Community discussions

 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Microstrip (flat panel) versus eliptical (disk) antenas?

Wed Apr 06, 2016 2:53 pm

I raised similar sort of question years ago but with new insights (maybe) and more experiences and wider availability of both types maybe some more conclusive statements can be made?

If given a same gain in dBi, which antenna is better? A microstrip one, or a eliptical (dish) one?
And now also; under heavy congested spectrum circumstances.

Say an 25dBi (Dynadish?) or 24dBi (QRT) antenna points in a direction for a backhaul connection but some other antenna is sending wifi radio wave in a close, or the same, frequency band from under and angle of lets say 25, or 45, or 60 degrees?

When we have a metal dish antenna, basically it shields the horn off from signals coming from behind up to an side angle to where the horn itself directly becomes visible from the side. This can be made better by using a radome shield (Like Jirious uses or you can buy separate from many dish antenna vendors Mikrotik included).
But a plastic dish like the Dynadish has, signals strong enough will just penetrate through the dish and still hit the cone?

In case the horn directly comes visible from outside the dish's sphere how sustainable is it to pick up unwanted signals?
(The horn head is also a deflector, so it should only pick up signal coming from the sphere? This last puts a plastic dish is disadvantage compared to a metal one since the plastic one still allows radio energy from behind to penetrate and hit the dome head?)

Now look at a QRT. Basically all signals coming from an angle bigger than 90 degrees (so from the side to the back) are shielded off by the metal back plate of the microstrip print.
But signals coming from anywhere between 90 up to 5 degrees (so still outside its working beam) will still hit the microstrip.

So, both type of antennas will be picking up signals from unwanted directions. But which type is best in reducing the signal level from different angle than the projected one?

Off course I know its all about the S/N ratio between the signal to use and surrounding (and background) signals (or noise) but some times radios from 3rd party are hitting my antennas with signal levels almost the same as my own projected signal. So I have to use shields or randome covers and sometimes relocate antennas behind or around the corner of a building. But I am also developing more and more the feeling dish antenna's are a better choice than microstrip to avoid unwanted 'noise'.

Any intakes in this?
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
InoX
Forum Guru
Forum Guru
Posts: 1963
Joined: Tue Jan 09, 2007 6:44 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Wed Apr 06, 2016 6:06 pm

A dish antenna is better, but a metal one. Look at antenna patterns.
http://i.mt.lv/routerboard/files/mANT30 ... 124123.pdf
http://i.mt.lv/routerboard/files/qrt5-p ... 125548.pdf
http://i.mt.lv/routerboard/files/DynaDi ... 104141.pdf
I wouldn't install anything but mANT30 in base.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Thu Apr 07, 2016 4:54 pm

A dish antenna is better, but a metal one. Look at antenna patterns.
http://i.mt.lv/routerboard/files/mANT30 ... 124123.pdf
http://i.mt.lv/routerboard/files/qrt5-p ... 125548.pdf
http://i.mt.lv/routerboard/files/DynaDi ... 104141.pdf
I wouldn't install anything but mANT30 in base.
Well, a mANT30 is almost twice as big as an QRT and combined with a netmetal also 50% more expensive.
The bigger the dish, the better its focus the better the noise rejection from unwanted angles.
So its not fair to compare this one with the two others. If we would have a 30dBi microstrip antenna then we could compare.....

The comparison between the QRT and the Dynadish is better but we see not too much difference. They both have significant side lobs, the Dyna more homogenous, so the differences can be in the VSWR and F/B ratio and Port2Port and Cross Polarisation isolation. However, info for the Dyno is very limited. The fact it has a plastic dish plus the diagrams don't give me lots of confidence in this device.

So comparisons should be made between metal dish and micro strip of the same dBi's.
Another problem often seen is that althoug manufacturers do at times supply specs and diagrams, the latter are not always based on the same scale or do have figures in them at all!
I can draw two diagrams for one and the same antenna where in one the impression can be its a good antenna where the other makes the impression it is not. (Ubnt for instance always uses the -6dB line to give a sector of directional its working angle. Comparing a 90º sector of them with a 90º of another brand is actually comparing a 60º unbt with an 90º other. Apples and pears.....)

I am also wondering how much the shields would actually help in reducing unwanted signals. (The ones you'll find for the range of SXT's, SEXTANT, QRT etc.)
Because of the metal they probably do reduce the level of noise coming from behind up to an 90º angle.
But what about the 90º to 30 or 20 or 10º angle? I presume here they do nothing since the signal is not blocked by the shield. So what if these shield should be made much longer so only the forward beam can leave and the rest is blocked.
But now the side lobes from the radio bounce against the sides too. Would this make things worse or better?

