Antenna tower question

[Jeff K]

I have decided I need to do something drastic about this internet connection.
My ATT air card has a 5 gig limit. We hit the limit all the time
I got a Virgin Mobile card, it's unlimited but I just barely get service. My antenna for my ATT card works fine, but it my not be enough for the virgin card. So...

I'd like to put up an antenna tower to suck in some serious signal.

How high can I go without guy wires? My house has a Hip roof so I don't have a tall gable end to anchor to.



Any thoughts?

[BudMan]

Back in my active Ham days, I remember Rohn being the top quality of all of them.  This site is a great source for tower and antenna information.
http://www.eham.net/reviews/detail/6746

[Thunderbolt]

Push up pole, Rohn 20 or 25 triangular tower?  What type of antenna are you using as in is there an actual base loaded vertical antenna and what type of feed line?  You might consider just running a line over a tree limb with your antenna on it and make sure it's going to improve your signal before spending big bucks on the whole ball of wax.

[sugerbear]

is this the booster your talking about?
http://3gstore.com/index.php?main_page=product_info&cPath=202_266_430&products_id=2459

if so they say not over 3ft 7 in

[Jeff K]

This is the antenna I'm using now. they say it's a "line of site" antenna. I have it on a PVC pipe stuck on a dish mast on the roof, it was supposed to be temporary, but it been there for a year.I don't get a get signal there but it was doing the job. It's up about 15-18 feet.

http://www.wpsantennas.com/304411-Wilson-Cellular-Wide-Band-Yagi-Antenna.aspx

[Thunderbolt]

Yagi antenna's usually have 2 or three elements that make it directional, point here is that if it isn't aimed at the tower you are using for the signal, that could be part of the problem.  The next point to consider is the coax that you are using to feed it.  The lower loss cable if you aren't already using it, could be a big help.  The loss on the "better" cable is about 1/3 the loss on the rg58.
So if you aren't using the better cable, get some with the proper connectors, and if you can "aim" or point the antenna while watching your signal strength meter you could improve the signal dramatically.  I would try that first.

[Pete]

Jeff,

As I understand it in the bands you will be using, everything is line of sight.
I suspect your antenna is fine, just go higher and check you alignment with the other sender receiver tower.
You are using low loss co-ax? Right.

Good luck.

[NCGhostrider]

Rohn 25 tower is probably your best bet, you can probably do an anchor from the eave of your house and easily go 40' with the minimal load you are showing.  You must switch to the LMR coax as they recommend on the wilson site, rg58 will lose most of the signal you would gain at anything beyond 20ft lengths.. I would guess.   

Be aware that many places prohibit via CCR's etc the installation of towers or antennas of any kind without prior approval or even permits.  We ham operators fight that stuff all the time.  We usually win because of the licensing thru the FCC etc...but it is a pain.

Most, if not all push poles will require guying etc.   

You might look on eham.net as suggested for ideas... craigslist often has towers listed, and if you can find a local ham operator, they might help you out with the tower, and the proper install/antenna installation...depends on their attitutude.  I didin't look at the specs on the antenna you linked to, but if it is directional, you need to verify direction and possible aim it while on the roof with your laptop...yes, I know, it sounds wild, but I have done it before with a radio or two.

An alternative route, might be a roof mount tower, not sure of vendors, but they can be built, out of square tubing and a little work... good for 10-12 foot easily above roof line.

BTW, I have antennas all over the house, mostly wire lines (dipoles)  but, its my other hobby...

good luck!!! 

Craig
KC5PGZ

[Jeff K]

I am using LMR cable already. About 50' of it. I'll need more to go higher.

This is a local CL ad I was looking at.

http://tampa.craigslist.org/hil/ele/2138917031.html

[Thunderbolt]

and connectors have loss too especially if not done properly.  If you buy that tower and don't want the rotor, I might be interested in it.
You might also consider another amp specific to the frequency that you are using instead of the wideband that you have now.  Frequency specific amps usually have more gain where you need it.

