A Guide To Masts For Aerials & Antennas
I recently wrote a blog on the types of wall brackets for TV aerials & satellite dishes and I thought that the natural partner to this would be a blog on different types of bracket/ mounts for aerials, so here you go. In this article I will discuss many of the common types of masts along with how we difference between them. This includes metals used, shape, wall thickness and diameter to help you pick the right aerial pole for your own aerial installation. What are we waiting for? Let’s begin.
Aerial Masts Lengths/ Heights
Perhaps the main differentiator between aerial poles would be the height of the thing. As not all antenna installations are the same the aerials need to be installed higher of lower depending on the installation. This may be that height is needed to help you get a stronger signal and look over nearby obstructions like neighbouring buildings and trees. To do need a larger mast is needed. Or It maybe that you want the installation looking as discreet as possible in which case a smaller mast would be required.
It is important when installing masts for TV/ FM aerials that 1:5 ratio is followed. This is that the bracket size and spacing should be no less than one sixth of the overall mast height. For large poles and high gain TV aerials & FM aerials which are typically much larger in size I would advise perhaps an minimum of 1 quarter of the overall mast height to allow for wind loading etc. This may mean having to install double lashing brackets to support your antenna on the chimney and T and K wall brackets to support it on a wall. Also, when installing masts higher it’s important that a thicker diameter poles is used with a thicker wall gauge, otherwise it’s likely to snap in a strong wind. I will get to this later on in the blog.
Common Aerial Mast Heights
Mast can be purchased in all of the following heights:
3’ ,6 ,8’,10’,12’,16’, 20’
Plus a few more. It wouldn’t be economical to stock all of these on your van if you’re a professional aerial installation. I stock mainly 6’ masts personally. These are fine for 90% of aerial installations in my area. If they are a bit long a bit can always be hack-sawed off the bottom of the pole. I also keep a few 10’ masts on the van and one 12’. To be honest I very rarely use 12’ masts these days. If I need a 16’ mast in I will order this in special for the job. I also stock a few 3’ J masts which I will come to in mast type.
Mast/ Pole Diameters For Aerials
As I already touched upon the higher the mast height the larger the bracket size and mast diameter to support it. Mast diameters for TV/ Radio Aerials are commonly available in the following diameters. I have written these below with my personal suggested maximum height to install these:
1” diameter – 5’ maximum height (I personally only use the J mast types which are 3’)
1.25” diameter – 6’ maximum height
1.5” diameter – 10’ maximum height
2” diameter – 10’+
I hope the above helps you pick the right mast diameter for you based on the height. Please note that when you get to the 2” diameter masts the small V bolts will no longer fit, you will need large V bolts. A 3” diameter pole is also possible to purchase but to be honest these are not common and you would need a special clamp to attach the aerial to the pole. It wouldn’t fit out of the box. It’s also worth mentioning that you could use a 1.5”diameter mast below 6’ and a 2” below 10’.
Aerial Mast Gauge / Wall Thickness
The next item for consideration is the wall thickness of the pole. This is commonly known as the mast gauge. Again like where the mast diameter should be increased you should also consider increasing the wall gauge too. This is because the smaller mast heights will have a lot less wind-loading on them and are a lot less likely to break in high wind. I should also mention that the smaller the number in gauge is actually thicker in mm. This is very similar to the AWG system. Mast/ poles for antennas can commonly be purchased in the following:
20G – 0.9mm – This is very thin, I don’t these
18G – 1.2mm
16G – 1.6mm – I use these mainly
14G – 1.8mm – These are good for high masts and satellite dishes where mast movement needs to be minimal
Scaffold type masts can also be purchased which have a 4-6mm wall, these are very strong and can be used for installation where they must be as close to no mast movement as possible. I would use these for satellite dish installations and a client that we install wireless broadband systems for, as they insist on the use of these to minimise mast wobble. Obviously, these are very heavy and not the easiest thing to getup and down a ladder so please be very careful if you’re installing these and it may require two of you to do so. Also because of the high metal content they cost a fair amount more also.
What Are TV Aerial Masts Made Of?
There are a few different metals which are used for TV aerial and satellite poles/ masts. The main two are aluminium and steel. Each of them has their own benefits. Steel typically is stronger but aluminium doesn’t rust. Of the two I would choose aluminium as do most other aerial installers and I would recommend choosing a mast with a decent wall size as suggested above.
