AirNav Systems Forum
AirNav RadarBox and RadarBox24.com => AirNav RadarBox and RadarBox24.com Discussion => Topic started by: sasa1000 on May 12, 2010, 08:44:13 PM
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Just wondering if anyone could advise me on the best option re my Radar-Rama antenna. It is in the attic just now connected with Westflex etc, all the right cabling, and as you can see by my polar diagram there is room for improvement. My house is approx 10m above sea level and height to roof peak is approx 25-27 ft. i have a hill line to the se of me which is approx 132m high, this summit is prob 0.5 km away. NW of house hills peak about 103m and are about 1.5 km away and the rest of the hills are fairly distant and lower. My question is, would I gain much by putting Radar-Rama outside (prob gain another 6 ft in height) or would it be better to go down amplifier route or even try supplied antenna in attic. Please accept my grovelling apologies for such a long winded post.
Sandy
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looks like your range is okay(ish) with current setup as sw shows this. Other directions could simple be down to those hills.
Putting the ariel as high as possible will "always" help, it can never be too high.
Also how long have you ran the system to develop the polar, as over time some of the gaps will/may get filled as aircraft pass through them. Other thing to look at is flight routes, polar will only show where its picked up local hardware aircraft flying, if nothing flies for example to your east then polar will never extend that direction.
i'd reconnect first get the ariel outside and high.
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Hi Dave, thanks for your reply. I have had the box running 24/7 with the Radar-Rama antenna since Fri 30 April, so coming up for 2 weeks now. I never expected to get very far east due to the close proximity of the hills but I was hoping for a bit better coverage elsewhere. This I know is due to the geography of the isles and is not the fault of the RB, as I am really impressed with the coverage down to north of Scotland.
Just want to try and make sure the gains from mounting outside will be worth the effort (and grief from wife) before I do it.
Sandy
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Sandy - I'm sure DaveG is right - the general maxim is "height is might", and pre-amps should come a long way down your list of priorities. We've had several reports that pre-amps can cause a LOSS of signals because of the noise they can generate.
Rod
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Hi Sandy, I'm sure you'll find you get vastly better results by siting antenna outside. Personally, I'd say only go for a pre-amp to overcome long co-ax downlead run losse. If you can site RB in loft with active USB lead extender - may better than pre-amp.
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Thanks for that Rod, I would hate to buy a pre-amp and find out it did no good. Incidentally I would probably attach an earth wire to the mast if mounting outside, so would mounting it to mast suffice or is it better to actually attach it to antenna?
Sandy
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Once again Jon, thanks for the advice. I think I will rule out the pre-amp and go for outside option (just annoying I had a mast up a few years ago and took it down) I have 10m Westflex on antenna just now, mostly coiled up till I get final site & length required, along with this I have 2 active USB extenders as I intend trying to get them down behind the plasterboard when antenna is permanently sited.
Sandy
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The antenna to mast clamp will act as the connection , but a lead from antenna to mast to earthing would be belts and braces, and could dissipate static better as weather will cause some corrosion and higher resistance.
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Will start looking in to this at the weekend, was wondering about telescopic masts as I have seen lightweight ones on the net that clamp to the house, anyone know if these are any use? Just that I may be able to gain a few more fett with one of these.
Sandy
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As for belts & braces Jon, it may be an idea to go down that route as it is certainly a cheaper option that cooking the RB.
Sandy
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Hi Sandy, rather than a lightweight telescopic, I'd suggest you go for an aluminium scaffold pole, still comparatively light, but much sturdier and a bit more expensive than the standard TV poles, standard length of 20 feet.
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Are the scaffold poles not too heavy then Jon? I had given them some consideration but thought they would need a few clamps to secure them to the house. Not sure if I will go down the telescopic route yet, will probably end up with mast about 10 ft and aim for 6 ft above roof line.
Sandy
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Hi Sandy, aluminium scaffold poles are a heck of a lot lighter than galv. steel, they don't bend and are the standard outer diameter
http://www.scaffoldingsupplies.co.uk/products/details/1872.html
You can get s/s fittings (or car exhaust type clamps if you're a cheapskate!) to secure them to a wall, a local welder would be able to make up stand off brackets, you'd be able to get about 10 feet above roof ridge if you've got a gable end to use. It depends how close/vulnerable you are to salty air and strong winds.
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Going to look in to this at the weekend Jon, only problem is the wind as we do take quite a battering. One of the highest recorded broke the recorder at the RAF early warning station at speed of just over 200 mph (also blew the radar domes away) Our usual round about the house would be gale to severe gale.