[NCGhostrider]

That tower is probably a steal!   If you can get an eave mount on the house near the top of the bottom section, it should be designed to go with guy wires.   What Thunderbolt said about the connectors is also very true.

I wish you could verify that you could "see" the signal before you invested the time and money on the upgrades.  Sometimes it just isn't doable at certain frequencies.   Do you know how far you are from the site you are aiming the antenna at?   

I was a tester for Nextels broadband over wireless back several years ago.. it worked pretty decent around Raleigh, I was on the fringe out near where I was living North of town.  I had access to a lot of antennas from some friends in the cellular world, but the terrain prevented me from getting a good constant signal even with height and enhanced directional antennas.   


Keep us posted... if I can help, I will try. 

See ya..

[RedValk]

Rohn HDBX is relatively cheap (compared to other stand alone towers) and can go to 64 feet. I have Rohn HDBX....but only went to 48 feet...as i have a 100 pound, 4 element beam with a 42 foot driven element on it for 40 meters (Ham)! So i couldn't go the full 64 feet and stay within wind loading specs.

[Jeff K]

So when I go look at this tower how will I know if it can be free standing?

[RedValk]

Rohnd HDBX is stamped as such on the legs...and ...it has riggid thick cross members running up the legs of the tower. Most "guyed" type tower either has just horizontal supports on the legs...usually just tubular bars....or they may have ONE diaganol support member too. HDBX has thick crossed members....thus making it harder to climb, by the way.

of course, there are some other free standing tower manufacturers...including some made of thick aluminum i believe. But i think you'll find they cost more than Rohn HDBX. They also have a BX model, that takes smaller wind loads. Your application i would think should have minimal wind load at the frequency you are talking about?

Also, you could use some "guyed" type tower pieces...if you don't go too high...and have it attached somehow to the side of the house....etc. as long as you both don't go too high and don't have too much wind load.

for your application, i would think you could just use TV mast ....attached off the side of the house or on a chimney mount or tripod roof mount? your antenna i would think for the frequencies involved should be pretty small?

My application, which has mutlitple Ham antennae...including a 40 meter beam...has quite a bit of windloading...and weight. the one antenna weighs just under 100 pounds...has a 14 foot boom...and a driven element that is about 42 feet long! So i needed the HDBX for the wind load i'm talking about!

Of course, in the Ham world, the old joke is if your antenna doesn't eventually fall down, you either didn't go big enough on the antenna...or didn't go high enough...

[Jeff K]

Rohnd HDBX is stamped as such on the legs...and ...it has riggid thick cross members running up the legs of the tower. Most "guyed" type tower either has just horizontal supports on the legs...usually just tubular bars....or they may have ONE diaganol support member too. HDBX has thick crossed members....thus making it harder to climb, by the way.

of course, there are some other free standing tower manufacturers...including some made of thick aluminum i believe. But i think you'll find they cost more than Rohn HDBX. They also have a BX model, that takes smaller wind loads. Your application i would think should have minimal wind load at the frequency you are talking about?

Also, you could use some "guyed" type tower pieces...if you don't go too high...and have it attached somehow to the side of the house....etc. as long as you both don't go too high and don't have too much wind load.

for your application, i would think you could just use TV mast ....attached off the side of the house or on a chimney mount or tripod roof mount? your antenna i would think for the frequencies involved should be pretty small?

My application, which has mutlitple Ham antennae...including a 40 meter beam...has quite a bit of windloading...and weight. the one antenna weighs just under 100 pounds...has a 14 foot boom...and a driven element that is about 42 feet long! So i needed the HDBX for the wind load i'm talking about!

Of course, in the Ham world, the old joke is if your antenna doesn't eventually fall down, you either didn't go big enough on the antenna...or didn't go high enough...

The antenna is small. It's less than 1 sq foot. But I want it up about 40' My house is single story Hip roof. So I can't get much support from the house since the eve is only 8'.

