captive apple

Any WiFi experts?
Why is the WiFi hump on a 737 so huge compared the two antennas on a CRJ700?
Different company?
Different tech?
Also bottom mounted vs top?

m3113n1a1

Ground based vs. satellite. The airplanes with satellite internet/tv have the hump and airplanes with ground based wifi do not.

Larry in TN

If I could be pedantic for just a moment...

The external antenna is not a wifi antenna. Wifi is how the airplane's network connects to the passenger's phones and tablets. The wifi antennas would be small and are hidden out of sight in the cabin. Depending on the airline, the airplane's wifi network may deliver internet, flight information, live TV, music, and/or on-demand movies.

The external antenna is for the airplane's internet connection. It can be for connecting either to a ground-based network or satellites. Ground-based and satellite connections are in different bands and have very different demands on the antennas so the hardware will be significantly different. The satellite systems have to track the satellites. They do this electronically, instead of mechanically, but it's like aiming your home satellite dish at the satellite in orbit.

The reason all of this is important is that when part of the system isn't working correctly, which is fairly common, the write-up needs to correctly identify the part of the system which isn't working. A lot of people just write up the "wifi" which could be working fine.

CrowneVic

............//s

flensr

Some are still mechanically aimed. The flatter ones are electronically aimed, the higher profile ones have a steerable antenna inside. Here's a brochure for a fairly common one and you can see in the specs it's mechanically aimed.

https://www.astronics.com/docs/defau...om-antenna.pdf

I don't have stats but based on mil experience with both types of antenna, I would assume that the mechanically aimed ones are cheaper to buy but are less reliable. Maintenance costs could be about the same since routine maintenance on the mechanically steered ones could be high due to higher failure rate on moving parts, but when the electronically steered one fails the parts are probably quite expensive.

Name User

I don't know about this specific case but in general electronics are cheaper over the long run. They last 8x-10x as long but cost 2x-3x as much. That is just a general rule for replacing mechanical instruments with digital/electronic ones in aircraft.

rickair7777

All else being equal, yes solid state antenna arrays will be more cost effective and more reliable (and typically perform better) than mechanically steered equivalents.

Antenna equivalent of transistors vs. vacuum tubes in your TV.

fasteddie800

In general, my experience has been that the ground-based stuff has never lived up to expectations. When it actually works, it's OK (slow, but OK). However I've rarely been on a flight where it's worked seamlessly throughout the entire flight.

It seems like the industry is moving towards satellite based, along with promises of high bandwidth, low latency, guaranteed seamless service, etc.

From a high-level perspective, I have a difficult time believing it. I just don't think the technology is there to maintain an aircraft-to-satellite connection for an entire 3-hour flight with enough bandwidth to support the 50-100 or more personal devices people will be using in the cabin. Hoping that industry proves me wrong, but I just have a hard time believing it. Open to differing viewpoints though.

bitwiser

Just wait until SpaceX's starlink and other similar low-earth-orbit systems come online in a few years. You will have a wifi connection in the airplane likely as good as what you have in your house right now.

fasteddie800

Ehh, I feel like Gogo used to say the same thing ~10-15 years ago.