satellite dome or dish antenna

Sorry.. It's not a myth and the proof can be found on any microwave license on file at the FCC. Part of the ERP power calculation is the LOSS of the fiberglass dome on the dish, exactly the same composition found on a DSS dome antenna that is already at rx threshold in a lot of cases. Now add a dome for an extra 1-3db (+ moisture gathered on the surface), and you're asking for trouble. Maybe not today, and maybe not for most people, but it's a well known fact that anything you place in front of any MW antenna: satellite or terrestrial will cause attenuation. There is absolutely no substation for gain, and it's not going to come from that cute little reflector in the domes cannot compared to a Motosat or Winegard.

I swore to never subject myself or my coach to snow, and have been through four heavy snows this year.  The earlier snows were cold and dry snow, so it sort of blew off the dome, but later ones were wet and sticky - had to get up there and sweep the snow off.  Old man, tall slippery coach - I did not have any trouble staying awake up there.

A neighbor has an open dish, on a tripod - the snow just slid off the antenna reflector, and he never lost signal.

Jeff has the attenuation of signal nailed, in my estimation.  I will not repair the dome antenna, should it fail for some reason.  I will opt for an open crank up if I ever replace it. I will spend much time avoiding snow in any case.

Jack Nichols, 2003 Country Coach, KA5IFU

I have no doubt that there's attenuation through the fiberglass, but that wasn't the issue I was addressing; The claim is often made that a dome antenna loses signal in the presence of rain or dew, whereas an open dish does not.

We don't consciously RV in snow, so I don't have a good data point there, but wouldn't expect a good signal. OTOH our kids live above the snow line and regularly lose signal on their open dish.

In my limited experience, an open dish will continue to shed rain or even light snow when it accumulates on a dome. No rocket science - the dish face is pretty much upright (depending on your location, of course) and the rain/dew/snow runs off, whereas the dome is more or less flat across the top and beads of water cling easily. I've had the experience of parking next to friends with a dish and seeing their tv work in light rain while ours was spotty or blank. 

However, our new dome (KVH R4SL) does a much better job in light rain or dew than its predecessor, a KVH SF.  And I'm using Rainex on the dome a couple times a year and it seems to help a bit.  The top of the line KVH has a heater inside to help dispel dew and droplets.

But in heavy weather, none of them are going to work.

SCVJeff said:

Sorry.. It's not a myth and the proof can be found on any microwave license on file at the FCC. Part of the ERP power calculation is the LOSS of the fiberglass dome on the dish, exactly the same composition found on a DSS dome antenna that is already at rx threshold in a lot of cases. Now add a dome for an extra 1-3db (+ moisture gathered on the surface), and you're asking for trouble. Maybe not today, and maybe not for most people, but it's a well known fact that anything you place in front of any MW antenna: satellite or terrestrial will cause attenuation. There is absolutely no substation for gain, and it's not going to come from that cute little reflector in the domes cannot compared to a Motosat or Winegard.

Click to expand...

And as you know the gain of a dish is proportional to the size so the smaller dish in the dome will always suffer from rain fade and the like more than a larger dish.

Tom said:

Oh gosh Bob, you're going to add to the myth busting 

Click to expand...

My dome did experience rain fade before I started using the Dome Magic product, Tom. That's what led me to try it. Once I started using it -- no rain fade. But whether to go with dome or dish is as with most other stuff we decide on -- a matter of trade-offs.

I have experienced the downsides of an open dish, both with Internet (DirecWay, then Hughes, and then Starband) and with crank ups for TV. I now use a Vz air card for internet and a dome for TV. So am able to make the comparison on what works for me very well. The downsides of an open dish, for me, outweigh the good sides. Not sure what HD will do to my own equation, but for now, I am very high on the dome.

As to the snow issue, that would be a non-issue with me. Have been living full time in an RV since the mid 90's and have only been in sticking kinda snow maybe 2 or three times. During those times, it was gone by noon the next day. So I would never include snow in my own decision process on this subject.