[RedValk]

Yagi antenna's usually have 2 or three elements that make it directional, point here is that if it isn't aimed at the tower you are using for the signal, that could be part of the problem.  The next point to consider is the coax that you are using to feed it.  The lower loss cable if you aren't already using it, could be a big help.  The loss on the "better" cable is about 1/3 the loss on the rg58.
So if you aren't using the better cable, get some with the proper connectors, and if you can "aim" or point the antenna while watching your signal strength meter you could improve the signal dramatically.  I would try that first.

another VERY good point. at the frequencies you are talking about, typical coax cable many people use (RG-58 for 50 ohm, RG-6 or RG-59 for 75 ohm) have LARGE loss at the frequencies you're are talking about. from the chart at the URL listed below....for instance...RG-58 has a loss of about 14.5 db per 100 feet at 900 Mhz. So for 800 Mhz...probably just under 14 db! To put that in perspective, every 3 db means you've lost about  HALF the power (or signal in...it works both on RX and TX). Even larger cables have lots of loss at these higher freqs (but less than the thinner/higher loss coax cables)! that's why Hams and commerical folks go to more expensive hard line at freqs like that.  So, 6 db loss would mean about 1/4 the signal gets to your receiver on the incoming signal...and about 1/4 of what you transmit makes it to the actual antenna...assuming no SWR issues. 12 db of loss would mean about 1/16th of your signal arrive at the antenna on output or came in to your receiver! 15 db of loss would mean about 1/32 of the signal was there! (this is for RG-58....a 100 foot run. obviously, shorter runs would have less loss). now, add any loss for connectors...even more loss for cheap or improperly terminated connectors. Yea, AT THESE FREQS...it REALLY adds up! the higher you go in freq, the more critical it is. SWR issues, means even MORE loss.

this is why your satellite TV has an LNA/LNB ....to amplify that incoming signal to overcome some of that coax loss to get the signal to your TV!

basically, for every 3db of loss, decrease by half (for every db of gain...like in your antenna gain...multiple by a factor of 2). 6db loss is one quarter of the signal, 9 db loss 1/8....12 db 1/16...etc.

Helpful chart for other coax/freqs is here in this link:

http://www.therfc.com/attenrat.htm

[RedValk]

i note the ant manufacturer web link you listed, of course says as a yagi type antenna...you DO have to point it towards the cell tower you want to use for your signal. you'd have to somehow find out what Azimuth that tower is from your location (or, if you have some kind of signal strength meter/reading...you could move the antenna while watching signal strength...and point for max signal). granted, i doubt the 3db beamwidth of this small yagi is THAT directional...ie...it probably has a 3db beamwidth on the order of 60 degrees or so...i'd bet. So, that means....you'd only have to get "ball park close" on the azimuth for it to work.

also, quoted from their site:

the antenna includes no cable. For a short run of 20' you can use our 20' RG-58 coax extension which has the appropriate connections for the Yagi. Please note that our other RG-58 cables can not be directly connected to the Yagi antenna.

For longer runs, we suggest using one of the below lengths of Ultra Low Loss LMR-400 Cable. This cable is fairly stiff so if you plan on connecting the Yagi directly to your phone with an antenna adapter we suggest you also include an 5' RG-58 extension. The below cables may also be connected together using the N-Female to N-Female barrel connector.

The primary difference between RG-58 and LMR-400 is the dB signal loss. RG-58 loses approximately 12dB/100' while LMR-400 loses about 4dB/100' (which is a big difference).

big difference indeed! 12 db that they quote...is roughly 1/16 of the signal. so, i note they list anywhere from 8-10 dbi of gain for this antenna...depending on the used freq. First, that means your coax loss....for RG-58....for a 100 foot run....THAT LOSS WOULD EXCEED THE GAIN OF THE ANTENNA. IE, your losses would override any gain the antenna was giving you (ok, not looking at antenna height....and other factors). bottom line, for a LONG run of RG-58....you'd be WORSE off probably...or certainly not worth the effort/dollars spent! their low loss cable (more along the lines of my earlier post about hardline type coax)...gives you 4 db of loss per 100 foot. a little more than half the signal lost. A CONSIDERBLE gain...over 1/16 of loss!

