Geekzone: technology news, blogs, forums
Guest
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.



403 posts

Ultimate Geek


Topic # 84377 29-May-2011 21:28 Send private message

Can anyone recommend a cost effective outdoor (roof mount) FM aerial for radio?

Create new topic
1544 posts

Uber Geek
+1 received by user: 55


  Reply # 475654 30-May-2011 08:42 Send private message

I use a short piece of wire on the end of a length of coax tied to the TV pole with a bit of string. Works fine and cost nothing as I had heaps of ocax in the junk box.

484 posts

Ultimate Geek
+1 received by user: 2


  Reply # 475656 30-May-2011 08:46 Send private message

Still got your old VHF TV aerial? Connect that to your radio, most times is more than adequate.

880 posts

Ultimate Geek
+1 received by user: 21

Trusted

  Reply # 475847 30-May-2011 18:09 Send private message

I concur with illicit - our combo VHF/UHF aerial picks FM up with no problem.



403 posts

Ultimate Geek


  Reply # 475891 30-May-2011 19:22 Send private message

illicit: Still got your old VHF TV aerial? Connect that to your radio, most times is more than adequate.


mm1352000: I concur with illicit - our combo VHF/UHF aerial picks FM up with no problem.


Does this not need some kind of filter? Does it need to be at a 45 degree angle? (I have a feeling I've asked these question before...)

I do have a VHF aerial, and it's in really good nick. 

If the VHF fails, I'll try the wire idea.

EDIT: ah yes, it seems I've repeated my own thread: http://www.geekzone.co.nz/forums.asp?ForumId=34&TopicId=76670

So the VHF at 45 degrees then. I'll try it tomorrow. 

880 posts

Ultimate Geek
+1 received by user: 21

Trusted

  Reply # 475905 30-May-2011 19:46 Send private message

Interesting - never knew about the 45deg thing. Our aerial is pretty much vertical as its purpose is to pick up DVB-T and analog TV signals. It looks like this...although it may not even have that many short pieces. The FM + analog TV + DVB-T is amplified, then combined with satellite signals by a multiswitch, then split 8 ways and 4 ways again on one of the 8 way feeds. All modes work fine. Smile

5971 posts

Uber Geek
+1 received by user: 109

Trusted
Subscriber

  Reply # 475916 30-May-2011 20:01 Send private message

Technically mainline FM transmitters use slant polarisation this means they work well with a mixed receive antenna, ie does not matter if H or V there is only a 3db penalty unless slanted 90deg out.

So as others have said a BandI/III TV antenna will typically do a good job.

Oh and if you do go for slanting your antenna when standing behind the antenna right side down.

Cyril

11136 posts

Uber Geek
+1 received by user: 557

Trusted
Subscriber

  Reply # 476035 30-May-2011 23:42 Send private message

VHF antennas work OK so long as they are pointing the right way for FM, but watch out as most amps have an FM trap in them as it us usually way stronger so overload things, so as a result with the trap, they are attenuating the FM not amplifying it.

I got the biggest that there was and it was cheap as, as I wanted to see if I could get one of the LPFM stations. It worked, for about 2 weeks before some bloody ethnic mob started up 0.2 away and overmodulating.




Richard rich.ms

1544 posts

Uber Geek
+1 received by user: 55


  Reply # 476082 31-May-2011 09:07 Send private message

mm1352000: .Our aerial is pretty much vertical as its purpose is to pick up DVB-T and analog TV signals. It looks like this...although it may not even have that many short pieces. Smile


If its the same as in the picture then no its not. Its two horizontall polarised antennae stacked one above the other.
If rotated 90 degrees it would be two vertically polarised antennae side by side.

16 posts

Geek


  Reply # 476107 31-May-2011 09:53 Send private message

Most of the Large Transmitting sites are using Circular Polarisation, so rotation of the antenna will not make too much difference.. 
Some are Vertical, but I havent seen any Slant for a while.. There were some in the 80's so they could well still be around.

On the fringe it's definitely worth trying all options of polarisation even with circular as its not often perfect in all directions and objects in the path can reduce one component more than the other.
I've always wanted to try making a circular receiving array with H and V antennas 90° combined for deep fringe testing..

My experience is mostly with Skytower Akl where the large FM1 array is circular and the FM2 is vertical. Within a few kms it can be useful to use a horizontal antenna to reduce the FM2 signals which are quite hot on the ground from the less directional small array..

11136 posts

Uber Geek
+1 received by user: 557

Trusted
Subscriber

  Reply # 476380 31-May-2011 20:35 Send private message

which ones are on fm2?




Richard rich.ms

1 post

Wannabe Geek


  Reply # 479968 11-Jun-2011 04:49 Send private message

if you have an exising vhf tv aerial buy a wallplate with fm/vhf splitter - most radios have a 75ohm coax aerial plug - just connect to the fm outlet of the wallplate - easy

296 posts

Ultimate Geek
+1 received by user: 24

Trusted
Chorus NZ

  Reply # 480063 11-Jun-2011 15:09 Send private message

richms: which ones are on fm2?


Hi techricky, yes which ones are on fm2?

Create new topic




Twitter »
Follow us to receive Twitter updates when new discussions are posted in our forums:



Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:



Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:





Trending now »

Hot discussions in our forums right now:

Snap refuses to replace faulty gear
Created by Brendan, last reply by sorceror on 26-Oct-2014 21:19 (33 replies)
Pages... 2 3


House Auctions
Created by t0ny, last reply by Geektastic on 26-Oct-2014 22:31 (71 replies)
Pages... 3 4 5


Speed limit when overtaking? Teach me please.
Created by nakedmolerat, last reply by Hobchild on 26-Oct-2014 00:11 (92 replies)
Pages... 5 6 7


VDSL, which router/modem sub $200?
Created by TeaLeaf, last reply by NonprayingMantis on 25-Oct-2014 19:48 (28 replies)
Pages... 2


Neon - Sky's new streaming service
Created by JarrodM, last reply by JimmyH on 25-Oct-2014 17:37 (29 replies)
Pages... 2


Snap have failed our company!
Created by dafman, last reply by kornflake on 23-Oct-2014 17:41 (37 replies)
Pages... 2 3


Thief taunts 12 year old via stolen laptop
Created by macuser, last reply by charsleysa on 22-Oct-2014 23:49 (12 replies)

iPad Air 2 and iPad Mini 3. Gonna get one?
Created by Dingbatt, last reply by dickytim on 26-Oct-2014 12:32 (116 replies)
Pages... 6 7 8



Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.

Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.