[TowerTalk] Yagi gain vs rotary dipole.

[Joe Subich, W4TV]

> ## Ok, what are u saying here. Lets say a 20m dipole and a 3-el 20m
> yagi.... both at 70 feet.At really low angles..say 0-10 deg.....
> will the 3-el yagi have even more than 5.2 db of gain ?? Or put
> another way... even though 70 feet = aprx 15 deg take off angle of
> main lobe.... does the yagi exhibit more gain vs the dipole at angles
> below 15 deg ?

A little work with EZNEC provides some answers ...

Using the model of a five element 20 meter yagi at 50 feet and a dipole
at 50 feet above *real* average ground ...

The dipole has a peak gain of 8.0 dBi at 21 degrees.

The 5 element Yagi shows 14.4 dBi at 18 degrees

  Angle     Dipole       Yagi
   2        -7.7        -0.1    dBi
   4        -1.8         5.7    dBi
   6         1.5         8.9    dBi
   8         3.7        11.0    dBi
  10         5.2	       12.4    dBi
  12         6.3        13.4    dBi
  14         7.1        14.0    dBi
  16         7.6        14.3    dBi
  18         7.9        14.4    dBi
  20         8.0        14.3    dBi
  22         7.9        13.9    dBi
  24         7.6        13.4    dBi
  26         7.1        12.6    dBi
  28         6.4        11.6    dBi
  30         5.5        10.4    dBi

73,

   ... Joe, W4TV


On 2014-11-25 1:52 PM, Jim Thomson wrote:
> Date: Mon, 24 Nov 2014 20:46:14 +0100
> From: "Peter Voelpel" <dj7ww at t-online.de>
> To: "'Towertalk'" <towertalk at contesting.com>
> Subject: Re: [TowerTalk] Yagi gain vs rotary dipole.
>
> Hi Jim,
>
> To get the same signal strength -4db compared to the 3el yagi on low angles
> with your dipole that dipole must be mounted much, much higher then the yagi
> and even higher with more elements on the yagi.
>
> Tribanders at the same height as the 6 el monobander certainly will have
> identical gain when the effective boom length is identical and enough
> elements sitting on it.
>
> I don?t build yagis for getting more gain above dipoles at high lobes, but
> for low elevation angles and better receiving.
>
>
> 73
> Peter
>
> ##  Ok, what are u saying here.  Lets say a 20m dipole and a  3-el 20m yagi.... both at 70 feet.
> At really low angles..say 0-10 deg..... will the 3-el  yagi have even more than 5.2 db of gain ??
> Or put another way... even though 70 feet  = aprx 15 deg take off angle of main lobe.... does the
> yagi exhibit more gain vs the dipole at angles below 15 deg ?
>
> ##  anytime I have done yagi to dipole tests in the past..the difference was astounding.  I always
> assumed it was cause the dipole was fixed...not rotatable...  and not quite broadside to the station.
>
> Jim
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>