Basically the best antenna's imho would be metal dishes of the highest possible gain. But to make a 500 meter link with a 34dBi dish would be a bit ridiculous!
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
ste
Forum Guru
Forum Guru
Posts: 1813
Joined: Sun Feb 13, 2005 11:21 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Thu Apr 07, 2016 6:33 pm

A dish antenna is better, but a metal one. Look at antenna patterns.
http://i.mt.lv/routerboard/files/mANT30 ... 124123.pdf
http://i.mt.lv/routerboard/files/qrt5-p ... 125548.pdf
http://i.mt.lv/routerboard/files/DynaDi ... 104141.pdf
I wouldn't install anything but mANT30 in base.
Well, a mANT30 is almost twice as big as an QRT and combined with a netmetal also 50% more expensive.
The bigger the dish, the better its focus the better the noise rejection from unwanted angles.
So its not fair to compare this one with the two others. If we would have a 30dBi microstrip antenna then we could compare.....

The comparison between the QRT and the Dynadish is better but we see not too much difference. They both have significant side lobs, the Dyna more homogenous, so the differences can be in the VSWR and F/B ratio and Port2Port and Cross Polarisation isolation. However, info for the Dyno is very limited. The fact it has a plastic dish plus the diagrams don't give me lots of confidence in this device.

So comparisons should be made between metal dish and micro strip of the same dBi's.
Another problem often seen is that althoug manufacturers do at times supply specs and diagrams, the latter are not always based on the same scale or do have figures in them at all!
I can draw two diagrams for one and the same antenna where in one the impression can be its a good antenna where the other makes the impression it is not. (Ubnt for instance always uses the -6dB line to give a sector of directional its working angle. Comparing a 90º sector of them with a 90º of another brand is actually comparing a 60º unbt with an 90º other. Apples and pears.....)

I am also wondering how much the shields would actually help in reducing unwanted signals. (The ones you'll find for the range of SXT's, SEXTANT, QRT etc.)
Because of the metal they probably do reduce the level of noise coming from behind up to an 90º angle.
But what about the 90º to 30 or 20 or 10º angle? I presume here they do nothing since the signal is not blocked by the shield. So what if these shield should be made much longer so only the forward beam can leave and the rest is blocked.
But now the side lobes from the radio bounce against the sides too. Would this make things worse or better?

Basically the best antenna's imho would be metal dishes of the highest possible gain. But to make a 500 meter link with a 34dBi dish would be a bit ridiculous!
The Antenna has to match the usage case. For small distances micro-strip is ok. At higher distances the metal dishes work better. With licensed links you never use micro-strip. There are only dishes as it does not make sense to combine an expensive radio with a cheap antenna.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Fri Apr 08, 2016 6:17 pm

The Antenna has to match the usage case. For small distances micro-strip is ok. At higher distances the metal dishes work better. With licensed links you never use micro-strip. There are only dishes as it does not make sense to combine an expensive radio with a cheap antenna.
Off course.
But it wasn't me if I didn't want a discussion.... :D

We have some links doing 100, 150, 300 and 400 meters in an area where are 5 AP's active and 5 big backhauls leave to remote locations.
At the same time from some 1,5 km we have one other provider pointing his AP directly towards us and one of his backhauls (also 5Ghz) again overshoots our towers.
Then we have at least 2 other providers that had pointed their AP's directly to our region.

In other words, if I open a scan on one of my towers each available frequency in the 5Ghz band is used and on a 8dBi omni we have signals coming is in any range from -45 or weaker...
Meaning that no matter how much we puzzle to find relative free bands, some of our smaller backhauls (SXT's or SXT-HG's) are that much 'open' in their beam it is unavoidable to have these picking up signals from not too far away transmitters, sometimes even 5, 10 or 20Mhz away in their centre frequencies.)

Hence I works as much as possible with shielded and narrow beam antennas. But it is clear to anyone; to cross a street two 25dBi or 30dBi dishes would be ridiculous! (cable is not an option)
Working on very short distances with high gain (narrow beam) antennas would bring another disadvantage; over powering the receiver circuits of the 'other side'.
Off course you can lower the output of the transmitters, but I have noticed in the past (and actually that's been confirmed by one of MT) that when radios are set below 8-10dBm they become unstable.
I already have some units set to such levels. We have several backhauls with NetMetals that run on 8 or 10dBm output and still deliver -40 at the other end.....

