UHF Satcom Antenna from Antennas.us - Any Experience? Opinions?

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paulears

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That's of course your choice, but my personal view is that the needs of an amateur are totally different and scanners often have better usability. I've been tendering for a commercial marine project. The equipment that meets the specification is 19" rack mounting, has dual power supplies with auto changeover. The changeover also switches a coax relay to swap to an alternative antenna. It has to run 24/7/365 with no chance of failure. For the operators it offers ZERO advantages, and in fact, two standard class A marine vessel sets with power supplies would offer better reliability and heaps more useful features that the industrial units have. Two of these radios would cost around 800 UKP. The commercial grade ones in the tender are 4000 each. I can provide you certified aircraft radios, or a leisure radio. There is a difference. Better filtering so with the new 8.333KHz spacing, a channel next door will not bleed so much.

I commend you idea, but the equipment grade you are purchasing is ridiculously over specified and probably poorer for the typical scanner user's needs - which are VERY different from the military or Federal users needs.

I cannot speak for the US situation, but the old Radio Authority in the UK used Racal receivers in their mobiles until the first AoR scanners appeared and then they could afford multiples of these rather than just one military grade receiver. Now with SDR radios, monitoring equipment is vastly different from what you are describing. Your requirement for mimicry is admirable - but thank goodness you have surplus funds, because for most of us - we simply do not have access to exotic radios. I appreciate this is your focus of the hobby - but while I have always wanted a new Range Rover, sadly, it isn't going to happen. My wife believes my 'need' for one is foolish. She may be right.

If I wanted to listen to satcom, I'd be looking at cleverer antennas than a zero gain hemispherical . With your access to funds I'd have thought a rotator with rotation and elevation and circular polarised log-periodic or helical would be where the fun would be. I'd pay for gain. I'd certainly consider a commercial antenna bad value for money. I'd also by a Harris - and I even know which one, like I know the Range Rover I'll never have.
 

Merovingian

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I'm amazed how a hobbiest would consider a commercial grade antenna for a leisure project like this. Do you need the strength, reliability and super construction? The ham satellite people have been doing this for a very long time - starting with the UHF slow scan satellites and weather stuff, and if you google bowties and turnstile antennas you'll find them totally DIY and dirt cheap. In essence a normal dipole has a broadly donut shaped capture area so once you get above 45 degrees or so, the performance drops off to virtually nothing overhead, so you mount the dipole horizontal, which gives a figure 8 pattern, with decent coverage upwards. Add another at right angles and it fills in the side nulls. They work great for satellites. Hams love the diamond X-30s and X-50s - less than $100. The commercial antennas that are usually single band and virtually the same performance can be 500+. The fibreglass is thicker. The parts will probably be stainless rather than aluminium, the SO239 will be an N and the thickness of mounting tubes 3-4mm thick wall tube rather than .75 or 1mm Ali. Performance wise - it means the Jaybeam commercial UHF one on my repeater is getting close to 30 years old now and still going strong.

I think along similar lines to prcguy when it comes to antennas. I don't need the battle hardened durability of this type of antenna but it is nice to have. I prefer to spend my time using the equipment rather than building it. If I were a skilled machinist with $50,000 worth of machining tools (lathes, mills, ect.) and could precisely make great works of art with metal and had the knowledge and test equipment to test and optimize the antennas I make then I would prefer to make my own. I'm a bit of a perfectionist when it comes to things I make, I can't live up to my own standards when it comes to precision fabrication so I don't usually attempt it, unless it is something simple. As it is, my tools amount to a dremel tool, a battery powered hand drill, a crappy drill press, a tape measure and the garage floor as a workbench. I have considered getting a bench top mill and a small lathe but I currently have no place to put them and I have never used them before so everything will be a struggle for a while.

I am still tempted to build prcguy's satcom antenna, I will keep thinking about that but I may end up buying one anyway. If I buy it at least I know it is built correctly and tested thoroughly. The only concern would be the sidelobes pointing straight up vs prcguy's pointing at the satellites.
 

prcguy

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I'll set the record straight here that I don't just go out and buy new military or aircraft or similar radios new. I've been collecting these for most of my life and usually pick them up for a fraction of even their used surplus value. My goal is to pay much less than the going rate so if I decide to sell someday I can make a profit to fund other radios.

