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 The Importance of Antenna Height 
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Post The Importance of Antenna Height
The Importance of Antenna Height
We all know that the height of an antenna is important, but we may not know how important and all the reasons and benefits it can bring. Also there are some points to watch as well as the antenna rises higher above the ground.

Ian Poole of Electronics Notes has just released a video showing how antenna height at VHF and UHF brings some significant benefits for professional radio and broadcasting as well as amateur radio.

The benefits are significant and warrant many antennas being located in high positions and on high towers, but this all comes at a cost.

Find out what you need to know in this video
https://youtu.be/UvfAkcsi9Qg

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Wed Mar 09, 2022 8:57 am
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 The Importance of Antenna Height 
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Post Re: The Importance of Antenna Height
A clear, concise and well presented overview. In general I agree with the points made, however in my situation being in a valley, maximum height is not always important and can be detrimental!

Knife-edge diffraction can play an important part for me on VHF. I did some experiments on 4m with a vertical omni on a 12m mast. My maximum signal strength received by a station 10 miles away was not at full extension but with the mast at 8m. Presumably hitting an optimum which could be visualised as something like the patterns on the Japanese flag.

Many signals I receive are not on a direct path & I have to beam to hillsides to get a reflection. For example to work Devon on 70cm I should beam South but I can only work there by beaming West. My antenna height makes no great difference with these reflections.

The hillside that I am on presents a significant barrier to the East on VHF/UHF yet is my best direction on 10GHz! I work Taunton at 130km every day, I have 12W to 1m dish that is on a 9m mast.

Whether the mast is extended at all makes no difference (other an elevation tweak) as the mast height is insignificant in comparison to the the height of my hill & the hill beyond that. What I am aiming at is not an obvious horizon but into the troposphere and my antenna height makes no difference.

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G8ADP in 1964 then G4MBS in 1981 for CW on microwaves esp 10GHz tropo/rain scatter. QRT for 33 years. Moved to GW in 2016 pottering on 6m - 3cm seeing what can be achieved from down in a valley where any QSO is a triumph of optimism over geography!


Wed Mar 09, 2022 9:40 am
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 The Importance of Antenna Height 
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Post Re: The Importance of Antenna Height
GW4MBS wrote:
A clear, concise and well presented overview. In general I agree with the points made, however in my situation being in a valley, maximum height is not always important and can be detrimental!

Knife-edge diffraction can play an important part for me on VHF. I did some experiments on 4m with a vertical omni on a 12m mast. My maximum signal strength received by a station 10 miles away was not at full extension but with the mast at 8m. Presumably hitting an optimum which could be visualised as something like the patterns on the Japanese flag.

Many signals I receive are not on a direct path & I have to beam to hillsides to get a reflection. For example to work Devon on 70cm I should beam South but I can only work there by beaming West. My antenna height makes no great difference with these reflections.

The hillside that I am on presents a significant barrier to the East on VHF/UHF yet is my best direction on 10GHz! I work Taunton at 130km every day, I have 12W to 1m dish that is on a 9m mast.

Whether the mast is extended at all makes no difference (other an elevation tweak) as the mast height is insignificant in comparison to the the height of my hill & the hill beyond that. What I am aiming at is not an obvious horizon but into the troposphere and my antenna height makes no difference.


Very interesting - thanks

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Sat Mar 26, 2022 8:31 pm
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 The Importance of Antenna Height 
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Post Re: The Importance of Antenna Height
GW4MBS wrote:
A clear, concise and well presented overview. In general I agree with the points made, however in my situation being in a valley, maximum height is not always important and can be detrimental!

Knife-edge diffraction can play an important part for me on VHF. I did some experiments on 4m with a vertical omni on a 12m mast. My maximum signal strength received by a station 10 miles away was not at full extension but with the mast at 8m. Presumably hitting an optimum which could be visualised as something like the patterns on the Japanese flag.

Many signals I receive are not on a direct path & I have to beam to hillsides to get a reflection. For example to work Devon on 70cm I should beam South but I can only work there by beaming West. My antenna height makes no great difference with these reflections.

The hillside that I am on presents a significant barrier to the East on VHF/UHF yet is my best direction on 10GHz! I work Taunton at 130km every day, I have 12W to 1m dish that is on a 9m mast.

Whether the mast is extended at all makes no difference (other an elevation tweak) as the mast height is insignificant in comparison to the the height of my hill & the hill beyond that. What I am aiming at is not an obvious horizon but into the troposphere and my antenna height makes no difference.

It's these vagaries that make VHF, and up, so interesting.
To work one local, on 13cm, despite him being 60km South East of me the best result is when he beams at the Wrekin - South of him.
To work EI - to the West - it's often better to beam East and use backscatter.
Reflective paths are often better than direct.
A path profile between us doesn't look promising but we've worked many times on 4/6M, and even on 70cm.
Interestingly, not on 2M.
I don't know exactly where you are so the calcs are done from the centre of the square.
I find a relatively small error in location can make a big difference in the reliability of the calcs.
even with a relatively clear take off, to the East, I find that height often doesn't have the effect you would expect.
I imagine reflections, and knife edge refractions are behind this.

Cheers

Tony

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Sun Mar 27, 2022 6:50 pm
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 The Importance of Antenna Height 
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Post Re: The Importance of Antenna Height
I'll forwarded the link to a few locals. I've lost count of the number of People who complain that they're not getting out using a white stick antenna attached to the gable end of their garden shed.


Mon Mar 28, 2022 6:46 am
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