For us it would be so nice to have some antennas that would have a really very narrow beam compared to low gain. But the techs tell me that both in dish as in strip antennas the higher the gain, the narrower the beam. There would be no escape from such law of maths..... So if I want a small low gain antenna, it is inevitable it will pick up signals from everywhere forward-around him......

So I am going to gamble no on a new line of 60Ghz units hitting the market. 3-4 times more expensive as a Netmetal based links, but at least not thousands of euros anymore for other alternatives....
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
User avatar
docmarius
Forum Guru
Forum Guru
Posts: 1219
Joined: Sat Nov 06, 2010 12:04 pm
Location: Timisoara, Romania
Contact:

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sat Apr 09, 2016 7:14 pm

The statement that microstrip antennes will receive anything that can hit the front surface is wrong.

The phasing of the microstrip interlink will cancel out or significantly attenuate signals coming from directions greater than a certain angle form the antenna axis, those 5 degrees cited in the first post.

So actually an antenna with the same gain and radiation pattern will behave the same way, no matter of its construction technique (metal reflector, microstrip, horn, slit, fractal, yagi, whatever...), since those 2 elements describe its radiation and receiving behavior completely (receiving and transmitting being mathematically and physically equivalent).
Torturing CCR1009-7G-1C-1S+, RB450G, RB750GL, RB951G-2HnD, RB960PGS, RB260GSP, OmniTIK 5HnD and NetMetal 922UAGS-5HPacD + R11e-5HnD in my home network.
 
n21roadie
Forum Guru
Forum Guru
Posts: 1889
Joined: Fri Aug 07, 2009 10:36 pm
Location: Limerick,Ireland

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sat Apr 09, 2016 8:36 pm

The statement that microstrip antennes will receive anything that can hit the front surface is wrong.

The phasing of the microstrip interlink will cancel out or significantly attenuate signals coming from directions greater than a certain angle form the antenna axis, those 5 degrees cited in the first post.

So actually an antenna with the same gain and radiation pattern will behave the same way, no matter of its construction technique (metal reflector, microstrip, horn, slit, fractal, yagi, whatever...), since those 2 elements describe its radiation and receiving behavior completely (receiving and transmitting being mathematically and physically equivalent).
If antenna's would cancel or significantly attenuate signals coming from directions greater than a certain angle, we wouldn't have to employ RF screening to reduce co-location interference ?
N21roadie,
Network 100% MT for Now?
 
n21roadie
Forum Guru
Forum Guru
Posts: 1889
Joined: Fri Aug 07, 2009 10:36 pm
Location: Limerick,Ireland

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sat Apr 09, 2016 9:32 pm

................................

So I am going to gamble no on a new line of 60Ghz units hitting the market. 3-4 times more expensive as a Netmetal based links, but at least not thousands of euros anymore for other alternatives....
I have only seen a 35cm dish 60Ghz unit is there larger available?
N21roadie,
Network 100% MT for Now?
 
User avatar
docmarius
Forum Guru
Forum Guru
Posts: 1219
Joined: Sat Nov 06, 2010 12:04 pm
Location: Timisoara, Romania
Contact:

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sun Apr 10, 2016 1:01 am

If antenna's would cancel or significantly attenuate signals coming from directions greater than a certain angle, we wouldn't have to employ RF screening to reduce co-location interference ?
By employing RF screening, you actually change the antenna's radiation pattern. I was talking about 2 antennas with similar radiation patterns, and about the fact that the build technology is not the decisive factor.
You can build high performance microstrip antennas, like the ones used in aircraft radar, with a very small beam width, they are just to expensive for general use, so for high gains, parabolic reflectors are the economic choice.
You just can not compare a 2 degree parabolic antenna with a 10 degree flat panel, even if the gains are similar.
Torturing CCR1009-7G-1C-1S+, RB450G, RB750GL, RB951G-2HnD, RB960PGS, RB260GSP, OmniTIK 5HnD and NetMetal 922UAGS-5HPacD + R11e-5HnD in my home network.
 
pe1chl
Forum Guru
Forum Guru
Posts: 5920
Joined: Mon Jun 08, 2015 12:09 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sun Apr 10, 2016 12:31 pm

You just can not compare a 2 degree parabolic antenna with a 10 degree flat panel, even if the gains are similar.
But you normally will not find those, because gain is the inverse of beamwidth.
When the sidelobes are reasonably down relative to the main lobe, and when the manufacturer is honest (this is
often not true in the antenna business!), you can directly translate the beamwidth to the gain and vice-versa.

The only variable is the characteristics of the sidelobes. These are different for focussing antennas like the dish
and phased-array antennas like the flat panel. And for a dish they can be changed by adding the shroud that limits
the overspill from the feed over the edges of the dish.
 