BTW, snow "does" stick to an open dish. The attached was taken in Verdi just West of Reno. I was parked at the Boomtown RV park (sadly now a KOA  ). The night before, I used my windshield scraper to remove the snow a couple of times. This image was taken in the later AM so it was beginning to melt off. The night before it was 2 to 3 inches thick.

Aye Bob, I couldn't understand the suggestion that snow does not accumulate on an open dish. Glad you posted that photo. Somewhere around here I have a picture of the kids' dish covered in snow.

Our experience with the dome on our coach is obviously limited; The longest we've stayed out on one trip is 14 weeks, and most trips are closer to a month. But I do know that I'd hear from Chris if/when she couldn't watch TV in bed at night or early morning. We awoke one morning in Las Cruces to unexpected snow, and the King Dome was covered; Definitely lost signal that day (and I heard about it).

I will try to explain the two differences between dome and dish.. One is the dome itself.. if it gets wet then the water will "Get in the way" of the signal and degrade performance (that was easy wasn't it)

now the hard part.

Domes are usually 1/2 of a small dish

Now, Imagine if you will a bunch of parabolic mirrors

you are out at night and you hold the reflector (mirror) up so it gathers light and then use a flat mirror at the focal point to aim light down so you can read a book... System works great but.. There's not enough light to read by.

So you get a larger parabolic reflector and now.. You get more light.

IN fact the larger the reflector..... the more light

(Think of some of those big reflector telescopes... They gater a whole lot of light. from a very small portion of the sky)

Now.. How does this pretain to Sat Television?

Well, that "Dish" is a parabolic reflector and Light, like microwave television signals, is an Electromagnatic radiation..

So.. It is EXACTLY the same thing

The bigger the dish, the more "Gain" it has (That is the more light or in this case television signal, it will gather and focus on the focal point/LNB)

No difference at all between the mirror and the... Mirror.

Thus a DISH will always work better than a dome.. Unless you are moving in which a dome is your only choice.

CANADA/ALASKA question:
The satellites are over the equator. The farther you are from them the weaker their signal (Distance Squared formula if you wish to know) so the farther you are from the equator the STRONGER your antenna needs to be.. So again Dish beats dome


Final comment (I may have posted this before)

Domes see one satellit at a time and that is a KU bird,  DirecTV standard def works great with this kind of system (in fact the Standard DirecTV dish is a single KU antenna)

DishNetwork (SD or HD) and DirecHDTV both need multiple birds.. Some domes can do Dish if you have only one reciever, but none can do DirecHDTV at this time since two of their birds are Ka band

As for snow... I have seen a DISH get snow covered. .I've seen DOMES snow (And Rain) Covered.. Heck I've seen long wire antennas covered with ice and/or snow.  NO antenna is immune to snow or ice

John has it nailed (I taught this stuff for several years).
On another note, I just installed a Trav'ler Friday afternoon past. It is simple, inexpensive (~$1,350 total cost), and worked the first time out of the box. As I noted in another post:
* pookey - the area where it will be
* ~ 10 screws to secure it
* Drill 0.5" hole (I went to the front of the MH thru standard wire channels from Home Depot)
* Run cables and install termination (simple task and, w/antenna install, the only assembly required) on one.
* Pookey and secure cover (provided) over the hole with cables in place ~ 8 screws.
* Connect control box and plug in wall wart; connect TV cable
* Follow simple instructions (includes install reflector- 4 bolts).
* Watch TV less than 4 hrs. after starting.

I'd do this install for $300 (total installed cost at retail ~ $1,650) - not looking for work - I have enough, but I'd be happy to help anyone who has questions. I'm just trying to put some of the prices (as high as $2,400 in one case) I've seen in context.
Ernie

John From Detroit said:

now the hard part.

Domes are usually 1/2 of a small dish

Click to expand...

John, sometimes when I read your posts I feel that if someone asked you for the time, you would give them a lecture on how to build a watch. 

Ned and then Clay mentioned earlier in one sentence each that the size of the dish in a dome is smaller, ergo, less signal. What is "hard" about that?? 