Sandy
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.......only problem is the wind as we do take quite a battering.
That's the one reason why I still have my antenna mounted in the loft. We also get winds >100mph, and most people around here avoid anything mounted externally. It's worth moving the antenna around in the loft - sometimes you can get much better coverage just by moving it to a different position.
For info, here's my coverage from the loft.
(http://farm4.static.flickr.com/3337/4605455715_a342f90023_m.jpg) (http://www.flickr.com/photos/tarbat/4605455715/sizes/o/)
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Just had a quick look in MemoryMap, and if I've guessed your location correctly, I can see why you would have poor reception to the SE, looking at the land profile:
(http://farm2.static.flickr.com/1276/4606138666_ec06a10ea3_m.jpg) (http://www.flickr.com/photos/tarbat/4606138666/sizes/o/)
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Are the scaffold poles not too heavy then Jon? I had given them some consideration but thought they would need a few clamps to secure them to the house. Not sure if I will go down the telescopic route yet, will probably end up with mast about 10 ft and aim for 6 ft above roof line.
Sandy
Have a look at the attached pic of my gable end mounting, Sandy. This is a ten footer with the the aerial about 6ft above the apex - much as you seem to think would suit.
Beyond the radarmax you will see a discone and also out of shot are a couple of stack mounted TV aerials. I am exposed to the southwest and while we don't get Tarbat's weather here (thank God!) we still get a decent blow from time to time. I reckon the discone has more wind-resistance than the 1090 aerial yet this has stood safely for 15 years.
Another advantage to this gable end mounting is that the coax feeds immediately into the attic/loft of the house and thence directly to the box. ie. precious little coax needed.
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Hi Sandy, with a 20' al. scaffold pole, you'd be fine with 9' above ridge, top bracket about 2' down and bottom bracket at the bottom(!). The wall thickness is some 4mm, so no real movement with a <1m 1090 antenna, whereas a lighter gauge tube would give out vibrate and deteriorate.
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Thanks once again for all the info and photos guys. Your help & advice is invaluable. I would be going the same way as bratters I think as I have an overflow pipe 4 ft below apex of roof where I would feed co-ax through as we no longer have storage tank in attic. I was up the ladder tonight looking for previous holes but unable to find them. I will be phoning a lad tomorrow for price for mast + brackets also price for him to fix as my ladder is just a bit too short.
Sandy
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I'm thinking to use short mast supplied with Radar-Rama ant and clamp it to new mast as the antenna is a tight fit on top of supplied short mast. I would also gain another couple of feet this way. Can't wait to get this done as hopefully my coverage will be a lot better.
Will the Radar-Rama receive better signals just by being outside?
Sandy
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Will the Radar-Rama receive better signals just by being outside?
Sandy
Obviously if it's not enclosed by brickwork, it will be better. Stick it out of the window and it will be better. But if the antenna is not up in the air it won't be good.
Remember, it's line of sight so if the aerial can't "see" it, you won't get it.
Height, height and height again.
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That figures I suppose, never had a chance to get mast today as working all day, just got internet connected at 11.40 pm after hub crashed earlier in the evening. Guess if I can get above roofline of neighbours house I am heading in the right direction.
Sandy
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Thanks for the informative posts. I have a 45ft tree in the front garden that is causing a "shadow". The top of my gable is only 13ft so I am looking at all options.
(Wife did not take to kindly to the suggestion to cut the tree down)
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I think one element of the question is the direction of the tree vis a vis the house and whether it blocks a particularly important line of sight.
We don't know your home position and therefore your most potentially fruitful directions. You need to take into account your own particular interests - a specific airport for instance - and also consider the more distant topography before concluding that the tree is a major or a minor pain.
It could be that beyond the tree lies nothing much of interest - empty oceans or maybe a range of hills that would preclude good signals anyway. Having said that, siting your antenna as far back from the tree as possible will reduce its "shadow" and you may also have the freedom to angle the antenna to work "round" the tree.
I have a friend nearby in a bungalow whose discone is atop a mast running up the rear of the house. It's a very neat and tidy job which, being a bungalow, he was able to secure without the help of contractors/erectors. It clears the roofs of adjacent two storey houses comfortably.
You may like to point out to her indoors that a tree of 45 feet is undoubtedly a threat to the foundations of your buildings and should be immediately trimmed before subsidence sets in.
Bonzais are nice too.