[cma-l] AM v FM

[Tony Bailey]

Another source, the one I used to compile the AM propagation spread 
sheets is the BBC publication by H E Farrow Long & Medium Wave 
Propagation (1958).  This gives an insight into ground conductivity and 
signal strength measurement.  There are free copies available online, 
however, if anyone needs a copy I can email a decent set of scanned 
pages, it's about 5 Mbyte in total.

Tony Bailey

On 20/12/15 16:36, Two Lochs Radio wrote:
> Appreciated, though there must be some comfort in the fact that the 
> design has been 'standard issue' for a century, and is used by many of 
> the most powerful AM transmitters such as Drotiwich. You might also 
> find BS1386 of some interest.
> The most critical aspects seem to be as you'd expect getting a good 
> earth place below the capacity hat, and getting a high quality tuning 
> coil with very low resistance and able to handle the relatively 
> high voltages involved (but for a transmitter of a 100W or so that's 
> not so tough).
> The client needs 'expectations management', I guess. If you find the 
> theoretical antenna design would in all likliehood cut the 
> client's electricity bill to a quarter, he might be willing to accept 
> a little uncertainty in the exact radiation performance! If you could 
> take the antenna efficiency up from 8% to say 30-40%, there's a very 
> big saving in runnings costs to be had.
> Alex
>
>     ----- Original Message -----
>     *From:* Ian Hickling <mailto:transplanfm at hotmail.com>
>     *To:* The Community Media Association Discussion List
>     <mailto:cma-l at mailman.commedia.org.uk>
>     *Sent:* Sunday, December 20, 2015 1:24 PM
>     *Subject:* [cma-l] AM v FM
>
>     I appreciate all the advice and input - thank you.
>     I have the huge advantage of having worked in an engineering
>     laboratory that built VHF and UHF antennas and range-tested them
>     so I am very fortunate to have an inbuilt comprehension of how
>     they look and perform.
>     Nowhere in all that worthy information is there evidence of energy
>     propagation patterns - actually measured in the field as opposed
>     to calculated or computer modelled.
>     Most important - the difference between success and failure.
>     I can't guarantee to a Client how well an AM (MF) antenna will
>     perform as I can with FM (VHF) - and that worries me.
>
>     *Ian Hickling*
>     Partner
>
>     <http://www.transplanuk.com/>
>     /Office: 01635 578435  (7am-11pm UK time)/
>     /Carphone: 07530 980115 (only responds when driving)/
>     /6 Horn Street, Compton, NEWBURY, RG20 6QS/
>
>
>
> _______________________________________________
>
> Reply - cma-l at commedia.org.uk
>
> The cma-l mailing list is a members' service provided by the Community Media Association - http://www.commedia.org.uk
> Twitter: http://twitter.com/community_media
> http://www.facebook.com/CommunityMediaAssociation
> Canstream Internet Radio & Video: http://www.canstream.co.uk/
> _______________________________________________
>
> Mailing list guidelines: http://www.commedia.org.uk/about/cma-email-lists/email-list-guidelines/
> _______________________________________________
>
> To unsubscribe or manage your CMA-L mailing list subscription please visit:
> http://mailman.commedia.org.uk/mailman/listinfo/cma-l


-- 
Local Reports at http://www.ravensound.pilgrimsound.co.uk

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.commedia.org.uk/pipermail/cma-l/attachments/20151221/ba0e1ff2/attachment.html>