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Discussion Starter #1
Hi to all ,would like to know anybody have .stl file for DIY antenna parts if i like to print from Plastic.?Thank you
 

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Parts-1a for antenna analyzing

Classic 8-bay Antenna UHF and VHF-High Band
Antenna UHF good directivity

Band receives: UHF and VHF-High
frequency: 470MHz to 698MHz
US Channels 14-51
UE Channels 21-48 (470 to 690 MHz)
Gain: min a 470MHz: 15.1dBi / max a 698MHz: 17.3 dBi
Gain maxim of frequency: 698MHz
SWR: < 1.9 UHF 470 to 698 MHz
Relation Front to back ratio: < = 21 dB
Impedance: 300/75 ohms
Usage of Matching Transformer 300 to 75 Ohm Balun
Usage of 50MHz-900MHz splitter/combiner
Beam width: 26 - 18 degrees
The diameter of mast: 30 mm.
Dimensions:
Width = 112.8 cm.
Height = 92 cm.
Depth = 13.64 cm.

Program used:
MMANA-GAL basic is freeware an antenna-analyzing tool based on the moment method
http://hamsoft.ca/pages/mmana-gal.php







Full document of Antenna analyse:
MQ_3968_v1_A
 

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Parts-3p for antenna modelling parts printable

Modelling of parts the antenna in BLENDER 3D
Dimensions in millimeter
Designs 3d parts of antenna
printable in classic filament extrude 3d printer
nozzle example 0.4mm (0.5-0.3)
I haven't done the testing PLA is the usual material recommendation for printable parts of antenna

Usage of screw diameter 3mm
Usage of screw diameter 4mm





Full document of Antenna printable:
MQ_3968_v1_P
 

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Discussion Starter #5
Thank you for your time and replay this is the parts what i was looking for.Someone from Open Scad forum helped me to do something similar,but this looks perfect.Thank you again.
For this project i try to use PETG.
 

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I completed my DYI 8 bay antenna, construction efficient might be 65%, however I'm looking to squeeze more gain on weak signals.

Prototype 1



Using to an direct coax connection to two parallel 300 ohm twin lead and that feed the antenna. and the two 4-bay sections must be connected in phase. If they are not connected in phase, the main lobe will split in two with a null in the center of aim.

My own experiments are with (local) TV stations.
The "sweet spot" for the location of the antenna this in my bedroom to the side of a window, and coax length is approx 16ft from the antenna to the point of connection TV.

In my impromptu test of the start prototype (per Sony TV signal diagnostic display) the reception was noticeably better on weak and half stations on my TV signal that 4 bay bow-tie antenna.

The goal is just to get a better combined of two antenna.

Reference:
The next text is of web page.
<<<You can dispense with the quarterwave transformer if you're willing to accept 0.5 dB of mismatch loss from the resulting SWR of 2.>>>
 

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Prototype 2

Combine them in parallel from two parallel 300 ohm twin lead, giving you 150 ohms. Convert that to 75 ohms with a 1/4 wave matching section of 106.1 ohm. This also has the need to have the two 4-bay sections in phase.
Code:
Combine from two parallel 300 ohm twin lead
300   300
  \   /
   150
    |
    ?

    75

Zi=impedance input of line
Zl=impedance load of line
Zo=characteristic impedance of line require

Zo=√(Zi)(Zl)
Zo=√(75)(150)
Zo=106.07 ohm
 ?=106.07 ohm

Z load = 150 ohm
Z line = 106.07 ohm

Z=(106.07^2)÷150
Z=75.00
My reference:
The next text is of web page.
TV Antennas
Combining Stacked UHF-TV Arrays
<<<You can combine 300Ω antennas with two 300:75Ω baluns and one of the methods described above. For lower loss, use equal lengths of 300Ω line and join them to obtain 150Ω. Match this to 75Ω with a 108Ω quarter wave transformer comprised of the center conductors of side-by-side 311⁄16″ lengths of 54Ω Belden 8219 RG-58A/U. Connect but float the shields. Use a ferrite choke on the 75Ω feed line. SWR is 1.24 maximum and total loss 0.1 dB maximum over 470–698 MHz.>>>

Software: Transmission Impedance Calculator
web page:
Download:
http://www.vk5dj.com/VK3UM Transmission Line Calculator Ver 1.21 Install.zip

Coaxial Rigid Quarter Wave Line

Results.
Using a 1/4 wave transmission line section work better significantly lower loss than the prototype 1. It's only an issue for the weak/distant stations. This will give you UHF only.

Increase the signal in the channel mas loss but to an don't there are image in the tv.

Don't succeed the purchase in local shop the ferrite that suggests in the reference, to if that add another type of ferrite that are not felicitous.


The signal go up to 33% with what achieve the image with intervals of pixelation in different hours of the day.