other things to consider...don't mix and match coax types. NOT JUST...the impedance. Of course, mixing 75 ohm with 50 ohm would be disaster with huge SWR issues (ie mixing RG-58 and RG-59). But even mixing various types of 50 ohm coax (RG-58 with RG-8 or RG-213, for instance)...can have serious issues on longer runs and higher freqs (your application IS HIGH freq). Different types of coax have different capacitance per 100 foot and different velocity factors. Translation .....MORE SWR issues....equals more loss.

you can easliy lose any gain the antenna gives thru poor/improper coax, connector loss, etc.

i know, this is probably FAR more than you ever wanted to know. But, i used to work in this field for 10 years in my early days as an Electrical Engineer...and as a Ham radio operator, i frequently still play with this "stuff".

one more thing. they rated the antenna in dbi. dbi is a reference to an isentropic radiator. IE, a hypothetical vertical antenna with no gain or unity gain in all directions. so ...in essence, they're saying this antenna has about 8-10 db of gain....verses NO antenna. that means about 8 times the gain roughly...compared to no antenna. whenever comparing antennae, make sure you note if the gain is referenced in dbi...or the better dbd ...a reference commonly used to a half wave dipole. just saying, if comparing antennae....make sure when you look at that gain reference, you're comparing apples to apples...and not apples to oranges (which would be the case of one antenna referenced to dbd and another referenced to dbi). Most manufacturers use dbi...as it gives a sense of MORE gain (the gain number is higher compared to no gain...or unity gain).

[RedValk]

ok, it's "better" than i thought (actually....sort of worse...it's less directional than i guessed...i guessed "about 60 degrees"). from the web site:

Horizontal Beamwidth 70 to 90 Degrees
Vertical Beamwidth 85 to 110 Degrees

so, it's not very directional at all...which makes sense...it's VERY small....and doesn't have many elements. so finding "the sweet spot" shouldn't be that hard...it will have a very broad "swath" in azimuth that will give similar signal strength readings.

I have a 14 element meam for 145 Mhz....that has a pretty narrow beamwidth (about 10 degrees...as i recall?). that means, you have to point that antenna VERY carefully to get the gain of the antenna. Get a little off in direction, and your gain falls way off.

for you, this antenna you have is much more forgiving in finding the proper direction.....

[RedValk]

from the manual...for finding max signal (you probably already knew this):

Adjusting the Antenna for Maximum Performance
To adjust the antenna for best performance, connect it to your cell phone with an external
adapter and a length of coaxial cable. External antenna adapters and coaxial cables
are sold separately. Put the cell phone in test mode and turn the Antenna in 10-degree
increments while checking the cell phone’s signal level. At each point you may need to
wait a few seconds as your cell phone updates. To f nd your phone’s test mode, visit
www.wilsonelectronics.com. Signal readings usually appear as a negative number (for
example, -86). The larger the number, the more powerful the signal (-75 is stronger than
-84).

[Jeff K]

I have 50' of LMR 240 coax. The antenna setup works fine with my ATT modem. though it only shows a -90 signal, it is functional for web surfing.
I am waiting for the cable adapter to come for the new Virgin Mobile modem. Though the ATT cable fit, it didn't make any difference on the signal. The antenna place said that they were close but not exactly the same. So I ordered the "correct" one. If it works as well as the ATT does I'm fine but if not I'll need to go up.
I could go up higher and keep the cable the same length if I poke a hole in a new spot closer to the outside wall and move the router.