0ldman
Forum Guru
Forum Guru
Posts: 1446
Joined: Thu Jul 27, 2006 5:01 am

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sun Apr 10, 2016 7:56 pm

As I mentioned on the other thread (MT distance), panels seem to work best when the shot is less than ideal, shooting through trees, fresnel obstructions, etc.
Dishes are more focused, better front to back ratios, etc.

Each serves a purpose.

In my experience, I prefer panels on clients and dishes in the air. I have less trouble out of clients using panels, especially since MIMO has become a thing.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 1:48 am

The statement that microstrip antennes will receive anything that can hit the front surface is wrong.

The phasing of the microstrip interlink will cancel out or significantly attenuate signals coming from directions greater than a certain angle form the antenna axis, those 5 degrees cited in the first post.

So actually an antenna with the same gain and radiation pattern will behave the same way, no matter of its construction technique (metal reflector, microstrip, horn, slit, fractal, yagi, whatever...), since those 2 elements describe its radiation and receiving behavior completely (receiving and transmitting being mathematically and physically equivalent).
Well, its clear that if two different antennas would produce the same radiation pattern in the test bench, they are the same in characteristics... But so far I haven't seen that yet.... they sometimes come close.

Apart from that, its about exactly what you write; "significantly attenuate". I've had occasions where a SXT wat getting a signal from no so far, but under 50º angle, 3rd party AP that was actually stronger than the signal this unit was getting from my own AP! We are talking -40 to -50 ranges!. Even trying to find other frequencies to work in didn't help. In the end we lost the client because we couldn't supply him a stable connection. Other CPE units 50 to hundreds or more meters away and in different angles towards this 3rd party AP worked fine and have no issues.
On this specific client we swapped the SXT 3 times, we replaced cables and plus several times and we could only give him some reasonable connection with 5Mhz channel. But that was not good enough for the rest of the clients so in the end we choose we couldn't help him....

Up to today I'm wondering if a metal dish antenna with maybe extra radome shield or something similar would have helped that situation...
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 1:50 am

................................

So I am going to gamble no on a new line of 60Ghz units hitting the market. 3-4 times more expensive as a Netmetal based links, but at least not thousands of euros anymore for other alternatives....
I have only seen a 35cm dish 60Ghz unit is there larger available?
Why would you want larger? Smaller is one of the advantages for 60Ghz.....
http://www.ignitenet.com/products/metrolinq/
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 2:01 am

You just can not compare a 2 degree parabolic antenna with a 10 degree flat panel, even if the gains are similar.
But you normally will not find those, because gain is the inverse of beamwidth.
When the sidelobes are reasonably down relative to the main lobe, and when the manufacturer is honest (this is
often not true in the antenna business!), you can directly translate the beamwidth to the gain and vice-versa.

The only variable is the characteristics of the sidelobes. These are different for focussing antennas like the dish
and phased-array antennas like the flat panel. And for a dish they can be changed by adding the shroud that limits
the overspill from the feed over the edges of the dish.
So, what is it they do with these yagi antennas?
2.4 GHz 15 dBi Yagi Antenna_T24150Y13602l.jpg
They are 2,4Ghz but the energy patterns aren't that much different?

At times you need to bridge only some 10, 50 or 100 meters with 5Ghz where a big antenna would way to powerful but a low gain antenna picks a lot of noise. (and probably still is too powerful)

Actually I need a 1 or 2dBm radio coupled to a 5º or 10º beam antenna that is not bigger than lets say an SXT. It looks like in 5Ghz it is just not possible.
You do not have the required permissions to view the files attached to this post.
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
pe1chl
Forum Guru
Forum Guru
Posts: 5920
Joined: Mon Jun 08, 2015 12:09 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 11:00 am

Yagi antennas usually have more sidelobes than dish antennas. But they are well usable.

Please note that antennas have to work within physical limits. Anything that you see advertised that
appears to be much better than average is usually a fraud. And there are lots of fraudsters in the
antenna business, because it is so easy to put specs on the box that nobody will verify in practice,
and are often compared by customers and used as a direct criterion for selection (e.g. 1 dB more).

Antenna gain, for example, is often inflated beyond what the antenna really does. But an indication
that something is wrong can already been found from the comparison of beamwidth and gain.

Antenna gain is achieved by bundling the emission. See it as a lightbulb vs a torch. When you light
a bulb in free space it will spread the light all around, when you put the same bulb in a torch with
a reflector, the light is sent in one direction and the spot is brighter than the same area as lit by the
free bulb. The bulb does not have more power, but its light is bundled at a small area.