This has worked out well for me over the last 40yrs or so where its not uncommon to buy a small lot of modern high end military surplus radios and sell off the extras, which not only paid for the one I keep but might leave an extra $5k or more in my pocket for when the next deal comes up. It sounds like a business but its not, I've just been lucky to have learned enough about this facet of the hobby and have met countless other collectors and can recognized a great deal and act on it instantly before someone else grabs it.

At some point most of the high end radios and antennas used by our militaries get surplused, same with current new multiband commercial gear and someone is going to be there when it hits the market cheap. I try my best to be the first one in line when that happens.

BTW, the X-wing UHF satcom project mentioned here is not a zero gain hemispherical, I forget the exact gain but its over 5dBic with the gain lobe optimized for the US or UK with the antenna sitting flat on the ground or roof and no pointing is needed. I have, or had one of the largest private collections of military UHF satcom antennas I've ever seen and when I want to listen to some UHF satcom I reach for my home made X-wing.


That's of course your choice, but my personal view is that the needs of an amateur are totally different and scanners often have better usability. I've been tendering for a commercial marine project. The equipment that meets the specification is 19" rack mounting, has dual power supplies with auto changeover. The changeover also switches a coax relay to swap to an alternative antenna. It has to run 24/7/365 with no chance of failure. For the operators it offers ZERO advantages, and in fact, two standard class A marine vessel sets with power supplies would offer better reliability and heaps more useful features that the industrial units have. Two of these radios would cost around 800 UKP. The commercial grade ones in the tender are 4000 each. I can provide you certified aircraft radios, or a leisure radio. There is a difference. Better filtering so with the new 8.333KHz spacing, a channel next door will not bleed so much.

I commend you idea, but the equipment grade you are purchasing is ridiculously over specified and probably poorer for the typical scanner user's needs - which are VERY different from the military or Federal users needs.

I cannot speak for the US situation, but the old Radio Authority in the UK used Racal receivers in their mobiles until the first AoR scanners appeared and then they could afford multiples of these rather than just one military grade receiver. Now with SDR radios, monitoring equipment is vastly different from what you are describing. Your requirement for mimicry is admirable - but thank goodness you have surplus funds, because for most of us - we simply do not have access to exotic radios. I appreciate this is your focus of the hobby - but while I have always wanted a new Range Rover, sadly, it isn't going to happen. My wife believes my 'need' for one is foolish. She may be right.

If I wanted to listen to satcom, I'd be looking at cleverer antennas than a zero gain hemispherical . With your access to funds I'd have thought a rotator with rotation and elevation and circular polarised log-periodic or helical would be where the fun would be. I'd pay for gain. I'd certainly consider a commercial antenna bad value for money. I'd also by a Harris - and I even know which one, like I know the Range Rover I'll never have.
 

iMONITOR

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Yeah, they are pretty high. I want something decent quality and semi compact like they are offering but I don't really need something combat hardened that weighs a ton either. It would be nice if someone made a light duty version of their antennas.

I agree. I think a lot of companies are missing a huge market if they made hobby grade affordable dual-band antennas for aircraft and antennas for satcom. These antennas aren't magic, they don't contain alien technology. They're very simple and probably could be mass produced for a vary low cost.
 

Merovingian

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I agree. I think a lot of companies are missing a huge market if they made hobby grade affordable dual-band antennas for aircraft and antennas for satcom. These antennas aren't magic, they don't contain alien technology. They're very simple and probably could be mass produced for a vary low cost.

