@KellyJay
What does designed communications equipment mean?
Communications was my job for quite a while, ever hear of dual space diversity microwave communications? I worked on what was known as the TRC 90, ever hear of that style of links?
@KellyJay
What gain numbers did you aim for in the design of cell tower antennas?
I assume it wants to be mostly a pancake shaped radiation pattern which would seem to me to maximize cell phone range, but what kind of gain is desired for the antennas?
@KellyJay
What kind of power shoots out of cell towers? My TRC 90 used a 1500 watt amp at 5 gigahertz.
If I have it right, the antenna's on cell towers have a really high gain and therefore a narrow physical band, Making the RF pattern like a pancake, low to the ground, horizontal for maximum gain so what gain numbers are bandied about for cell phone tower antennas?
As a ham we are lucky to get 10 DB out of an antenna and would love 20DB. so what about cell towers?
@sonhouse saidYou know far more about that than me. We test them against each other in-house so antennas are not part of processing.
@KellyJay
What kind of power shoots out of cell towers? My TRC 90 used a 1500 watt amp at 5 gigahertz.
If I have it right, the antenna's on cell towers have a really high gain and therefore a narrow physical band, Making the RF pattern like a pancake, low to the ground, horizontal for maximum gain so what gain numbers are bandied about for cell phone tower antennas?
As a ham we are lucky to get 10 DB out of an antenna and would love 20DB. so what about cell towers?
@KellyJay
That doesn't sound right, I remember an engineer talking about what became of space diversity troposcatter microwave communications link, which used two separate dish antennas about 10 meters apart which allowed relatively short range links to about 200 miles away but the next generation was called FREQUENCY diversity troposcatter links where there were some 21 separate microwave frequencies and used only one antenna and a continuous scan of all those frequency, and within milliseconds there would be a decision about which frequency had the best signal so both units switched to that new frequency which maybe would hold for a second or so and then switch from say channel 20 to channel 3 and so forth.
BTW, that frequency shifting idea was patented by an actress named Hedy Lamarr. She was a real genius, worked that out with a musician named George Antheil in WW2, when she heard about German frequency jamming, she came up with the idea of frequency hopping so the jammers would not know what frequency a transmitter would go to next.
Anyway the engineer who was developing that then new technology said to me, we engineers will FIGHT for even 1/10th of one db gain which of course increases the reliability of the system as a whole.
That technology is not used on cell phone towers but the microwave engineers HAVE to know exactly how many db of gain each antenna has, for instance, if a single antenna has a gain of say 4 db, and a second one is added, phased into the system, it goes up 3 db so the two together has a 7 db gain and a correspondingly flatter pancake like radiation pattern, and those numbers I just picked out of a hat because it is very easy to get high gains at 5 ghz and above frequencies.
My guess and it is admittedly a guess, they would have some TWENTY db of gain, or an increase in effective power out of 100 times, so in the resultant beam, a one watt transmitter would feel like a 100 watt transmitter but a much narrower beamwidth, like a pancake which is the tradeoff when you build antennas, you can't have a physically wider beam when you go for higher gain, the more the gain the narrow the beam width is.
So db gain figures HAVE to be considered and designed for in order to get the max range with cell phone pumping out maybe a tenth of a watt of RF.
@sonhouse saidI was a radioman antenna in the Navy in the early 70s, so I had to study a little about antennae as part of my promotions up the ranks, the different types, what they did, and how they worked, but that was a while ago. We would change out what antennae was connected to radios/communication systems we were using to send the signals where we wanted them according to the signal we wanted to produce, before computers did that, that was quite fun.
@KellyJay
That doesn't sound right, I remember an engineer talking about what became of space diversity troposcatter microwave communications link, which used two separate dish antennas about 10 meters apart which allowed relatively short range links to about 200 miles away but the next generation was called FREQUENCY diversity troposcatter links where there were some 21 se ...[text shortened]... esigned for in order to get the max range with cell phone pumping out maybe a tenth of a watt of RF.
Where I work they spend a lot of time testing these radios, the radio is still one part of the whole, and like many specified functionally complex pieces of a whole, they know what is going to occur before they connect it with the rest.
When they are building them they know the typographical areas where the radios are going to be placed, there are maps of the area, letting them know what the signals are going to have to contend with, this includes exactly where the mates are going to be placed. These typically always come in at least a pair sometimes more networked together, they take into account what is required to get the signals from A to B is always considered.
@KellyJay
Yep, but that is mostly been taken over by sat comm links, which uses UHF frequencies, high Ghz range which penetrates the atmosphere unlike the stuff around say 10 Mhz, so all our former microwave skills are mostly gone now except for cell phone towers and emergency communications and of course my ham stuff.
Did you ever get a ham license? I got my first one when I was 14. Now have the top license, amateur extra.
@sonhouse saidNo never did, but since I am about to retire I am thinking about getting involved in several things. Otherwise my wife will go nuts having me around all the time.
@KellyJay
Yep, but that is mostly been taken over by sat comm links, which uses UHF frequencies, high Ghz range which penetrates the atmosphere unlike the stuff around say 10 Mhz, so all our former microwave skills are mostly gone now except for cell phone towers and emergency communications and of course my ham stuff.
Did you ever get a ham license? I got my first one when I was 14. Now have the top license, amateur extra.
Thinking about getting licensed to fly drones as a side business checking out aerial views for real-estate properties, writing a sequel to my book, taking chess more seriously. Lots of possibilities right now. Mainly I am just grateful spending 3 hours a day on a busy interstate is coming to an end.
@KellyJay
Been there, done that, long commute thing, from my town of Slatington Pa to South Plainfield NJ, 160 mile round trip from 2001 to 2022, and that with two different companies that happened to be one block apart🙂
The ham test doesn't have code any more, only tech questions and they are not that hard.
I made a 'fan dipole' antenna from scratch and I have an antenna analyzer called Rig Expert, mine goes up to 600 megs, plenty good enough for me, my top band I use is 440 Mhz band.
So It just fell down and I have to find a way to get the rope over some 50 foot high trees, I tried a cheap drone but I could never get it stable enough to control, it would just go off on its own and crash a half mile away🙂
then used slingshots but not strong enough, then built a potato gun which I charged up to about 70 PSI and that got a projectile over the trees which allowed me to get SOMETHING going ham wise.
But my rig expert which BTW, is made in Ukraine! and it informed me what I thought was the 40 meter part, was not 7 megs but 9 megs which shows that part of the fan was too short so I have work to do to get it in resonance.