You can easily see that the narrower the beam, the stronger this effect. Narrower beam is more gain.
And you can also see that it is impossible to make a torch mirror that will emit a wide beam and at
the same time make it as bright as a narrow beam.

With an antenna, exactly the same mechanism is being used (light and radio waves are the same thing!).

There are simple formulas that calculate the theoretical maximal gain of a dish antenna at a certain frequency:

gain = (pi * d / wavelength)^2

d is the diameter of the dish, so for a 30cm dish at 5.6 GHz (wavelength = 300/5600):

gain = (pi * 0.3 / (300/5600))^2 = 309.5 = 24.9 dB

Any really manufactured antenna will have less gain than this, due to imperfect lighting by the feed and
other losses. So now you know that the antenna manufacturer that claims 25dB gain from a 30cm dish
is a fraudster. 22dB is a more realistic figure for such a dish.

The beamwidth of the perfect antenna is inversely proportional to the gain. In fact the gain is achieved by
lighting a small portion of the complete sphere illuminated by the isotropic radiator, so the portion that
is lit is just the 1/gain portion of the sphere.
What makes it a bit more complicated is that the beam not necessarily has a circular shape. For antennas
like a dish with feed it typically has, but it is possible to construct an antenna that has a wide ellipse as
a beam, e.g. the "sector" antennas used for wide-area access point coverage emit a beam that has 90
degrees beamwith horizontally, but a very small beam angle in vertical direction.
Those antennas still operate within the physical limitations: it is not possible to make an antenna with a
circular beam of 90 degrees and still have a 15dB gain, but it is possible to do this with an elliptical beam
that has an area that corresponds to the 15 dB gain figure.
Also, the sidelobes of an antenna need to be taken into account: some energy is wasted in sidelobes
and this affects the calculation from gain to width of the main lobe.

W.r.t. physcal dimensions: an antenna has a "capture area" that can be calculated from the gain figure
with the inverse formula of the dish gain shown above. For a dish it is easy to visualize what this means:
it is the area of the signal that the antenna "grabs" and converts to electrical signal. In the case of a dish,
it is the area of the dish. But for other antennas, the same capture area figure applies.
This leads to the phenomenon that to achieve a certain antenna gain, a certain physical size of the antenna
is required (inversely proportional to the wavelength). And because beamwidth is just a function of gain,
to achieve a certain small beamwidth you need a certain physical size.

Those observations lead to the general principle that it is not possible to make a very small antenna that has
a very high gain and thus a good directivity. Anything you find on the market that claims such things
will be a fraud. So you will not find a 5GHz SXT with narrow beamwidth, not now and also not in the future
(remember this is not a technological limitation, it is a physical limitation). Only at higher frequencies
(shorter wavelength) it is possible to achieve a narrower beam in the same physical size.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 12:34 pm

@pe1chl; Very good explanation! :D

Still some questions though;

What happens if you for instance would make a metal tube the size of an SXT that is lets say 20, or 40 cm long (or unlimited length?)
Lets say you wan't to cross a street of 40 meters with on both end a SXT. Put a metal tube of the dia of an SXT of 40 meters and on both end the SXT's. What happens now?

In my simple mind all energy radiated will ultimately hit the other end? (Except for that part that actually is radiated to and towards the back.)
It will probably give a very distorted multipath receipt at the other end. (But 802.11n and ac like that?)
At the same time we will have almost 100% shielding against unwanted interference of foreign signals? Would this work?
And would there be a relation between this example of 100% tube coverage on the link compared to 0% tube on a standard SXT. Is there any formula for something like this?

I understand well narrow beam mean big size means high gain. But with the help of a deflector/shield (=tube?) could we not create a low gain narrow beam antenna? Like they sort of do with a tube enclosed yagi?

I also understand the higher frequency will be a solution maker here. The new 60Ghz technology will be usable but still on the expensive end.
We are in the process of ordering some 60Ghz backhauls though to cross 350 up to 450 meters. These I hope will get me out of interference issues and free some of my spectrum so my 5Ghz AP's in the same band will be performing better too...
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
n21roadie
Forum Guru
Forum Guru
Posts: 1889
Joined: Fri Aug 07, 2009 10:36 pm
Location: Limerick,Ireland

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 1:37 pm

Why would you want larger? Smaller is one of the advantages for 60Ghz.....
http://www.ignitenet.com/products/metrolinq/
I need to cover 1.8Kms and the max for 35cm dish is 1.5kms!
N21roadie,
Network 100% MT for Now?
 