I also want to put up an antenna for receiving NOAA APT transmissions. As I understand it one of the best antennas for that is a QFH antenna. They seem to be much more difficult to build than prcguy's design so I would obviously want a professionally made antenna of that type so I know it is done right. After much research I was surprised to find that Diamond makes one. Theirs is expensive compared to most of their others but not terribly expensive like $900 or $7,000 and I would gladly pay their higher price for a decent professionally made antenna like they make. It would be nice if someone could take prcguy's design and make that professionally, either ground or pole mount options, even a kit, everything is ready I just have to put it together, like Ikea furnature.
 

prcguy

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I think the audience for UHF satcom reception is very small and not enough for anyone to make and sell hobby based antenna and make a living. The military jobs have a 90deg 3dB hybrid coupler inside that cost upwards of a few hundred $$ not counting the high power terminating chip resistor and precision cut phasing lines. Then you have a trail of accountability and inspections along each and every phase of manufacturing, which is what drives the prices up. A hobby version would have to be made of consumer grade components with a clever design that is easy to manufacture.

In the end a hobby UHF satcom antenna would have to cost at least few hundred $$ and I think there are plenty of military surplus versions that would or should sell for less than that.

I agree. I think a lot of companies are missing a huge market if they made hobby grade affordable dual-band antennas for aircraft and antennas for satcom. These antennas aren't magic, they don't contain alien technology. They're very simple and probably could be mass produced for a vary low cost.
 

paulears

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You are confusing price with construction.Commercial antennas sell in low numbers, so this causes, or at least contributes the the crazy pricing. They are NOT value for money, and often perform no better than the hobby/amateur products. Aviation is a very good example. An aviation dipole is no way worth what they cost. A marine VHF antenna is virtually the same design and cheaper, and some of the ham ones are a tenth of the cost for again - the same design. Confusing cost with quality is understandable. The notion that a bit of metal in the sky can be worth $900 is simply ridiculous. What would be 'cost effective'? Obviously it's up to the individual, but a perfectly decent antenna can be found for most uses for less than $200. Amateur products are not in general less reliable - I have the discone I bought in 1980 and it is perfectly serviceable. I've seen others made from lower grade Ali, and they corrode badly and crumble in the salty sea air here. The commercial antennas are just overbuilt for non arduous usage. A military grade antenna is maybe three times the weight, twenty times the cost and designed for amazingly hard use. Hard use is not sitting on a pole in the sunshine. There is no Kudos in owning a commercial antenna - only you will know. I'd happily sell them, but nobody would buy them. Satcom antenna sales are tiny, and most users need decent products, so even basic ones are built to sensible standards - expeditions, sea going vessels - use them for safety, so the basic sat com gear is already tough. Mil spec merely means a tank can run over it - that is surely irrelevant in a non-military environment.
 

Merovingian

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See post # 11 in this thread for the instructions. MT magazine UHF Satcom antenna project

I've been testing to see if I want to build the antenna so I have been looking for the parts to see what it would cost.

Quick question. I was looking at the instructions for your antenna, the parts list in part one states:

6 8-32 X 1/2” Phillips screws, stainless steel
6 8-32 hex nuts, stainless steel

In part two you state:

"Temporarily mount the elements using 6-32 hardware placing the screw through the element and pipe cap with nuts on the backside of the cap."

Was that supposed to be 8-32 hardware? Or should the parts list be 6-32 hardware? Maybe it doesn't matter? Just wondering.

Also, I have been searching for the F connectors you say needs to be at least 1/2" long. I have been having trouble finding something long, most places don't give a length. I did find this:


Would that work just as well?

Thanks
 

prcguy

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What idiot wrote that up? I'll have to dig out the prototype and check, give me a few hours.

I've been testing to see if I want to build the antenna so I have been looking for the parts to see what it would cost.

Quick question. I was looking at the instructions for your antenna, the parts list in part one states:

6 8-32 X 1/2” Phillips screws, stainless steel
6 8-32 hex nuts, stainless steel

In part two you state:

"Temporarily mount the elements using 6-32 hardware placing the screw through the element and pipe cap with nuts on the backside of the cap."

Was that supposed to be 8-32 hardware? Or should the parts list be 6-32 hardware? Maybe it doesn't matter? Just wondering.

Also, I have been searching for the F connectors you say needs to be at least 1/2" long. I have been having trouble finding something long, most places don't give a length. I did find this:


Would that work just as well?

Thanks
 
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