[RedValk]

-90 is about the ballpark range i have on my Verizon service...for my LG Android. MOST of the time it works (at my home ...in the sticks of Bama'....it ALWAYS works great in the big city of Montgomery). But SOMETIMES, the signal drops a bit ...into the mid 90s...and then my connection slows considerably. Once in a while it drops out completely...like i'll be downloading an MP3 file...and it won't do it. I'll walk over to the kitchen window....hold the phone up to the window...the signal picks up..and the download proceeds.

I just live with the borderline signal at times. i have my pcs "tethered" off of my phone too...to get "high speed" internet. again, it's much better than my dialup....but...the signal goes up and down and once in a while drops out. not alot of choices out here in the sticks.......

sounds like you have good cable. i'd try not to go too much longer on the coax...if at all. more height with the same length of coax of course could/probably would help. that antenna is light....you should be able to go up with tv mast or just about anything. I have a small TV yagi on TV mast...up about 25 feet. i attached it to the eve...about 10 feet up. there is another 15 feet above that unsupported. i wouldn't want to go any higher...with no support...but it works with that light antenna.

[Thunderbolt]

with a metal standoff.  You probably would want to keep the foldover capability for changeout of parts in the future.  That is a good price if it works.  I would pour a little concrete to tie it to the ground.  You could put a TV antenna with a booster attached and probably get plenty of stations.

[Jeff K]

I went and looked at it. It all aluminum. It has a steel tip up base plate and the underground posts and rebars. The aluminum tower has a hand crank, not like a boat crank, but an all aluminum hand crank.
It has an antique rotor and rotor control.

I think I'm going to give it a shot. I'll anchor it in concrete and use the bracket to the house. If a hurricane comes I can drop it pretty quick.

[IamGCW]

Jeff
Watching this thread and agreeing with the line loss for long cable.  The tower you are looking at is pretty nice.  From the location of the CL add I suspect you are in the Tampa area.  Be aware you are also raising a lightning rod.  Central Florida is known to be a top producer of lightning.  So when you plan out your job proper grounding for lightning and always watch for overhead power lines.  A sturdy concrete base with long J-bolts should make the unit strong.  Also many people like to put little weather stations on their towers.  Good luck

[RedValk]

cranks ups are NICE! Wish mine was a crank up. i have a DX sloper antenna (160/80/40 meter sloper wire ant) waiting to install ....i got the antenna for Christmas to replace my existing broken one of the same kind. that means, i need to climb the old tower to install it! i'm waiting for some nice weather to put my climbing belt on.

my tower ...being free standing...has a 5 and a half foot cubic hole...filled with the same high grade concrete they use to build bridges...and 20 foot of rebar. It's not going ANYWHERE! this same tower and set up....which i've now had some 21-22 years....has been thru:

Hurricane Hugo....135 mph winds at my house....
Hurricane Opal...90-100 mph at my house....
Hurricane Ivan...70-80 mph at my house...

numerous high wind storms....

numerous ice storms....

every 10 years i repaint it with rustoleum grey paint (from the spray can). I'm in the middle of that "paint job" now...again waiting for good weather.


bottom line,  a tower can be a VERY long term investment...if you do it right and take care of it........


And roger on the lightning rod! my tower...which has two 10 foot 5/8 ground rods at it's base...has been struck over those 21-22 years....several times. How do i know? a couple of those times i was at home...and YOU KNEW...when it struck and hit!!!!  also, when it strikes....it discharges into my chain link fence nearby. when it does that, all the gate handles on any gates....get "arc welded" closed. you know, where the latch meets the pole....it's not a perfect mechanical "bond"...so...when the lightning discharges thru it...it "welds" the gate shut! i have to go out with a maul and bust it back open!!! you can look at all my gate latches now and see just where it has "welded" shut...and i've busted it lose. there is no mistaking it....

now, with all those strikes....ZERO damage to ANYTHING inside. Meanwhile, my direct TV dish has been struck twice...and it is NOT grounded as well....and it has been toasted both times. GROUNDING IS CRITICAL! (plus i unhook all my ham stuff when not in use).