ndor
newbie
Posts: 34
Joined: Sun Mar 28, 2010 8:28 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 2:54 pm

Using a metal tube, you will create a waveguide .At that diameter and a frequency between 5-6 Ghz you will not get anything at the other end .
Or ,if you have a signal, it will be very bad .
See waveguide transmission line theory
On the other hand, if use a metal tube with finite lenght , you will not create a narrow angle , on the contrary .
There are other more effective ways to eliminate interference.
One of them would be using bandpass filters between equipment and antenna.
Or a type of notch filters to remove certain frequencies that interfere with the equipment .
Of course this can not be done using integrated equipment.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 5:36 pm

Why would you want larger? Smaller is one of the advantages for 60Ghz.....
http://www.ignitenet.com/products/metrolinq/
I need to cover 1.8Kms and the max for 35cm dish is 1.5kms!
Ah, ok. I was reflecting too much to myself only... sorry. :?

But the attenuation of the signal of 60Ghz in free air is such that it is hardly impossible to bridge bigger distances. O2 (Oxygen) molecules are consuming the energy and water vapour or worse, rain, is a definite killer at some distances.
The only way to make links work over bigger distances is to pump a lot more energy in the air. You need a power plant and huge radio's to get it going and make sure no bird crosses.... you'll have instant KFC supply falling out of the sky! :D

Also, since the radio energy beam is so highly directional it makes aligning very difficult and even the slightest vibration would put the both end off-line.
I also presume as such distances temperature and humidity layers in the air start becoming affecting the link...

No, for above 1,5km you have to find other solutions I am afraid. (I also have some 1,5 to 2, 3 km links that could do with a cheap, but not 5Ghz, bridging..... Lease lines are just too expensive for the turnover we make on such links.... but interference is a pain nowadays...)
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
pe1chl
Forum Guru
Forum Guru
Posts: 5920
Joined: Mon Jun 08, 2015 12:09 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 8:47 pm

Of course it is easy to make an antenna that has low gain and narrow beam width: just take a high-gain antenna
and fit it with a wide band attenuator. You can easily obtain attenuators of e.g. 10dB or 20dB with N or SMA connectors,
and connect these inbetween your antenna and radio unit. (make sure you get a SHF-capable attenuator)

This will eliminate the overloading problem you get when using high gain antenna over a short path, but it will still
be a physically large antenna.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Mon Apr 11, 2016 8:55 pm

Of course it is easy to make an antenna that has low gain and narrow beam width: just take a high-gain antenna
and fit it with a wide band attenuator. You can easily obtain attenuators of e.g. 10dB or 20dB with N or SMA connectors,
and connect these inbetween your antenna and radio unit. (make sure you get a SHF-capable attenuator)

This will eliminate the overloading problem you get when using high gain antenna over a short path, but it will still
be a physically large antenna.
Yeah, and how to do that with an SXT? QRT? Sextant? DynaDish?

No, we know now, for small distance high focus beam with almost no side lobs and small antenna we have to go 60Ghz. Maybe Mikrotik jumps that train soon.....
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
sushilbiddu
just joined
Posts: 5
Joined: Wed Feb 24, 2016 5:13 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Thu Apr 14, 2016 6:41 am

You just can not compare a 2 degree parabolic antenna with a 10 degree flat panel, even if the gains are similar.
But you normally will not find those, because gain is the inverse of beamwidth.
When the sidelobes are reasonably down relative to the main lobe, and when the manufacturer is honest (this is
often not true in the antenna business!), you can directly translate the beamwidth to the gain and vice-versa.

The only variable is the characteristics of the sidelobes. These are different for focussing antennas like the dish
and phased-array antennas like the flat panel. And for a dish they can be changed by adding the shroud that limits
the overspill from the feed over the edges of the dish.
So, what is it they do with these yagi antennas?
2.4 GHz 15 dBi Yagi Antenna_T24150Y13602l.jpg
They are 2,4Ghz but the energy patterns aren't that much different?

At times you need to bridge only some 10, 50 or 100 meters with 5Ghz where a big antenna would way to powerful but a low gain antenna picks a lot of noise. (and probably still is too powerful)

Actually I need a 1 or 2dBm radio coupled to a 5º or 10º beam antenna that is not bigger than lets say an SXT. It looks like in 5Ghz it is just not possible.
Go with yagi antenna dual chain. They are highly directive and take very less interference compared to dish and panel. Their signals travels in narrow beam.
 
ste
Forum Guru
Forum Guru
Posts: 1813
Joined: Sun Feb 13, 2005 11:21 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sat Jul 02, 2016 2:54 pm

@pe1chl; Very good explanation!  :D

Still some questions though;

What happens if you for instance would make a metal tube the size of an SXT that is lets say 20, or 40 cm long (or unlimited length?)
Lets say you wan't to cross a street of 40 meters with on both end a SXT. Put a metal tube of the dia of an SXT of 40 meters and on both end the SXT's. What happens now?