My Sony TV signal diagnostic display the reception in an bar of 0% to 70%

solve problems as twin-lead cable is more susceptible to picking up interference y the ferrite.

Antenna image construction:
prototype_2
 

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flaw is that your quarter wavelength transmission line is a quarter wavelength at one frequency.
Just use conventional broadband 300->75 ohm baluns, equal length jumpers in to a conventional broadband combiner and be done with it. If there was a better way, the antenna MFRs would be doing it.
 

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majortom

Thanks for taking your time to read and comment on the post. If you are absolutely right, it would be the easiest and I practice what you say.
in post #2 the antenna I posted was like that.

Why prototype 1, 2, 3 and the end?

1) I wanted to experience the alternatives that are described in the references in each prototype, do not build how described but get closer.

2) I couldn't buy a combine at the local store.

As my weak stations were located in the center of the 470-698 MHz band, testing a transmission line with a quarter wavelength at the frequency of 584 MHz would increase reception and it was so in the prototype end.

It was interesting to observe the signal levels of each prototype. I was very surprised that the prototype end returned VHF-high.

If you do not have a combine the harness of the prototype end would be an alternative to test.
 

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Prototype 3

My weak channels are near the center of the old band UHF (470-698 MHz), don't care about channels at the far end of the band.

Solved the problem with a harness design of two 1/4 wave segments of 212.2 ohms, that is for combine them in parallel giving you 106.1 ohms. That convert to 75 ohms.

My references:
Temporary page

Solve the problem of the ferrite making a 1:1 balun for UHF TV to 75 ohms (BAL and UNBAL).
My references:
Balun Guanella Current1:1


Thus is how I made it. I used a binocular core that are easily obtained from TV baluns (matching transformers 75/300 ohms generic) for the core. I used four piece 2.5" of 30 gauge wire(0.25mm) bifilar or two parallel windings 3.5 turns in each side this give a total of 7 turns.


The second balun 1:1 I used a recycled toroidal that was of 12.5mm in diameter for the core of color red. and two piece (5.25") of 0.4mm gauge wire bifilar windings of 6 turns.

Tested by adding or subtracting turns on the of transformer (balun) 10 turns, tuning more for VHF (54-216 Mhz) than UHF (470-698 Mhz)

results.
My two baluns work well on the entire UHF band for local signals and for more distant channels. They also perform well in the VHF band for local channels.

The signal goes up to 38% with what achieves the image more stable and does not exist pixelation.

Antenna image construction Baluns:
prototype_3
 

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Prototype End

DYI 8 bay antenna old band UHF (470-698 MHz).


I completed my DYI 8 bay antenna, construction efficient might be 75%. and my tested weak channels are near the center of the old band UHF (470-698 MHz).
My Sony TV signal diagnostic display the reception in an bar of 0% to 70% of signal.

0%||||||||||||||||35%||||||||||||||||70%

The signal goes up to 42% in channel of test.
Work well on the entire UHF band and perform well in the VHF high-band.






Prototype End.

Parts Antenna Printable and modelling in (LibreCAD, MMANA-GAL basic, Blender):
Antenna_v3_0
Image antenna construction:
Antenna_v3_1
Image antenna harness construction:
Antenna_v3_Harness_end
 

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4 bay for new band UHF (470-608 MHz)
Antenna (Classic-Bowties)

Parts Antenna Printable, modelling, drawing and MMANA-GAL file in (LibreCAD, MMANA-GAL basic, Blender):
4Bay_470-608_MHz
 

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8bay for new band UHF (470-608 MHz)
Parts Plastic for support of aluminum square tube (3/4 x 3/4 x 1/16 wall)
Antenna Dimensions in Inches
Parts Plastic Dimensions in millimeter
Is not necessary printed all the parts each one has his form to build.

Add analyze in 4nec2 antenna 4Bay (auto segmentation off) and an example of 8bay with harness all the archives this here:
AntennaMQ_4Bay_8Bay
FINISH
 

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Discussion Starter #16
8bay for new band UHF (470-608 MHz)
Parts Plastic for support of aluminum square tube (3/4 x 3/4 x 1/16 wall)
Antenna Dimensions in Inches
Parts Plastic Dimensions in millimeter
Is not necessary printed all the parts each one has his form to build.

Add analyze in 4nec2 antenna 4Bay (auto segmentation off) and an example of 8bay with harness all the archives this here:
AntennaMQ_4Bay_8Bay
FINISH
Hi jop would like to know do you have the .stl file for the plastic parts?? Thank you
 

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janos
They are in post # 15 named AntennaMQ_4Bay_8Bay.zip inside a named folder (STL_print_3d_v6), which can be used for 4bay or 8bay anyway here are only the file .stl
STL_print_3d_v6
 
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