Which kind of aerial in Whitby.

Forums › Freeview (DVB-T/DVB-S) › Which kind of aerial in Whitby.

wodger

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#141340 9-Mar-2014 15:11

Hi,

I have this aerial at the moment. It used to be combined with a VHF aerial and in the 7-8 years we have been here, it has never worked. Yesterday I took it down, threw away the VHF aerial, and wired the UHF aerial straight to the TV, pointing it in various directions and seeing what happened. To my delight it worked, though the signal strength and quality were low. I put it back up, and pointed it at Kaukau:

I used Google Maps and made a custom map to draw a line so I would know where to point it - there is a big hill in the way, so I've never been completely sure what direction Kaukau is from here.

The result has been good - although this example is pretty bad. The bit error level was in the low hundreds earlier today, and quality and signal strength were both in the teens, which resulted in a watchable picture and the best numbers I got all day after moving it around a bit. Pointing it at kaukau when I actually knew where kaukau was and putting it on the roof made a big difference:

SO, my questions are:

1. Should I angle it up the hill, even just a little? The radio waves I'm picking up aren't coming through the hill, so are they bending and coming down/around the hill and would my aerial therefore pick them up better if angled up, or to the right slightly to meet them? Or am I better to leave it pointing straight at kaukau? Maybe someone has a signal strength meter I could borrow?

2. I will invest in a new aerial - I am under the impression the one I have is not a good choice for where I live. I've seen info suggesting Phased array and was about to get one of those, but then I saw something suggesting a long x-type:

So, this:

vs this:

Also, I presume the higher up I can get it, the better? Any advice appreciated.

Cheers
Julian.

sbiddle

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#1001763 9-Mar-2014 16:30

Pointing it in the direction of Kaukau may not always be the best option. UHF does tend to bounce around a lot, and a reflection may infact offer better signal quality.

ajw

1932 posts

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#1001774 9-Mar-2014 17:03

How about just getting a aerial tech to give you a free quote and some free advise. Also input your address here to see what coverage could be available.

http://www.freeviewnz.tv/coverage.aspx

sbiddle

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#1001777 9-Mar-2014 17:15

Whitby is a nightmare for coverage. The online coverage checker isn't the most reliable tool.

ajw

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#1001778 9-Mar-2014 17:18

I note there is also a UHF transmitter on Baxters knob.

https://maps.google.co.nz/maps?q=-41.12697+,+174.86225

Behodar

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#1001782 9-Mar-2014 17:31

There's a map of all transmitters available if that helps.

spearsniper

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#1001813 9-Mar-2014 18:30

Unless you live in the boonies, just check out what all of your neighbors are using, and where their aerial are pointed. Check out the orientation of them as well as the direction.

richms

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#1001827 9-Mar-2014 18:57

It looks like a band 3 VHF antenna, not a UHF one you have pictured so prettymuch any UHF one should work a tonne better than it is now.

Richard rich.ms

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sbiddle

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#1001850 9-Mar-2014 19:45

spearsniper: Unless you live in the boonies, just check out what all of your neighbors are using, and where their aerial are pointed. Check out the orientation of them as well as the direction.

This isn't always the best approach either. Lots of installers are relying on reflections these days, something you simply couldn't do in the analogue world as you'd suffer from massive amounts of ghosting.

There are at least 3 or 4 houses in my street with aerials facing anywhere from 90 to 180 degrees different to mine. Copying them isn't always a good idea as the reception from a reflection can be specific to the exact location and the type of aerial.

dwl

371 posts

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#1001868 9-Mar-2014 20:10

richms: It looks like a band 3 VHF antenna, not a UHF one you have pictured so prettymuch any UHF one should work a tonne better than it is now.

I agree. A Band 3 antenna has directors (the bars at the front) which are much longer than those for UHF and can act as reflectors, bouncing the UHF signal away. A UHF antenna should do better.

[Edit] To answer questions:

1) The vertical beam width of a low gain UHF antenna is quite broad but if going with a high gain (either type shown) you might notice a slight difference pointing at the ridge line if the hill is high. The signal is coming from diffraction over the hill although the best bearing can vary if the hill is sloped - you might get a bit more if less vertical diffraction angle at a slightly different horizontal bearing. However, this only applies with high gain UHF and if yours is Band 3 the gain is probably so low (or negative) that all bets are off. The peak (low) gain can be coming from strange angles off the centre line.

2) If you can borrow a medium gain (low cost) UHF antenna you might find it gives a good result. Both types shown could work well but the retail prices can get excessively high for what you are getting and these larger antennas are also more vulnerable in the wind.

Your tuning frequency shows you have Kaukau rather than Baxters Knob which is in a similar direction. You might get Baxters (TVWorks will show 570 MHz rather than 562 MHz) but with the hill in the way the higher power of Kaukau may win out.

As mentioned above, the signals can bounce around when you are not line of sight. The best starting point is still probably at the ridge on the Kaukau bearing but if that doesn't give an adequate result pan around.

The house coax can be another cause of signal loss. What worked at VHF might have excessive loss at UHF as possibly never cabled with cable that is low loss at UHF and/or a long run. Any splitters will also reduce signal level.

As you have some signal with the existing antenna it seems not too bad and a UHF antenna would be a good start (assuming I have read the photo correctly and it is VHF Band 3).

Brunzy

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#1001878 9-Mar-2014 20:19

sbiddle:
spearsniper: Unless you live in the boonies, just check out what all of your neighbors are using, and where their aerial are pointed. Check out the orientation of them as well as the direction.

This isn't always the best approach either. Lots of installers are relying on reflections these days, something you simply couldn't do in the analogue world as you'd suffer from massive amounts of ghosting.

There are at least 3 or 4 houses in my street with aerials facing anywhere from 90 to 180 degrees different to mine. Copying them isn't always a good idea as the reception from a reflection can be specific to the exact location and the type of aerial.

Did you install them Steve?

B1GGLZ

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#1001886 9-Mar-2014 21:02

richms: It looks like a band 3 VHF antenna, not a UHF one you have pictured so prettymuch any UHF one should work a tonne better than it is now.

+1.
That's a high band VHF antenna, not UHF so won't work very well on Freeview.

Apsattv

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#1001950 10-Mar-2014 00:14

Hard to see not a very good photo , but it looks like a VHF tv antenna. Probably zero gain on UHF or negative gain on UHF! Go with the phased array and you should have plenty of signal. Be it reflected or direct.