In my simple mind all energy radiated will ultimately hit the other end? (Except for that part that actually is radiated to and towards the back.)
It will probably give a very distorted multipath receipt at the other end. (But 802.11n and ac like that?)
At the same time we will have almost 100% shielding against unwanted interference of foreign signals? Would this work?
And would there be a relation between this example of 100% tube coverage on the link compared to 0% tube on a standard SXT. Is there any formula for something like this?

I understand well narrow beam mean big size means high gain. But with the help of a deflector/shield (=tube?) could we not create a low gain narrow beam antenna? Like they sort of do with a tube enclosed yagi?

I also understand the higher frequency will be a solution maker here. The new 60Ghz technology will be usable but still on the expensive end.
We are in the process of ordering some 60Ghz backhauls though to cross 350 up to 450 meters. These I hope will get me out of interference issues and free some of my spectrum so my 5Ghz AP's in the same band will be performing better too...
How do the Metrolinqs work for you? I know this is a MT Forum. But MT does not do 60GHz so should be no problem ;-). We've some very short hops we want to use them and keep 5GHz free.
 
WirelessRudy
Forum Guru
Forum Guru
Topic Author
Posts: 3089
Joined: Tue Aug 08, 2006 5:54 pm
Location: Spain

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sat Jul 02, 2016 7:55 pm

The Metrolinq's are very good but still with some defects.
We have two complete links running; 1 x 348 and 1 x 655 meters.
It's a new product and manufacturer is still working on the firmware, Landatel actually warns for that.  :)
We have some issues with signal strengths were we should get more for the distance than the antennas actually show.
The 5Ghz build in backup is very unstable. And since we also don't know what the device needs to fail over (well, if the 60Ghz fails its clear, 5Ghz should take over. But what in heavy rain the 60Ghz starts to fade to a very poor level? And how will it come back?) and the 5Ghz is 802.11ac without tdma we don't use it but have our 'old' 5Ghz links as backup in ospf/bgp setup. 

The original delivered brackets are not the best design. They are thin and although not bending they allow the antenna to vibrate slightly in the wind and since the 60Ghz has such narrow beam (some  cm's over hundreds of meters) it makes the signal become variable.
We are testing their new bracket (from manufacturer) and although much better still not 100% and not available yet in Europe as far as I have seen. We've got a set for trials.
(And its said to be an "extra" so expect to pay for each unit.)

When the links run we have a very stable, low latency, high capacity link. On the 655 meters I already managed to 'pump' almost a gigabit of aggregated (700 one way, 300 the other way) tcp data over it. (3 Netmetal sending/receiving at the same time to one CCR on the other end one one even further up the line.) One tcp stream only does 250Mbps!
During this test ping with big package was around 2-6ms with hardly any jumps higher up.
When pumping some 500Mb aggregated we had a very stable ping of 0-2ms with hardly ever one going over 3ms. (Took minutes to see one..)
On our daily traffic (some 40-80Mbps) we have an almost always 0-1ms latency....
And this link is not having the best bracket, so it vibrates a bit in the wind. It lacks some 20dB in signal according manufacturer and we see it fluctuate some 6dB's...

 But THE big issue is that each of the two links we'd use now are stalling every 1, 2 or 3 days. Biggest up-time is now 3 days and it needs a power cycle to bring it back. Not nice!

But since our original 5Ghz links in the heavy congested spectral performed soooo bad with poor speeds and latency in the order of 2-8ms with regular jumps into 40's and 60's we keep the metrolinq's running and hope most clients will notice the improved quality were only some will notice the cuts. After installing the metrolinq's on our main backbone (it had 2 Netmetals with 80Mhz wide channel. Capacity plenty but CCQ never better than 80% and latency of 4-8ms average and 40-60 max. Single tcp stream only 30-40Mbps.....) we say an increase of client traffic of some 10% overall...

In the meantime I am on a daily basis communicating with the manufacturer to get their firmware's sorted asap and the brackets improved. They are very helpful though so I have good hope they nail the important issues soon and then we have some excellent product! 

One of the nice things is that we have now two links shooting from one tower with only some 20º angle in direction and 2,5meter vertical separation on the tower (=mast) and even in the same frequency they don't 'see' each other! Try that with the best shielded and highest gain 5Ghz antennas. Even RF elements new simper line cones 'see' each-other. 

