YAGI Antenna vs PHASED ARRAY

Forums › Freeview (DVB-T/DVB-S) › YAGI Antenna vs PHASED ARRAY

saintblues

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Geek
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Topic # 242401 26-Oct-2018 17:55

Hi guys,

I have a huge dilemma

Should i install a Yagi point style antenna - something like this https://www.matchmaster.com.au/digital-tv-antennas/02mm-dg91/

Should i install a Phased Array antenna - something like this https://www.matchmaster.com.au/digital-tv-antennas/02mm-mdu36/

Matchmaster's antenna selection guide based on their website says i should be using a phased array and recommends the one ive linked above. The details it gives are as follows:

Frq Signal: 75dBuV, Digital Channels: 27,29,31,33,35,37, Distance: 13.5km, Loss from High Terrain: -1.84dBuV

However, the 3 technicians/installers I've had to site bluntly tell me that phased arrays are garbage. That they have tested them many times and they are crap even in paths where obstacles are in the way of the transmitter. They all recommend a standard small yagi style antenna.

There is a construction site going up literally 25 metres away from my mounting point and they have just installed a phased array. The installers who have come out to site keep telling me its a scheme to make money off people that they are more expensive and installers make more money from them. But their performance is poor. Other houses around the area all have the yagi style.

I am in the Lynfield area and I'm aiming at the Waiatarua transmitter, my place is in a ditch or valley and there is no line of sight to the antenna. Bushes and hills in the way.

Im stuck in 2 minds now. Which style to go for?

Hopefully you guys can help :)

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Ultimate Geek
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Reply # 2114601 26-Oct-2018 18:23

There's a pretty good thread on this already: https://www.geekzone.co.nz/forums.asp?forumid=83&topicid=115157

saintblues

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Reply # 2114622 26-Oct-2018 18:54

One person supports this post

nzkc:

There's a pretty good thread on this already: https://www.geekzone.co.nz/forums.asp?forumid=83&topicid=115157

Hi,

Thanks for that, but is it true that phased arrays are just a big hoax. Like the techs ive met say its performance is poor and its just a lie to make money.

For my particular location and circumstances, I was after peoples thoughts on this and help.

Ill be running about 6-7 TV outlets however I doubt they will all be run at the same time. The distributor module going in the cabinet is the Starview DDM8 as you can see here http://www.dynamix.co.nz/DDM8

Thoughts on this?

RunningMan

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Reply # 2114624 26-Oct-2018 19:00

Go with whatever the installer recommends for your location and distribution requirements. If it doesn't perform as required, then they should remedy it.

mail2mm

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Reply # 2114627 26-Oct-2018 19:07

I would take the advice of the experienced installers. The recommended Yagi has a maximum gain of 16 dB while the phased array maximum gain is 12 dB. The gain specification does not specify a reference, ie, dBi or dBd but since Matchmaster makes both it is probably safe to say the Yagi has 4 dB more gain than the phased array. In an area of challenging reception 4 dB more signal is nice to have.

Neither of these is a small antenna. They both need a solid mount whose location on your roof is determined, at least in part, by a signal survey to determine where the best signal is available.

Ask for high quality RG-6 coax cable (SKY approved cable is one indication) and use compression crimp outdoor F connectors. Put on a weatherproof boot and/or moldable plastic weatherproofing tape like Coax-Seal from Go Wireless NZ.

Good luck. I hope you get good Freeview UHF reception.

mail2mm

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Reply # 2114635 26-Oct-2018 19:24

One person supports this post

A little PS to my earlier message. As RunningMan said the advantage of taking the experienced installers' recommendation is that if it does not work they should remedy it.

If the cabling distance from the antenna to the distribution amplifier location is very far, let's say 15-30 metres, the signal level at the distribution amp input may be insufficient. If so a pre-amplifier at the antenna can help.

I can not say whether a phased array is "rubbish" but the Yagi antenna you referenced has more gain and is a less complicated mechanical design.

alasta

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Reply # 2114672 26-Oct-2018 19:53

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Phased arrays are certainly not rubbish. I have had one for several years and my reception is rock solid.

However I almost have line of sight to Mt Kaukau, so a phased array may not necessarily be suitable for all situations.

clive100

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Reply # 2114696 26-Oct-2018 20:53

Phased Array antennae did perform better in some locations with analogue signal of yesteryear. It was not just about outright signal gain / strength but more about a cleaner signal especially when ghosting occurred due to multiple incoming signals or bad reflected signal due to ground topography & buildings causing leading or trailing ghosting images.

With Digital UHF Freeview its more important to have a clean signal than a stronger one. Although ghosting is not visible with Digital reception an strong unclean signal can cause picture break up & dropout more than a lower strength clean signal might. The Phased Array is more suitable in some areas than a Yagi design due to it's specific characteristics when signal conditions are unstable or affected by various hindrances . Digital signals do not need to be as strong as the old analogue signal but a clean signal is very important.

B1GGLZ

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Reply # 2114708 26-Oct-2018 21:44

Nothing wrong with either type. Just the field patterns are totally different. Yagi has a narrow field pattern while Phased Arrays have a wide field pattern. Whichever one you use depends on location, signal strength and other factors. A Yagi would be much better at extreme range and line of site due to it's narrow field and high gain. Google their antenna field patterns for comparison.

raytaylor

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Reply # 2114741 26-Oct-2018 23:43

I use phased array antennas at microwave frequencies so i dont have much expierence with UHF but I imagine it to be the same principal.

A Yagi antenna is a high gain in a specific direction.

