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having trouble for 435 Mhz Yagi antenna Input impedance

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aq_mishu

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9 elements yagi 435 mhz

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.

=================================================================================
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~:?::?:
 

yagi antenna impedance

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.
 

length 304 mhz antenna

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.
 

how do i make folded dipole yagi

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??
 

qy4 yagi

Can you aq_mishu supply me this yagi calculation program
 

yagi with folded dipole match

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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