MetroLinq announced a PtMP AP sector antenna as well which could be a nice alternative to the 5Ghz WISP industrie if they manage to get the problems solved and the price down...
(From a fiber connected AP bridge a couple of buildings with Gigabit speed over wireless! :-) )

So yeah they work well but not reliable and works still needs to be done. But I did see in Landatel's shop 40 or so available units were sold out in only 3 days...... They just have a new lot in... you'd better hurry up to get them. I had to wait 5 weeks for the second link....
Show your appreciation of this post by giving me Karma! Thanks.

Rudy R. Puister

WISP operator based on MT routerboard & ROS.
 
ste
Forum Guru
Forum Guru
Posts: 1813
Joined: Sun Feb 13, 2005 11:21 pm

Re: Microstrip (flat panel) versus eliptical (disk) antenas?

Sat Jul 02, 2016 8:47 pm

The Metrolinq's are very good but still with some defects.
We have two complete links running; 1 x 348 and 1 x 655 meters.
It's a new product and manufacturer is still working on the firmware, Landatel actually warns for that.  :)
We have some issues with signal strengths were we should get more for the distance than the antennas actually show.
The 5Ghz build in backup is very unstable. And since we also don't know what the device needs to fail over (well, if the 60Ghz fails its clear, 5Ghz should take over. But what in heavy rain the 60Ghz starts to fade to a very poor level? And how will it come back?) and the 5Ghz is 802.11ac without tdma we don't use it but have our 'old' 5Ghz links as backup in ospf/bgp setup. 

The original delivered brackets are not the best design. They are thin and although not bending they allow the antenna to vibrate slightly in the wind and since the 60Ghz has such narrow beam (some  cm's over hundreds of meters) it makes the signal become variable.
We are testing their new bracket (from manufacturer) and although much better still not 100% and not available yet in Europe as far as I have seen. We've got a set for trials.
(And its said to be an "extra" so expect to pay for each unit.)

When the links run we have a very stable, low latency, high capacity link. On the 655 meters I already managed to 'pump' almost a gigabit of aggregated (700 one way, 300 the other way) tcp data over it. (3 Netmetal sending/receiving at the same time to one CCR on the other end one one even further up the line.) One tcp stream only does 250Mbps!
During this test ping with big package was around 2-6ms with hardly any jumps higher up.
When pumping some 500Mb aggregated we had a very stable ping of 0-2ms with hardly ever one going over 3ms. (Took minutes to see one..)
On our daily traffic (some 40-80Mbps) we have an almost always 0-1ms latency....
And this link is not having the best bracket, so it vibrates a bit in the wind. It lacks some 20dB in signal according manufacturer and we see it fluctuate some 6dB's...

 But THE big issue is that each of the two links we'd use now are stalling every 1, 2 or 3 days. Biggest up-time is now 3 days and it needs a power cycle to bring it back. Not nice!

But since our original 5Ghz links in the heavy congested spectral performed soooo bad with poor speeds and latency in the order of 2-8ms with regular jumps into 40's and 60's we keep the metrolinq's running and hope most clients will notice the improved quality were only some will notice the cuts. After installing the metrolinq's on our main backbone (it had 2 Netmetals with 80Mhz wide channel. Capacity plenty but CCQ never better than 80% and latency of 4-8ms average and 40-60 max. Single tcp stream only 30-40Mbps.....) we say an increase of client traffic of some 10% overall...

In the meantime I am on a daily basis communicating with the manufacturer to get their firmware's sorted asap and the brackets improved. They are very helpful though so I have good hope they nail the important issues soon and then we have some excellent product! 

One of the nice things is that we have now two links shooting from one tower with only some 20º angle in direction and 2,5meter vertical separation on the tower (=mast) and even in the same frequency they don't 'see' each other! Try that with the best shielded and highest gain 5Ghz antennas. Even RF elements new simper line cones 'see' each-other. 

MetroLinq announced a PtMP AP sector antenna as well which could be a nice alternative to the 5Ghz WISP industrie if they manage to get the problems solved and the price down...
(From a fiber connected AP bridge a couple of buildings with Gigabit speed over wireless! :-) )

So yeah they work well but not reliable and works still needs to be done. But I did see in Landatel's shop 40 or so available units were sold out in only 3 days...... They just have a new lot in... you'd better hurry up to get them. I had to wait 5 weeks for the second link....
Thanks.
Hey @MT you could do this better ;-)). 

Who is online

Users browsing this forum: MSN [Bot] and 18 guests