I'm a RF novice, no problem admitting it. I want to receive terrestrial HD digital in Opunake.
The Taranaki transmitter is right around the other side of lit'l old Mount Taranaki.
No likelihood of extending HD broadcast in the foreseeable future to places like Opunake (yes I know I can get satellite, and "upscale" to 1080i but that's a subject for another forum question - see elsewhere).
I could point a 91 element (or large triple folding) aerial at say Wanganui (I suspect too many hills in line of path), or possible Nelson (would need to have a more accurate idea of the direction of transmission for both transmitters there) or possible something in Wellington (pointing to Kapiti?) BUT I'm pretty sure neither aerials alone would do it.
So, fellow readers, is the distance just "impossible" (like sound the RF power quarters proportional to the distance from the source (have I got that right?))?
Would I need to "gang" 2 or 3 high gain aerials to pull in a usuable HD signal?
If so does anyone know of a suitable "diplexer" ("triplexer"?) that would combine the signals?
Has anyone experimented similarly or knows technically why such experiment would be doomed to failure?
Appreciate your comments.
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Your best bet would be Mt KauKau
Wanganui and Kapiti are too low in altitude and very low powered .
But as its a sea path it will be very unreliable , but good experimentation.
I do the same in reverse watch Mt Egmont DVBT signal can vary 20db
in an hour Tide , temp , air pressure all change signal level .
Try a low noise mast head amp such as the Kingray MDA20U ( low noise figure and diecast shielded box.) model
Antenna try a Phased Array such as the german made WISI ( stewarts powerbase ) should be able to supply
UHF long distance reception is theoretically possible under ideal conditions. In the Amateur Radio world it's ocasionally possible to work Australian Amateur stations at 430mhz in Summer given the right conditions in the Tasman Sea. A frontal system lying from Brisbane to Auckland usually provides good propogation so a frontal system lying Nelson to New Plymouth might be good. Looking at your location (and depending on your height above sea level) one of the Nelson transmitters or Mt Kaukau in Wellington should be possible but not all the time. You'd probably need to gang several high gain aerials together and use a masthead amp. Worth experimenting with if you have no obstructions in the way. I would think Wanganui would be near impossible and Palmerston North just may be possible but a lot of terrain in the way. Signal propogation across water is much better.
I'd suggest start experimenting with a high gain aerial such as you suggest and a masthead amp. Add more aerials if no results. If you get to four aerials in a bay and no results them maybe give up. Be prepared to watch a lot of blank screen while experimenting.
Try google for some info on antenna stacking. Not easy to find info but try here to start.
The Nelson transmitters barely make it to Kapiti I suspect the transmit array does not point this direction so Taranaki would be worse . Wharite would be tricky due to rising ground mid way
I have my VHF AUS DVBT receiver high gain band 3 Antenna and Mast Head amp ready for next lot of tropo . Have had a flash of pic from the Seven Network about two weeks ago same as time amateur radio opening on 144 Mhz !!
Thanks for sage comments.
So Kapiti looking at Mt Taranaki works? Does that result in a reliable signal i.e. receiving consistent HD transmission without significant loss of picture? If so, what no. of antennae do you use (3?)?
The links to yagi construction were useful; I haven't seen anything yet more germain to my specific question.
More inclined to experiment if I had my hands on 2-3 old 91 element UHF antenna….. will try house wreckers.
Haven't looked at the masthead amp yet but correct me if I am wrong, I just can't run coax from each antenna, connect on parallel and hey presto! Or is this situation not the same as putting a uhf and vhf analogue antennae together (ah the old days!).
Hoping my question might draw in some transmission engineers but I guess they might be doing something sensible like playing pool or fishing.
Really appreciate your replies guys - thanks.
You have plenty of options, Wharite, Wanganui, Kapiti, Kaukau, Mount Campbell
Call your local installer they would surely know who locally is getting signal if any and from where.
I recall people in Taranaki watching Nelson Mainland tv when it was running on via Analogue site Takaka Hill
Try Google - antenna array phasing harness.
Interesting stuff for intrerconnecting antennae.
First to NZDTV . No Wang and Kapiti are too low in altitude . This is not the flat earth society here , plus they only produce a few watts power . Wharite direction has too many obstructions and Mt Campbell barely makes here and its LOS I suspect its off the side of the main TX lobe . Digital is a different to analog any fade produces no pic unlike analog where it just goes snowy . Best bet would be Mt KauKau I would expect you might RX it % 10 of the time
Egmont from here can be 40db of fading esp this time of year Winter is a lot more stable but still drops out
so no its not reliable but was a good experiment ( 94 element antenna was no better than the WISI phased array
Right Steve but they could get a bounce or deflected signal off one of those hills that is more reliable than the long over water path via Kaukau.
But really the 1st option is to contact a local installer in the region they would have first hand experience. It will be interesting to hear what happens as the project progresses.
Maybe the poster could also contact Mainland tv in Nelson as to North Island reception of their digital service.
Im sure Garry would be keen to discuss it http://www.7-media.net/mainland/
Looking at his location I don't see a Hill bounce being a real option .
A local installer would prob look at coverage map and say NO , satellite only .
I know that's what I would say If I was the installer . Its bad enough doing a job
in good coverage area with all the nonsense that goes on !! Doing a job like that would be just asking for trouble !!
A google pin showing the posters exact location would be a start.
Well yes Steve it depends on how much money they want to throw at the problem. I'm sure 8 of these phased together might get a little bit of signal :D
The issue is its NOT line of site to any transmitter and due to distance there will be long periods of NO signal good old earth curvature
so even a huge array wont provide %100 reception .
But it was an Experimentation idea for self install
Property is Fox Street Opunake, essentially a stones throw from Opunake Beach entrance.
The discussion has been interesting, many thanks.
I have seen only one uhf antenna and its pointing northward, possibly receiving the previous TV3 analogue signal?
There are no specific installers for this small town but the lack of terrestrial antenna (and only sat dishes) speaks volumes. Even in New Plymouth local installers shake their heads at certain areas of the city - but again the amateur succeeds despite this! OK, not always..
If I get some cheap antennas suitable to create a reasonable array then I'll start experimenting.
Til then, standard def sat reception viewing. Just another aspect of living in the distant colonies … (but the surf waves are not often crowded, I can kite-fish on an expansive beach without seeing another person today, and a traffic jam is being stuck at the same lights twice!)