Masthead mobile internet/phone antennas

[Snowpetrel]

Anybody used a masthead mobile phone antenna of any sort. What are the pitfalls?

I can see signal strength losses being a big one on a tall mast. Most antennas only seem to have 5 meters of cable. I guess I would plug it into a wifi router at the base of the mast. Not after super speeds, Just seems like a good way to reduce the black holes in enclosed bays and give extra range offshore. There are some very expensive units with amplifiers and the like at $1000 or so. and much cheaper $30 antennas.

Seems like a small antenna would beat the hastle of having to hoist the router or phone up the mast in a plastic bag, or climb up to the spreaders just to get a few bars of signal.

I am based in Aus and currently using the telstra network.

[Bruce K]

Have a look at these guys, I found them unbeliveably helpful, ZCG Scalar, www.zcg.com.au

[Wotname]

^^ another vote of confidence for ZCG, they make good stuff!

[Snowpetrel]

Thanks, quite an array of antennas availibke from them. Some of them say mount as high on the deck as possible, others say mount as high on the mast as possible. I guess it may be worth am email to find out the limits on coax length.

[Bruce K]

I just phoned them and had a chat about what I wanted to do, then ordered my antenna thru a local supplied reccomended by ZCG, they have great knowledge about things RF.

[Bruce K]

Snowpetrel, just noticed you are in Hobart; Moonraker in Derwent Park make an amazing array of antenna, mostly big end/military stuff, but exceptional quality. I have found them a bit difficult to get on with, but as you are there maybe worth a call.

[Wotname]

IMHO, I would go the ZCG for quality commercial stuff (VHF and upwards) and Moonraker for HF and all things military. In another lifetime, we were agents for both.

YMMV.

EDIT: RFI (Aust) make excellent antennas of all types but IME, you won't get much advice from them at the retail level. They do have very good support for their agents though.

In Tassie, I can highly recommend these guys - IME, extremely knowledgable and helpful. http://taselectronics.com.au

[Snowpetrel]

I guess the big issue is if 52 foot of mast is going to cause too many issues, so a call to them makes sense. It would also give me a rough idea of price and if there is likely to be any clash with the VHF. Prehaps mounting the 4g antenna on the upper spreader might solve both issues.

Another cheap and easy thought is to rig up a waterproof case for my wireless 4g router/modem thingy and just figure out a way to hard wire a power supply for it up the mast or on a spreader after testing the wifi range will reach the cabin. Maybe there is some way to boost the wifi signal or send it down the mast via ethernet cable? I know my phones hotspot only had about a 20 foot range. I haven't tested the fancy modems max wifi range.

[Jerry Woodward]

Since cell towers are well, towers, and then generally mounted on hills at the highest point, I wonder whether you gain anything by mounting a cellular antenna at the top of the mast. I think the angle from the cell tower down to the boat would be pretty much the same whether to the top of the mast or to the stern rail. If you are far enough away to make the earths curvature come into play, I don't think you would be receiving a cell signal anyway. I have mine mounted on the stern rail and it has been working great off the west coast of Florida. Of course, I have never directly compared stern vs mast mount.

I am no expert and I would love to hear an expert discuss this issue.


I think the more important issue is that you get a MIMO omnidirectional antenna (two antennas inside a radome) and run two coax cables (they are pretty thin). Here is my antenna, very well made and works well.


https://www.semiconductorstore.com/c...dproduct=71870

[Auspicious]

I have an RR Elektronische Pacific. It works nicely. The key to multiple antennas at the masthead is something designed well to avoid issues with interactions between the elements. This is non trivial. If you just want to add something and avoid conflict with your masthead VHF I would avoid the masthead and add cell, WiFi etc on spreaders, bimini top, or pushpit.

[boatman1]

Several years ago I looked into this and was informed that there is a certain distance from a tower to your device beyond which the time delay in the signal is excessive and the system won't communicate with you. I don't know if this is still the case or whether the providers have allowed for an increased delay: if memory serves, the line of sight distance beyond which service won't function was 12 miles?

[Comix Bay]

Originally Posted by boatman1

Several years ago I looked into this and was informed that there is a certain distance from a tower to your device beyond which the time delay in the signal is excessive and the system won't communicate with you. I don't know if this is still the case or whether the providers have allowed for an increased delay: if memory serves, the line of sight distance beyond which service won't function was 12 miles?

It must be greater than that now, if i am down on the beach by Cape Lazo, BC and use my IPhone I get long distance charges from Powell River, BC which is approx 19 miles away. The same in Victoria, BC, you have to be careful down on Dallas Rd you may be picked up by Port Angeles, WA (app 21 miles) and then you are subject to both LD and roaming charges. Atmospheric & Wx conditions play a part in this also.

[skipgundlach]

I don't have one so can't knowledgeably comment on them, but there are combo cell and WiFi systems you mount with the antenna attached, and run a cat5 cable for data, and make a repeater out of it for cell (I think is how the combo works).

For the WiFi alone (I know that's not what you asked) it's definitely the case to put it up and in this case, power it over the unused lines in a cat5 (power over ethernet, POE). In our case it has worked wonderfully for 12 years...

[Auspicious]

Originally Posted by boatman1

Several years ago I looked into this and was informed that there is a certain distance from a tower to your device beyond which the time delay in the signal is excessive and the system won't communicate with you.

True. The issue is most prevalent in TDMA systems like GSM where you fall out of your time slot with distance. CDMA is a little more robust but there are still timing issues. I don't remember the numbers but if you look up GSM and find the time slots and use the speed of light in air if you slide out around 50% of a time slot it won't work.

The more robust coding of CDMA (especially WCDMA) is why sometimes you'll get LTE coming in from offshore and then drop back to stronger 3G before getting LTE again.

[svlamorocha]

Originally Posted by Auspicious

True. The issue is most prevalent in TDMA systems like GSM where you fall out of your time slot with distance. CDMA is a little more robust but there are still timing issues. I don't remember the numbers but if you look up GSM and find the time slots and use the speed of light in air if you slide out around 50% of a time slot it won't work.

The more robust coding of CDMA (especially WCDMA) is why sometimes you'll get LTE coming in from offshore and then drop back to stronger 3G before getting LTE again.

I was told that in GSM the maximum distance to tower is 35km but some networks have an "extended range" feature that changes the timing to allow 150km range, subject to signal strength. I believe this feature may be available in BVI or SXM because I managed to get a text out (from my Blackberry hoisted up the mast) just in the middle of the Anegada passage.