Hey fellas I have a question

[Mr Clean]

I know most programs for beams are setup for flat side. My question is can a vert beam have as good side rejection as a flat side beam. I know front to back can be very good on a vertical but have been told side rejection is lacking.

 

[C2]

sounds right to me.

 

[W5LZ]

The shape of the radiation pattern has very little to do with the polarization of an antenna. (fwrd gain, FB,side rejection)
- 'Doc

 

[Captain Kilowatt]

All specs I have seen for the same antenna mounted either V or H show that the F/S ratio is only slightly worse for a verticle config.The beamwidth is slightly narrower for a H config.These values were not something you would really see in the real world but were measurable only using lab grade field strength gear.For all practical purposes there is no differance.

 

[C2]

The shape of the radiation pattern has very little to do with the polarization of an antenna. (fwrd gain, FB,side rejection)
- 'Doc

That might be true, but could the shape of the radiation pattern be affected by the polarization of the antenna?

What I mean is that a horizontally polarized (oriented?) dipole would have a figure 8 radiation pattern and a vertically polarized (oriented?) dipole would have a circular (omni?) radiation pattern.

 

[Captain Kilowatt]

The shape of the radiation pattern has very little to do with the polarization of an antenna. (fwrd gain, FB,side rejection)
- 'Doc

That might be true, but could the shape of the radiation pattern be affected by the polarization of the antenna?

What I mean is that a horizontally polarized (oriented?) dipole would have a figure 8 radiation pattern and a vertically polarized (oriented?) dipole would have a circular (omni?) radiation pattern.

While that may be true for a single element the original question was asked about beam antennas.AFAIK the single element is the only case where that may be true.

 

[C2]

TY

 

[Toll_Free]

The shape of the radiation pattern has very little to do with the polarization of an antenna. (fwrd gain, FB,side rejection)
- 'Doc

That might be true, but could the shape of the radiation pattern be affected by the polarization of the antenna?

What I mean is that a horizontally polarized (oriented?) dipole would have a figure 8 radiation pattern and a vertically polarized (oriented?) dipole would have a circular (omni?) radiation pattern.

In free space, no.

In the real world, things like your mast / tower, guy wires and the like come in to play.

--Toll_Free

 

[C2]

What happened to freecell's post?

And what do you mean "no?"

I'm assuming you mean that the pattern is roughly a teardrop shape, fully symetrical in both dimentions, in free space?

of course the feedline, mast, and relative position of ants on the ground have an impact on your radiation pattern. That is nothing more than a statement of facts.

 

[W5LZ]

C2,
In free space a dipole's radiation pattern is roughly the shape of two round baloons touching at one point. No 'tear drop' pattern. In real world patterns, the shape depends on the antennas environment, primarily it's height above ground. If you can imagine taking those two touching baloons and pressing them against a flat surface, that pushing force being applied only at the contact point which is the antenna, you get the rough equivalent radiation pattern, sort of (and boy, is that a ~rough~ example!). Just for the 'heck' of it, see if you can find one of the free examples of "EZNEC" and play around with height. Really some big changes possible with just a few feet difference (few dozen feet in most cases, depending on frequency). Don't take it as 'gospel' though, unless you wanna spend months entering environmetal data to make the thing really show you what's happening (not me, too @#$ lazy!).
- 'Doc