Multiple Antennas at Masthead?

denverd0n · 07-10-2009, 12:52

Marine VHF antenna obviously needs to be at the masthead. I am planning on installing a cellular repeater and it would be good for that antenna to be at the masthead also. And then there's the wifi...

I'm picturing a very crowded masthead! All these different gadgets use frequencies that are far enough apart that I'm hoping there won't be a huge problem with interference, but simply the physical challenge of three antennas at the masthead seems daunting. Anyone ever attempt something like this? Have pictures?

I'm imagining a Y-shaped mount with legs about a foot long.

Or am I crazy?

colemj · 07-10-2009, 13:03

There are mounts made specifically for increasing the mounting area of mastheads. They are an elliptical piece of square tubing with mounts for the existing masthead. Hard to explain. Also, there are offset antenna mounts available.

Mark

hellosailor · 07-10-2009, 14:33

You might not want the cellular antenna at the masthead. You may see so much loss in the cable leading up to it, that it totally nullifies the power of the repeater/booster. Check the db loss per foot carefully for the cable, before you invest time and money on that.

denverd0n · 08-10-2009, 06:20

The cellular repeater that I'm considering is this one...
PowerMax 4KSBR-50M 70dB Gain 4,000 SF Wireless Cellular Repeater System - Large Boat Home Office RV Cell Booster

It comes with a 50' long cable for the external antenna. I am assuming that they provide an appropriate cable for that run, but I suppose this might be a case of ASS-U-ME!

hellosailor · 08-10-2009, 12:06

They do have a data sheet, their DA340 cable supposedly loses some 8.5db per hundred feet at 1900MHz, while their DA440 loses only 5.8db. (The DA340 loses twice as much signal as the better quality cable, which I'd bet is way thicker and heavier.)

The 4db cable loss isn't bad, but it still means they are losing more than 1/2 the incoming signal in the cable. Still...and without running all the numbers...as a system it probably has enough gain to be useful.

There are limits in the software used in the cellular system which look at the signal delay times for any given call, and even if you can work a tower, the tower is told to drop you if you are something like 32 miles away from it. The system assumes there will always be another tower closer than that--or, you really don't matter to them anyway.

speciald@ocens. · 08-10-2009, 14:17

I have a Digital Antenna wireless cellular booster and have not been impressed that it does much at all. Verizon guys came down the dock once trying to find some source of interference with their network. It was my booster so I guess it does something.

denverd0n · 09-10-2009, 09:10

Can you provide anymore details about your Digital Antenna booster? Which model? Where have you mounted the external and internal antennas?

Thanks!

speciald@ocens. · 09-10-2009, 09:39

I have the Powermax 4KSBR-50M wireless. The external antenna is mounted on a Kato stern pole with the internal antenna right next to the amplifier in a cabinet in the aft cabin.

07-10-2009, 12:52	#1
denverd0n Registered User Join Date: Jun 2008 Posts: 79	Multiple Antennas at Masthead? Marine VHF antenna obviously needs to be at the masthead. I am planning on installing a cellular repeater and it would be good for that antenna to be at the masthead also. And then there's the wifi... I'm picturing a very crowded masthead! All these different gadgets use frequencies that are far enough apart that I'm hoping there won't be a huge problem with interference, but simply the physical challenge of three antennas at the masthead seems daunting. Anyone ever attempt something like this? Have pictures? I'm imagining a Y-shaped mount with legs about a foot long. Or am I crazy?

07-10-2009, 13:03	#2
colemj Registered User Join Date: Oct 2005 Location: Heading South Boat: Manta 40 - Reach Posts: 497	There are mounts made specifically for increasing the mounting area of mastheads. They are an elliptical piece of square tubing with mounts for the existing masthead. Hard to explain. Also, there are offset antenna mounts available. Mark __________________ www.svreach.com

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07-10-2009, 14:33	#3
hellosailor Registered User Join Date: Apr 2006 Posts: 3,993	You might not want the cellular antenna at the masthead. You may see so much loss in the cable leading up to it, that it totally nullifies the power of the repeater/booster. Check the db loss per foot carefully for the cable, before you invest time and money on that.

08-10-2009, 06:20	#4
denverd0n Registered User Join Date: Jun 2008 Posts: 79	The cellular repeater that I'm considering is this one... PowerMax 4KSBR-50M 70dB Gain 4,000 SF Wireless Cellular Repeater System - Large Boat Home Office RV Cell Booster It comes with a 50' long cable for the external antenna. I am assuming that they provide an appropriate cable for that run, but I suppose this might be a case of ASS-U-ME!

08-10-2009, 12:06	#5
hellosailor Registered User Join Date: Apr 2006 Posts: 3,993	They do have a data sheet, their DA340 cable supposedly loses some 8.5db per hundred feet at 1900MHz, while their DA440 loses only 5.8db. (The DA340 loses twice as much signal as the better quality cable, which I'd bet is way thicker and heavier.) The 4db cable loss isn't bad, but it still means they are losing more than 1/2 the incoming signal in the cable. Still...and without running all the numbers...as a system it probably has enough gain to be useful. There are limits in the software used in the cellular system which look at the signal delay times for any given call, and even if you can work a tower, the tower is told to drop you if you are something like 32 miles away from it. The system assumes there will always be another tower closer than that--or, you really don't matter to them anyway.

08-10-2009, 14:17	#6
speciald@ocens. Registered User Join Date: Apr 2008 Location: On the boat - Carib, Chesapeake Boat: 58 Taswell AS Posts: 411	I have a Digital Antenna wireless cellular booster and have not been impressed that it does much at all. Verizon guys came down the dock once trying to find some source of interference with their network. It was my booster so I guess it does something.

09-10-2009, 09:10	#7
denverd0n Registered User Join Date: Jun 2008 Posts: 79	Can you provide anymore details about your Digital Antenna booster? Which model? Where have you mounted the external and internal antennas? Thanks!

09-10-2009, 09:39	#8
speciald@ocens. Registered User Join Date: Apr 2008 Location: On the boat - Carib, Chesapeake Boat: 58 Taswell AS Posts: 411	I have the Powermax 4KSBR-50M wireless. The external antenna is mounted on a Kato stern pole with the internal antenna right next to the amplifier in a cabinet in the aft cabin.