The only time I would choose a steel mast would be for a satellite dish as this wobbles less and this would typically be in the form of a scaffold style pole. Even then I would try and obtain a aluminium scaffold pole instead. Again, the problem with steel is that it rusts, when it rusts it becomes significantly weaker and likely to break. Most steel masts for aerial/sat are galvanised. This means that the pole has been hot dipped in zinc to help preserve it. As the zinc coating doesn’t coat the inside of the pole as well as the outside these usually rust from the inside out meaning that the mast could actually be in far worse condition than it looks. You can also obtain anodized aerial masts but the coating on these is not as good as the galvanised masts. I would choose the latter. Of course you could try and find a stainless steel pole but I have yet to find one.
Aerial Mast Types & Designs
So far I have discussed the aerial mast length, diameter,wall thickness and metal used. Now I will discuss the mast types to help you choose which pole is best for your installation.
As it sounds, just a straight pole. No need to talk any more about this.
Crank masts are used to get around and above obstructions.Like fascia, soffits and gutters or brick that extend out at the top of the chimney. I must admit that I try to avoid these where possible as a far stronger fixing can be achieved with a straight mast. T and K wall brackets can be used to help get the spacing around and above obstructions. But from time to time these have to be used. Most crank masts are 6’ and come in a choice of a 1” diameter and a 1.25” diameter. I would definitely advise choosing the 1.25”.
There are couple different types.
Swan Neck Crank Mast
A Swan Neck mast has a double bend it. Using a 6’ mast as an example the first bend will be approximately 1’ from the end of the mast at about 45 degrees, the second bend will be approx. a further 1’ which will straighten the mast upright leaving the remaining 4’ to extend above the obstruction.The mast of course can actually be installed the other way up with the 1’straight section at the top but this is far less common.
Double Crank Mast
A double crank mast is very similar to the Swan Neck mast except that it will allow you to extend much further away from the fixing bracket allowing you to clear deep soffits etc. Using a 6’ mast again as an example, the first bend will be approx 1’ into the pole at approx 45 degrees. The next bend will then be about 1’ before the end of the mast. This creates a far bigger stand off than the Swan Neck mast.
Sky Style Crank Pole
There is another type of mast commonly used by Sky for satellite dish installations where the dish needs to be installed to clear an obstruction. Typically when the dish needs to be installed on a wall not south facing, like a north facing wall where the dish need to look over the building to get line of sight to the satellites in space.
I never use these masts and I would always try to use T and K wall brackets and a straight mast for a much stronger fixing. The mast itself is painted steel so it would be prone to rusting like the satellite dish itself.
The main difference and the reason I included it in this blog is because the mast cranks at 90 degrees in two positions meaning that it can fit in a smaller space so may serve a purpose. The mast is usually fixed to the wall with 2 x split brackets.
A J mast is a mast in the shape of a J, believe it or not.These are usually of a 1” diameter (the only 1” mast that I would use) and a single bend which forms the J. These are usually 3’ high with approx. 1’ extension away from the fixing bracket. J masts are only suitable for light loads when installed outside. I most commonly use these for loft aerial installations where there is no wind-loading on the aerial and aerial pole. The only real time I would use these outside would be to mount onto a fascia where there is a limited fixing space. Even then I would try and use a 6” wall bracket and a straight mast if it fits as this would provide a stronger fixing. J masts are usually fixed to the wall with a Heavy Duty Fascia Bracket or Swivel Bracket in a loft.
This is a quite clever design and can speed up with installation time with installing TV aerials in lofts. It is simply a straight mast with a screw type fixing to which you bang into a loft beam/ strut and twist to fix into position, no tools required. Personally, I prefer a mast and swivel bracket for loft installations but I can see why these may have some appeal.
TV/ Radio Aerial, Antenna & Mast Questions?
If you have any questions, please post them in the blog comment section below. As I said at the beginning of this blog the natural partner to it is our previous blog on wall brackets so please check that out after you’re done here. Please DO NOT CALL OUR TELEPHONE LINES. These are reserved for CUSTOMERS ONLY and we only serve a small area in the South East of the UK. Please also DO NOT FILL OUT THE WEBSITE CONTACT FORMS OR E-MAIL as you will either not receive a response or you will receive a response asking you to post your questions in the blog comment section of the blog you read. Providing you post your question below and are patient with for a response I will help out where I can.
Until next time,
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