Angle of Radiation Loss

[ROC1]

I know there is a significant db loss when polarization between two antennas is different. When polarization is the same (in this case vertical) but the angle of radiation is different, is there any loss, more specifically in a DX situation? (1/4 wave vs 1/2 wave).

Thanks...

 

[dxhound]

There will never be two IDENTICAL antennas with IDENTICAL "angles of attack"

Now if you have a vertical with a very low angle of attack (lets say 90deg for this discusion) and you are talking to a local station within 60 miles and they have a higher angle of attack (say 30 deg) but there are running the same power output and there antenna is " Identical"to yours in respect to gain. They will here you better than you will here them.

The reason being is that there signal has most of the RF density broadcasting upward toward the sky, versus yours where the majority of the RF density is being transmitted along the earths surface.

This same principal however does not work for DX. Once RF enters the atmosphere, the D and E regions as well as the others will "refract" the signal at verying degrees. So if the majority of your signal hits the atmosphere at lets say a 45 degree angel, it may exit at a 70 degree angle. Theres also other phenomenon to consider, like coastal ducting, Aura, Sparadic E, meteor reflection, and so on.

As a general rule of thumb The lower the angel of radiation, The further DX you will work.
And the Higher the angel of radiation, the closer dx you will work.

This also becomes null when considering what frequency you are refrencing. The higher the frequency the less effect the atmosphere will have.

I hope this isnt too confusing

 

[W5LZ]

I'm afraid there's no definite answer. 'dxhound' has it about as 'right' as you can predict, which means there's a very definite 'maybe' it'll make a significant difference. It just isn't an "it's always this way" answer, just like the vertical/horizontal thingy after one 'skip' or bounce off the ionosphere.
The 'catch' is in the word 'significant'. It's a fairly safe bet that there will be some difference. That difference may or may not be all that significant.
- 'Doc

Don't you just love answers like that? More fun than a toothache, but not by much.

 

[C2]

WRT vertical/horizontal, you might not have caught it, but the polarization changes randomely with skywave propagation. Horizontal antennas seem to work a bit better overall as most noise is vertically polarized, so it ends up being a bit easier to "hear."

 

[Captain Kilowatt]

There will never be two IDENTICAL antennas with IDENTICAL "angles of attack"

Now if you have a vertical with a very low angle of attack (lets say 90deg for this discusion) and you are talking to a local station within 60 miles and they have a higher angle of attack (say 30 deg) but there are running the same power output and there antenna is " Identical"to yours in respect to gain. They will here you better than you will here them.

The reason being is that there signal has most of the RF density broadcasting upward toward the sky, versus yours where the majority of the RF density is being transmitted along the earths surface.

This same principal however does not work for DX. Once RF enters the atmosphere, the D and E regions as well as the others will "refract" the signal at verying degrees. So if the majority of your signal hits the atmosphere at lets say a 45 degree angel, it may exit at a 70 degree angle. Theres also other phenomenon to consider, like coastal ducting, Aura, Sparadic E, meteor reflection, and so on.

As a general rule of thumb The lower the angel of radiation, The further DX you will work.
And the Higher the angel of radiation, the closer dx you will work.

This also becomes null when considering what frequency you are refrencing. The higher the frequency the less effect the atmosphere will have.

I hope this isnt too confusing

Sorry but this part is wrong. An antenna has what is called reciprocity which means that it performs the same on receive as it does on transmit. This means that the signal lost due to high angle on TX is also lost on the receive end.IOW "his" high angle antenna also rejects signals from "your" low angle antenna because it is rejecting the signals arriving at a lower angle and enhancing the higher angle signals. It is for this reason that a simple 1/4 wave verticle will often outperform a yagi with fixed elevation mounting when working satellites.The higher gain of the yagi is more than offset by the poor performance of it at higher angles.

 

[C2]

QRN, that last part seems contradictory...


a simple 1/4 wave verticle will often outperform a yagi
The higher gain of the yagi is more than offset by the poor performance of it

Are you sure of this reciprocity?

An antenna has what is called reciprocity...

 

[Captain Kilowatt]

QRN, that last part seems contradictory...


a simple 1/4 wave verticle will often outperform a yagi
The higher gain of the yagi is more than offset by the poor performance of it

Are you sure of this reciprocity?

An antenna has what is called reciprocity...

100% positive.You cut off the bold area I highlited above. It says
"a simple 1/4 wave verticle will often outperform a yagi
The higher gain of the yagi is more than offset by the poor performance of it at higher angles. "
1/4 wave has a high angle of radiation that is aimed at the satellites better than the low angle of the high gain yagi. Both antennas exhibit a deep null directly overhead however. Also hams in mountainous areas with really high local repeaters have found that a simple 1/4 wave whip will outperform the higher gain 7/8 wave or collinear 2m/70cm antennas for the same reason. More of the signal is aimed upwards towards the repeaters rather than at the horizon. In Kansas somewhere the collinears and the 7/8 waves perform better.

Antenna reciprocity is the law of physics that says an antenna will exhibit the exact same characteristics for TX as it does for RX at any given frequency. The efficiency,gain and angle of maximum radiation (or reception) is the same for TX as it is for RX.
__________________

 

[dxhound]

100% positive.You cut off the bold area I highlited above. It says
"a simple 1/4 wave verticle will often outperform a yagi
The higher gain of the yagi is more than offset by the poor performance of it at higher angles. "
1/4 wave has a high angle of radiation that is aimed at the satellites better than the low angle of the high gain yagi. Both antennas exhibit a deep null directly overhead however. Also hams in mountainous areas with really high local repeaters have found that a simple 1/4 wave whip will outperform the higher gain 7/8 wave or collinear 2m/70cm antennas for the same reason. More of the signal is aimed upwards towards the repeaters rather than at the horizon. In Kansas somewhere the collinears and the 7/8 waves perform better.

Antenna reciprocity is the law of physics that says an antenna will exhibit the exact same characteristics for TX as it does for RX at any given frequency. The efficiency,gain and angle of maximum radiation (or reception) is the same for TX as it is for RX.
__________________

You are correct, what I meant to say was on a third party station, they would hear the lower angle of radiation antenna better than the Higher angle antenna, providing it too had a lower angle.

 

[ROC1]

Thanks for all the replies... this gets me thinking in some new directions.