The top doesn't obscure reception at all when up???

 

Nope. It has a clear view out the back window.

 

Yeah, but what about when you are heading due south and the satelite is obstructed by the top?

 

Dude, its not direct tv, where the dish has to point south. There is more than one in the air. I have never had an issue with my XM located back there.

 

XM has two satelites that are in geosynchonous orbit (the same spot all the time) in the southern sky. Sirius uses a few satelites that move and there is always one over head. If I am in front of a building more than two stories tall and directly to my south, I lose signal. Remember, I do not live in a major metro area like new york where they have terestrial repaters. If the antenna don't see the satelite, I don't hear no music

I drove through Boston yesterday and was amazed that with the terestrial repeaters, you can bee in between building sor in tunnels and still hear the music. I might be better off leaving my antenna on the trunk for my area. It actualy blends in OK being black and all and it is only about the size of a match book, not like the old school ones and the nasty OEM style.

 

Well...in that case, you may want to take my advice with a grain of salt. Im in NYC, and we have craploads of repeaters. However, on my drives to New England, South Jersey, or whenever I drive to nowhere, I have had no issues.

 

I will just test it out by placing it there and seeing what happens before I make it permanant.

 

alright - this is getting way off - so i did a bit of research.


don't fall into the trap of thinking that radio waves are limited to the same transmission lines as light (aka - if you can't see through it, neither can the antenna).

both sirius and XM operate in the 2.3Ghz range. that has a wavelength around 5 inches. considering our tops are tenths of an inch in thickness, they don't represent a really significant block to the radio energy. (i'd discuss Planck's Energy Equation, but it's a bit over the top for this discussion.)

from a more practical perspective, 2.4 Ghz is what most modern WIFI and cordless phones currently use... and those readily work through multiple interior and exterior walls, and often through major appliances.

i SERIOUSLY doubt that our thin vinyl top represents anything remotely resembling a "block" for the antenna.



as an aside -- GPS frequencies operate in the 390 to 1550 Mhz range.

 

Yup. My friend's home XM reciever in his basement has no problem picking up signal. Oddly enough, If I pull into his garage (same level as the basement) my car signal goes dead.

 

So then how can paper thin sheet metal of the trunk block the signal and the top doesn't? Why do tall trees near my house block the signal when they are to my south? My wifi card works fine in the trunk. All the documentation on sat radio is that it is line of sight, where as Wifi is certainly not. It is apples and oranges to compare the two for reception purposes. Sometimes the way things work in theory and how they actualy perform are two entirely different things.

This has been the same result with multiple antennas on the roofs of three different cars I have tested it with.