No name antenna 27+ dbi

[Sl4va 11]

I watched the video on YouTube, test different antennas. The guys showed a new parabolic antenna feed. A very interesting design! And easily repeatable at home.

I understand it is based on Log-periodic antennas?

[clanon 246]

Link...?

 

27DBi... ...only on 5.8ghz...hard to get that on 2.4...need more than 1 m2 area...

Edited August 9, 2020 by clanon

[Sl4va 11]

16 minutes ago, clanon said:

Link...?

 

27DBi... ...only on 5.8ghz...hard to get that on 2.4...need more than 1 m2 area...

it is broadband. from 800 to 2600 ghz

 

[clanon 246]

I like it...

the fine mesh wire makes it work as a sheet metal reflector...but WIND LOADs are bigger...

we need to get the dimensions for the LogPeriodic feed...

 

Edited August 9, 2020 by clanon

[Admin 2545]

,,, this is not a nameless antenna ,,, it is called Kroks KNA+ 27 800-2700 MHz(adjusted)

,,, attention to the title ... !!!

[Sl4va 11]

16 minutes ago, Admin said:

,,, this is not a nameless antenna ,,, it is called Kroks KNA 27 1700-2700 MHz

 

no! irradiator Kroks KNA 27 looks different (look in google)

I watched this video, it says that this irradiator is not even available yet!

 

[Admin 2545]

,,, and then what are the dimensions of the parabolic reflector ... ??

[Sl4va 11]

13 minutes ago, Admin said:

,,, and then what are the dimensions of the parabolic reflector ... ??

parabolic reflector from Kroks KNA 27

P.S. As it goes on sale, you need to buy, take measurements, and make a drawing

Edited August 9, 2020 by Sl4va

[Admin 2545]

,,, no, one of this ...

630x600x100mm

810x780x100mm

910x880x160mm

...it must to be...!!!

[Sl4va 11]

I meant the antenna feed itself

[jnkwqlqn 0]

LPDA feed, laser cut.

[Admin 2545]

3 minutes ago, jnkwqlqn said:

LPDA feed, laser cut.

Of course....!!

[jnkwqlqn 0]

But you have to watch the impedance! Is there anyway to calculate impedance for LPDA boom distance in CST, etc?

[clanon 246]

Yes...need LOGPERIODIC and reflector data...

[Mishka 10]

To continue on the LPDAs, there are a number of interesting PCB antennas by Kent Britain WASVJB: https://www.wa5vjb.com/products1.html

I tried to simulate that one at 850-6500 MHz band range with CocoaNEC (no Windows here, sorry) using the method described at https://hamwaves.com/lpda/en/index.html, and eventually reached similar parameters, but my antenna is definitely larger. For 850 MHz the λ/2=17.64 cm, so I'm surprised how WASVJB was able to fit it into the 13.4 cm PCB.

For the simulation I've set tau = 0.85, sigma = 0.12. Element to element transmission line impedance is 75 Ohm. All elements are of constant width 0.16 mm.

Exact location of the elements is as follows (all dimensions in meters):

Spoiler

 WIRE      OFFSET     LENGTH
    1      0.0000     0.0882  <- quarter wave of 850 MHz, must have two of those
    2      0.0423     0.0749
    3      0.0783     0.0637
    4      0.1089     0.0541
    5      0.1349     0.0460
    6      0.1570     0.0391
    7      0.1757     0.0333
    8      0.1917     0.0283
    9      0.2053     0.0240
   10      0.2168     0.0204
   11      0.2266     0.0174
   12      0.2349     0.0148
   13      0.2420     0.0125
   14      0.2480     0.0107
   15      0.2532     0.0091

 

Simulation data:

Spoiler

 

[clanon 246]

What dielectric...? 

thickness , dielectric constant...

(there's ALWAYS losses , you know)

[Mishka 10]

18 hours ago, clanon said:

What dielectric...? 

thickness , dielectric constant...

(there's ALWAYS losses , you know)

The antenna is in free space.

