch angles)
are actually very variable.



--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek



  #10   Report Post  
Old February 10th 05, 12:25 PM
Ian White G3SEK
 
Posts: n/a
Default

Mike Coombes wrote:
Looking at the ARRL Antenna book it seems that the angle of radiation
is pretty well fixed on the type of antenna.


Talking about "the" angle (as if there was only one) is misleading
ourselves.

Every antenna has a *range* of angles over which it radiates (or
receives) the best. The aim is to make that coincide with the *range* of
angles over which signals are likely to arrive.

This is made very clear in the 18th edition of the Antenna Handbook
onwards. It presents arrival angles as a statistical range of
probabilities, over a spread of possible propagation conditions.

If you have only one antenna, then obviously you try to make its very
best radiation angle coincide with the most *likely* angle of arrival.
But it's a game of chance. Occasionally the angle may be very different
from the most likely value, so you have to accept that you're going to
be some dB down... or dead in the water. And that is where having a
choice of different antennas really scores.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Radiation angle vs turns count in a coil W4JLE Antenna 9 December 20th 04 10:35 PM
Electromagnetic radiation Mike Terry Shortwave 0 August 24th 04 10:23 PM
Serious radiation questin [email protected] Antenna 45 August 22nd 04 11:42 PM
The Apollo Hoax FAQ darla General 0 July 22nd 04 12:14 PM
Cardiod radiation pattern - 70 cm phased vertical dipoles Ray Gaschk Antenna 3 February 21st 04 01:26 AM


All times are GMT +1. The time now is 12:42 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017