At Newport Beach California (when we had a dome) the morning dew blocked the TV reception for 3 mornings in a row so I had to climb up and dry it off.  It seems to me that dew blocks the  signal quicker and possibly more completely than rain because dew is a much finer, as in small, droplet so it clings more as opposed to larger droplets that may roll off sooner.

Re Canada, with our MotoSat Dish we received good TV signals in the maritime Provinces but after crossing to Newfoundland we only received TV the first night about 90 miles north into  Newfoundland. 

For those going to Alaska on the AlCan Highway you can get TV in the Campground at "Solders Summit" because it's at 4,000 feet altitude.

JerryF

JerArdra said:

At Newport Beach California (when we had a dome) the morning dew blocked the TV reception for 3 mornings in a row so I had to climb up and dry it off.  It seems to me that dew blocks the  signal quicker and possibly more completely than rain because dew is a much finer, as in small, droplet so it clings more as opposed to larger droplets that may roll off sooner.

Click to expand...

Guess you had not tried Dome Magic, Jerry. My understanding of how it works is that it causes the droplets to become rounded on the bottom, so they just roll off vs. remaining flat and able to cling to the surface.

Anyway, it works for me - and with my new bionic hips, climbing the roof just to watch TV is not a good idea anymore (unless it's to watch Kentucky Basketball). From what I am reading here, I may be in trouble when I convert to HD. But that's a ways off for now.

Bob,

I'm sure Dome Magic helps with dew droplets but dew seems not to affect dishes.  It's not fun to climb up on a wet, icy, or snow covered roof.  Also, it's not a very smart thing to do even with "original issue" hips!

Another gripe I had with the dome, in 2003, was that sometimes when you switched to another channel, and I do this often, the dish may have to re-align itself to another satellite.

JerryF

[quote author=JerArdra]... sometimes when you switched to another channel, and I do this often, the dish may have to re-align itself to another satellite.[/quote]

Interesting Jerry. In 6 years, our dome has not had to re-align itself when we switch channels. In fact, I always turn the controller off after getting situated in a campground, per the King Dome instructions printed on the switch. The switch is not turned on again until we get settled in another location/campground.

JerArdra said:

Bob,

I'm sure Dome Magic helps with dew droplets but dew seems not to affect dishes.  It's not fun to climb up on a wet, icy, or snow covered roof.  Also, it's not a very smart thing to do even with "original issue" hips!

Another gripe I had with the dome, in 2003, was that sometimes when you switched to another channel, and I do this often, the dish may have to re-align itself to another satellite.

JerryF

Click to expand...

I would agree, Jerry, and I have "never" done my roof when it was wet - for any reason or status of my hips.  My point was that Dome Magic is applied once a year -- and that one time is on a bright sun shiny and warm day when the roof and dome are dry. I clean the dome with simple rubbing alcohol before applying several coats of DM.

I probably out click most unless recording on both LNB's - and have never had a realignment problem. My dome is not fully automatic, so if realignment were necessary, I would have to do the remote and such. That "would" be a bummer, but has never happened. OTOH, the wind would often blow my crank up off alignment . . .

After that "super blow" in QZ last month, I came home after Lorna's solo for the week attendees dinner, turned on the TV, and watched the late news. No raising the dish or alignment necessary . . .

A nice cold dish and a nice dry snow and it doesn't cling at all unless the angle is shallow.  If you are in Maine and use Dish Network, nothing clings to an open face dish - it is almost 90 degrees to the ground!

That's it, I'm canceling DTV, signing up for Dish Network, buying a vertical dish, and we're going to winter in Maine.

Tom said:

That's it, I'm canceling DTV, signing up for Dish Network, buying a vertical dish, and we're going to winter in Maine.

Click to expand...

Did you get a recommendation from Fred as to which part of Maine would be best????

I'm sure I'll get plenty of suggestions  ;D

Clay L said:

And as you know the gain of a dish is proportional to the size so the smaller dish in the dome will always suffer from rain fade and the like more than a larger dish.

Click to expand...

Absolutely, and that's part of the point. You start out with a marginal gain reflector, than add further attenuation in the form of a dome. THEN it rains.....