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aq_mishu
Joined: 16 Jul 2007
Posts: 120
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 05 May 2009 20:48 9 elements yagi 435 mhz |
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Guys,
This is the antenna...
| Code: |
│ ┌─────────────────────────────┤
│ OPERATING FREQUENCY........... {MHz} 435 │ │
│ REFLECTOR LENGTH.............. { m } .345 │ FORWARD GAIN = 11.29 dBi │
│ FED ELEMENT LENGTH............ { m } .33 │ │
│ REFLECTOR SPACING............. { m } .086000 │ F to B RATIO = 72.24 dB │
│ #of DIRECTORS 7 Rfl EL DIAM {mm } 5 │ │
│ D 1 SP { m } .069000 D 1 LEN { m } .315 │ INPUT IMPEDANCE = │
│ D 2 SP { m } .081000 D 2 LEN { m } .296 │ 83.8 +j 26.6 Ohms │
│ D 3 SP { m } .095000 D 3 LEN { m } .289 │ │
│ D 4 SP { m } .112 D 4 LEN { m } .282 │ ARRAY LENGTH = 0.91 m │
│ D 5 SP { m } .131 D 5 LEN { m } .259 │ │
│ D 6 SP { m } .155 D 6 LEN { m } .254 └─ F4: Optimize ───── F6: BW ─┤
│ D 7 SP { m } .181 D 7 LEN { m } .236 ┌─ F3: Plot ───── F5: Mode M ─┤
Bend dia 40mm; Folded dipole.
================================================================================
│ ┌─────────────────────────────┤
│ OPERATING FREQUENCY........... {MHz} 435 │ │
│ REFLECTOR LENGTH.............. { m } .351 │ FORWARD GAIN = 13.20 dBi │
│ FED ELEMENT LENGTH............ { m } .326 │ │
│ REFLECTOR SPACING............. { m } .087000 │ F to B RATIO = 58.45 dB │
│ #of DIRECTORS 9 Rfl EL DIAM {mm } 10 │ │
│ D 1 SP { m } .069000 D 1 LEN { m } .314 │ INPUT IMPEDANCE = │
│ D 2 SP { m } .079000 D 2 LEN { m } .304 │ 57.7 +j 23.1 Ohms │
│ D 3 SP { m } .089000 D 3 LEN { m } .297 │ │
│ D 4 SP { m } .102 D 4 LEN { m } .294 │ ARRAY LENGTH = 1.20 m │
│ D 5 SP { m } .116 D 5 LEN { m } .285 │ │
│ D 6 SP { m } .133 D 6 LEN { m } .285 └─ F4: Optimize ───── F6: BW ─┤
│ D 7 SP { m } .151 D 7 LEN { m } .278 ┌─ F3: Plot ───── F5: Mode M ─┤
│ D 8 SP { m } .173 D 8 LEN { m } .289 │ Tab: Steps El's │
│ D 9 SP { m } .197 D 9 LEN { m } .263 │ │
Bend dia 50mm; folded dipole.
=================================================================================
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Both of them are using copper rods (first one is with 5mm and second one is with 10mm). Folded dipole. Now i need to make it okey for 50ohm lines... so what should i do?? just the 4:1 BALUN?? or some thing else??? guys please help me since i'm badly struck and i'm damn new in this field...
Mishu~
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vfone
Joined: 10 Oct 2001
Posts: 2327
Helped: 327
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06 May 2009 8:04 yagi antenna impedance |
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| 4:1 balun it will match 50 ohms to 200 ohms. The usual impedance of a folded dipole is somewhere between 200 and 300 ohms. In your simulation you get much smaller than this.
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FvM
Joined: 22 Jan 2008
Posts: 5159
Helped: 767
Location: Bochum, Germany
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06 May 2009 8:15 length 304 mhz antenna |
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Connecting the second antenna with a 1:1 balun, or just a ferrite core around the coax cable isn't bad as a first step.
You may want to adjust either the dipole dimensions or use a tuning network to improve the matching, but doesn't make sense without an actual impedance measurement.
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06 May 2009 8:15 Ads |
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aq_mishu
Joined: 16 Jul 2007
Posts: 120
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06 May 2009 19:10 how do i make folded dipole yagi |
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| well... according to the simulation, i'll make it... then since folded dipole, then i can not actually change the length. so how can i first measure the impedance and then based on that reading, how to make it ok for 50ohm??
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bkd
Joined: 18 Dec 2005
Posts: 109
Helped: 1
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18 Jun 2009 9:35 qy4 yagi |
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| Can you aq_mishu supply me this yagi calculation program
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aq_mishu
Joined: 16 Jul 2007
Posts: 120
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28 Jun 2009 17:41 yagi with folded dipole match |
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| please send me your email address and i'll send it through email... infact you can do a search using "QY4 Yagi". It is a DOS based program.
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