If a tree or object blocks the signal, you can suffer significant loss. Higher gain can sometimes compensate for the loss. But if you are further away from the transmitter, you need more gain.

A phased array antenna uses two smaller antennas side by side.

This gives more physical space for the antenna to 'catch' the signal, but because of their size, they dont make them as big
They are suitable if you are closer to the source, where you dont need the gain, but where a tree could be blocking the signal and when it moves, you want the signal to stay good by catching it in the new position where is passes between the branches.

So imagine a tree trunk / branches / leaves that could be causing you signal issues.

By using a phased array antenna, there is a higher chance it will pick up signals passing through either side of the object.

When the signal is received by both antennas on the phased array, it combines and increases in strength.

So yeah they are not garbage, but just have a specific use case, and that is trees while being closer to the transmitter.

When your further away and have tree issues, it can be better to make your own phased array antenna out of two standard yagi antennas.

Only when the signal is very bad or being split many ways do you add an amplifier.

Ray Taylor
Taylor Broadband (rural hawkes bay)
www.ruralkiwi.com

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SATTV

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Reply # 2114756 27-Oct-2018 08:16

In my previous employ we would use phase array for UHF signals in most locations, yagi have their uses but most of them made for TV are not as good as they could be.

Depending on where you are in Lynfield ( I suspect you are close to Subritzky's old place ) you might be able to point the Antenna to Te Aroha, the downside is Waikato adds.

The other option is Sky Tower.

However in saying that, I would not be keen on doing too much until construction has completed as installing something now might not be good when construction has finished.

John

I know enough to be dangerous

saintblues

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Reply # 2116390 29-Oct-2018 16:50

mail2mm:

A little PS to my earlier message. As RunningMan said the advantage of taking the experienced installers' recommendation is that if it does not work they should remedy it.

If the cabling distance from the antenna to the distribution amplifier location is very far, let's say 15-30 metres, the signal level at the distribution amp input may be insufficient. If so a pre-amplifier at the antenna can help.

I can not say whether a phased array is "rubbish" but the Yagi antenna you referenced has more gain and is a less complicated mechanical design.

I have been quoted between $300 to install the antenna onto the roof. I'd rather install it myself, only thing i don't have is a meter to test the signal while I'm up on the roof.

Cable distance from Antenna to the distribution board is about 20meteres id say possibly more.The cabling from the distribution board has already been run upto the roof using a quality Belden outdoor sky approved RG6 cable.

Only issues is the house is actually in a valley. so there is absolutely no direct line of sight. I'm pretty much up pointing to a hill...

Another issue is how installers love to just say the phased arrays are crap.. so it puts me off buying one. I wouldn't mind installing the phased array and seeing if it does the job. But these installers are so adamant that the phased arrays are simply crap.

saintblues

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Reply # 2116392 29-Oct-2018 16:51

alasta:

Phased arrays are certainly not rubbish. I have had one for several years and my reception is rock solid.

However I almost have line of sight to Mt Kaukau, so a phased array may not necessarily be suitable for all situations.

Thats good to know.

See this is odd because ive been told phased arrays should be used in areas where there is no line of site of where there are obstacles in the way.... who installed your phased array when you have direct line of sight?

saintblues

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Reply # 2116395 29-Oct-2018 16:54

clive100:

Phased Array antennae did perform better in some locations with analogue signal of yesteryear. It was not just about outright signal gain / strength but more about a cleaner signal especially when ghosting occurred due to multiple incoming signals or bad reflected signal due to ground topography & buildings causing leading or trailing ghosting images.

With Digital UHF Freeview its more important to have a clean signal than a stronger one. Although ghosting is not visible with Digital reception an strong unclean signal can cause picture break up & dropout more than a lower strength clean signal might. The Phased Array is more suitable in some areas than a Yagi design due to it's specific characteristics when signal conditions are unstable or affected by various hindrances . Digital signals do not need to be as strong as the old analogue signal but a clean signal is very important.

Thanks for that really helped. See im in a valley where im pretty much pointing to a hill.. when you go up over that hill is when you would possibly achieve some form of line of sight with the Waiatarua transmitter.

So is it just best to just try one or the other? see how it goes. if i have issues install the other one?

alasta

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Reply # 2116399 29-Oct-2018 16:55

saintblues:

alasta:

Phased arrays are certainly not rubbish. I have had one for several years and my reception is rock solid.

However I almost have line of sight to Mt Kaukau, so a phased array may not necessarily be suitable for all situations.

Thats good to know.

See this is odd because ive been told phased arrays should be used in areas where there is no line of site of where there are obstacles in the way.... who installed your phased array when you have direct line of sight?

It was done by the guy in Breaker Bay - I think his name is Lester Goodfellow.

I have line of site to Mt Kaukau from the street but the house is a few metres lower, hence why the antenna almost has line of sight but not quite. Down the hill from me most people seem to have long yagis, so if you're in a valley then that may be better suited to your location.

saintblues

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Reply # 2116400 29-Oct-2018 16:56

B1GGLZ:

Nothing wrong with either type. Just the field patterns are totally different. Yagi has a narrow field pattern while Phased Arrays have a wide field pattern. Whichever one you use depends on location, signal strength and other factors. A Yagi would be much better at extreme range and line of site due to it's narrow field and high gain. Google their antenna field patterns for comparison.

So me being in Lynfield is about 13km from the Waiatarua transmitter. I would say that is considered pretty close. Issue is im in a big valley and my aerial will be pointing pretty much into a hill. im in the heart of auckland so i doubt i would have any issues getting signal. Its more about the quality of the signal since im in the ditch.

And also installers dissing the phased array likes its junk has put me off getting one of them

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