Scanner antenna - yagi vs tram

[BITT211]

Which is stronger reception scanner antenna ,

tram uhf 406-512 mhz [6.5 gain] omnidirectional type
or
yagi uhf 450-470 mhz [7.1 gain] 3 elements

have the tram mounted on 50' tower , my location is higher elevation

tram is working fine , hooked into a striedsburg powered coupler , heliax coax- 7/8"

looking for a little more distance , i am located on the rear part of my county so very little reception would be coming from rear of yagi . The yagi cover pattern would be fine for my coverage i need.

Would it be worth while in replacing tram with yagi ? Tower has tilt base , no problem there..

Thanks for any input

 

[popnokick]

Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 7_0_6 like Mac OS X) AppleWebKit/537.51.1 (KHTML, like Gecko) Version/7.0 Mobile/11B651 Safari/9537.53)

If you don't need to have much reception off the back of the beam (Yagi), then it will definitely outperform an omnidirectional antenna in the desired frontal lobe / coverage area. When properly installed of course.

 

[WA0CBW]

Are both antennas using the same db's (dbd or dbi) ? If they are the same the difference is .6 db. It would be difficult to measure much less hear by ear a .6 db difference. The difference you might notice would be in that the beam would have a narrower beam width. You might have to turn the beam to hear different stations if they were beyond the beam width.
BB

 

[jackj]

The difference in gain is negligible however there is a big difference in the antenna patterns. An antenna's gain is measured at the point in it's pattern where it has the MOST gain. A yagi's gain drops off to either side of that point. The beam width is measured at the points where the gain has dropped off by 3db from the peak and a drop of 3db is half of the power. On the other hand, an omnidirectional antenna has the same gain in all horizontal directions.

So an omni will out perform a yagi in most directions. The lone exception will be when the yagi is pointed directly at or very close to the station. There are very good reasons to use a yagi but they all have to do with taking advantage of a yagi's directional pattern, not its gain.