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Which antenna?

 
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Which antenna?
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trioxide
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Post Which antenna? Reply with quote
I know there is a lot of documentation here regarding antenna types and construction and kudos to Marko for a fantastic site but I have some questions :

a) How do you select the best antenna for the job? I currently have a PVC slim-jim style antenna that I built which has low SWR and seems to work beautifully, but I want to try something else, just to compare. Should I build a 'comet' style with radials, or a copper J-pole or should I build a dipole? I really just want a good omni - so which is the best?

b) Length and spacing determines the resonant frequency of an antenna, what determines the power handling capability?

Thanks,
Trioxide
Wed Feb 14, 2007 2:26 am View user's profile Send private message
pcs
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Post Reply with quote
Your antenna is pretty good and hard to beat without going to multi-bay dipoles
or directional antennas.

Anything else you go to will almost certainly perform worse.

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Thu Feb 15, 2007 10:30 pm View user's profile Send private message Visit poster's website
magicfm
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Post Reply with quote
Hello trioxide!!!

My opinion is :

the best antennas for low power ~100W is two half vawe dipoles! They are working the best of all, if you corectly install them!!! In my case there is no SWR at all!
Two months ago i had this 15W transmiter from PCS..... so with theese two half vawe dipoles, good coverage (with stereo, and RDS) was till 15km!!! My tallest radio listener was 50 km far from me... at good weather for transmitting (-25 degrees C .... but the FCC cath us two months ago Applause , but its ok.. it seems that after ~2 weeks my new transmiter wil be ready , at this time il be more smater!

Here is picture, but its no so correct, if you will be interesed i will calculate your sizes!

http://freefm.lv/lv/photogallery.php?photo_id=109

magic fm 92.0 Mhz Latvia
Thu Feb 15, 2007 11:07 pm View user's profile Send private message Visit poster's website
pcs
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Post Reply with quote
Looks great

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Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Thu Feb 15, 2007 11:27 pm View user's profile Send private message Visit poster's website
trioxide
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Post Reply with quote
Hi Magic FM,

That diagram and image looks awesome. I'd be interested in building one of these. Could someone spent a bit of time translating that construction diagram? I can make sense of parts of it (being able to read Polish helps) but some of it is a little confusing. Anyway, thanks for the replies and thanks in advance for anyone who does translate the details,

Trioxide

magicfm wrote:
Hello trioxide!!!

My opinion is :

the best antennas for low power ~100W is two half vawe dipoles! They are working the best of all, if you corectly install them!!! In my case there is no SWR at all!
Two months ago i had this 15W transmiter from PCS..... so with theese two half vawe dipoles, good coverage (with stereo, and RDS) was till 15km!!! My tallest radio listener was 50 km far from me... at good weather for transmitting (-25 degrees C .... but the FCC cath us two months ago Applause , but its ok.. it seems that after ~2 weeks my new transmiter wil be ready , at this time il be more smater!



magic fm 92.0 Mhz Latvia

Fri Feb 16, 2007 6:17 am View user's profile Send private message
whiplash
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Post Reply with quote
Magicfm that it sweet! Applause
I hope you don't mind but I would also be intersted in an explanation of the diagram. My frequency is 102.9.
Thanks in advance

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Fri Feb 16, 2007 1:28 pm View user's profile Send private message
whiplash
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Post Reply with quote
Thanks so much for explaining it!
Just another quick question,
Can I make the dipoles myself or would i be better off to order from PCS?
My transmitting power will be approx 15W. As I said in my previous post I was using a desert slim jim and getting about 8km on half power so this antenna with full power should be awesome!
I Had a look at the picture and can understand you however if at all possible could you show a close up of where the cable joins onto the dipole.
Thanks again!

By the way your english is actually pretty good! Don't apologise!

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Sat Feb 17, 2007 2:41 am View user's profile Send private message
whiplash
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Post Reply with quote
Once again thankyou very much!
I'll give it a go one of these days, all i gotta do is find a nice big TV antenna mast! 10 metres high should do the trick!
I got some RG 213 (20 Metres) and this stuff is expensive! Now I've just gotta find some heavy 75ohm cable. Not much around here in australia but I'll try!
I'll let you know how I get on!

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Check our site: http://thepotato.com.au/
Sat Feb 17, 2007 11:56 am View user's profile Send private message
pcs
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Post Reply with quote
Just a short note:

MagicFM has been using this forum to promote his own to a large extend,
but I could live with that since he provided usefull info. But later he started
bad-mouthing our products and this took the matter way too far.

Imagine you have a party. One of the guests keeps telling everyone there's
another party across the street. Later at some point he starts telling everyone
how the beer is really bad here and how the food stinks.

What do you do?

Exactly, and that's what I did, too.

Last thing I need is some guy from Latvia telling me there is no low pass filter
even though I know very well there is one, after all I designed the damn
thing myself, duh. This really pissed me off.

_________________
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Wed Feb 21, 2007 12:02 pm View user's profile Send private message Visit poster's website
whiplash
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Post Reply with quote
Hey Mark,
Good job!
He was making some harsh comments about me over at his website so that kind of turned me off a bit
Fortunately I'll have enough money saved up soon to be able to buy an antenna from you guys
I would have got one sooner however Our studio computer decided to cark it so I had to buy a new one!

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98.7 & 102.9 Whiplash FM
The Freshest Hits More Often
Check our site: http://thepotato.com.au/
Thu Feb 22, 2007 1:53 am View user's profile Send private message
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