All elements are of constant diameter 0.16 mm or slightly above 6 mils.

 

[clanon 246]

LPDA.pdf

[Admin 2545]

,,,it must to see and this...

 

[clanon 246]

Yurik says...: (about this LPDA)

1) isolation between ports. if, for example, the decoupling is zero, then VSWR = 1 for the measured port (all 100% of the energy has consistently crossed over to the second port). To achieve an isolation of at least 20 dB, extremely stringent requirements for line symmetry are required. One line (pair of plates) does not interfere with the second pair only in case of precision symmetry. Due to the installation of elements as a continuation of the plane of the plate from which the line is made, symmetry is impossible. For symmetry, the elements of the dipole must enter perpendicular to the plane of the collecting strip.

2) the design of the balun. LPDA, like most antennas, has a balanced (differential) output. A 1: 1 balun is required to match an unbalanced line (coaxial cable). Most often it is done by laying the cable inside a hollow line to the point of zero potential. in MIMO, the cable can no longer be laid like this (in laboratory antennas this is done using a hollow profile of a complex cross-section) from this video it is not clear how it is laid 3) The LPDA antenna must have a short-circuited line behind it (continuation) of a certain calculated length. in the video, this structural element was simply excluded by an effort of will

4) to create antennas with a direct output to 50 Ohm, collecting lines with a very low impedance have to be used. The distance between the stripes should be many times less than the width of the stripes. But for MIMO, a constructive restriction is imposed that the distance between the lines is greater than their width (at least by the value of the constructive gap). Two strips with a distance between them equal to their width have Zo = 160 Ohm, which does not allow designing an LPDA with an output of 75 or 50 Ohms.In addition, any LPDA has an unstable phase center (too mobile even for one single band, only within one 3G range, the difference between uplink and downlink reaches 2.5 centimeters

[Mishka 10]

To design something more or less practical, I've put a model for dual-band LPDA for 2.4GHz and 5GHz WiFi into the cocoaNEC. The antenna was designed to be buildable from a copper wire S = 2.5 sq.mm, d = 1.7 mm. All other dimensions including distance between feeding rods (the boom) were optimized for VSWR using stochastic gradient descent. The antenna is matched to 50 Ohms symmetrical input.

Both the NEC cards deck and the cocoaNEC SGD code are available. Please note though, to build this particular antenna I've added 2.6-4.9 GHz band-stop "virtual filter" to prevent SGD from optimizing for the non-interested bands. As a bottom line, it was calculated for 2.2-2.6GHz and 4.9-6 GHz. Considering the WiFi bands only, max VSWR is below 1.4 at 5875 MHz and 2485 MHz.

Simulation data:

Spoiler

Azimuth (horizontal + vertical polarization):

Elevation (horizontal + vertical polarization):

[Admin 2545]

Mishka,try to design a log-periodic  antenna as above (Kroks KNA+ 800-2700 MHz)

[Mishka 10]

On 11/16/2020 at 9:46 AM, Admin said:

Mishka,try to design a log-periodic  antenna as above (Kroks KNA+ 800-2700 MHz)

I believe the antenna is made of a single plate, and then bent near the center. Perhaps, the feed points located at a horizontal and a vertical boom sides.

Well, I must admit it's not an easy task to model it in the cocoaNEC. The NEC has support for patches, but the surface of every element must be described in 3D with hundreds, if not thousands of those. I could describe the model with a wired mesh. The mesh will have at least two times elements less and is simper to program. For this particular antenna with five dipoles per side, there are about 20 parameters to optimize - five dipole length & width, plus element to element boom length & width. And there's also the reflector.

Does CST, or HFSS, or FEKO, or anything else besides the cocoaNEC support a programming language, or maybe have a built-in gradient descent or something like that to do the job?

[Admin 2545]

,,, okay, it's enough to just give the dimensions...!!!

[clanon 246]

try to work with this...

is the closest i got...didn't like it...TWO peaks of resonance very close

LPDA lte.cst