• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

The Myth Surrounding Antenna Take Off Angles

W5LZ

Crotchety Old Bastard
Apr 8, 2005
6,832
888
173
Oklahoma
"... that was placed in a free space ( nothing in the first and second Fresnel Zone )..."
By definition, a fresnel zone can't be in 'free space', bad description there...
- 'Doc
 
  • Like
Reactions: 1 person

Onelasttime

Sr. Member
Aug 3, 2011
1,142
715
123
Well no matter what the hobby be it amateur radio, target shooting, or playing the trumpet there will always be a subset in each group that has to take things to the extreme. Sometimes you have to wonder if they even like talking on the radio because they spend more time fussing over gear than actually talking on the gear!

I am-not immune to this myself. I have spent more time than I care to admit trying to figure out the perfect barrel dimensions, load parameters, barrel materials etc.... Far more time than I actually spend on the range.

For some people fussing over antenna details and coax and other such things might be more fun than talking on the radio but building an antenna is pointless with out a radio so the radio hobby is just their to feed their desire to build things and exercise their mind's analytical side!

I tend to be the opposite! I do like to talk about such things but I would rather talk on the radio than be stuck in my basement or garage building an antenna or tweaking the radio itself. All of that is good stuff but for me the real fun is talking on the air all the other stuff is secondary.

I also think that a lot of men today need more drama in their lives than they did years ago and forums like this and polarizing topics provide that drama. It is not as if you can go down to the pub on the corner and talk about antenna's! LOL

P.S. Thanks for the technical tutoring I love learning new things and the finer details of old things! Great post!
 

rabbiporkchop

Sr. Member
Jan 18, 2007
1,830
761
123
pennsylvania
The one on the left is 4 feet long and the one on the right is 7 ft long. Which one has a lower take off angle?
1512673798126.png
 

The DB

Sr. Member
Aug 14, 2011
2,008
1,536
193
St. Louis, MO
The TOA is determined mostly by where the current node is and how high it is above the earth. On all 1/4 wavelength antennas, including shortened 1/4 wavelength antennas like these the feed point is where the current node is. Because of this, if these antennas are mounted on identical mounts, they will have the same take off angle. If one is mounted higher than the other, the higher antenna will have the lower TOA.


The DB
 

Flatop

Active Member
Apr 12, 2019
50
37
28
51
With all the 11 meter antenna's I have ever used, the ones that worked the best - with the crappy AM / SSB CB radios was the antenna's that was placed in a free space ( nothing in the first and second Fresnel Zone ) somewhere between 30 and 60' in height.

I know this is an old post, but what's with the continual criticism of CB radio? A few posts here ridicule that CBers seem to think they can elude physics. This post is hypocritical as he mentions 'crappy cb radios'. I don't see what this has to do with it, the discussion is about take of angle. The radio is a constant so it doesn't matter what you are using to test the theory. The CB thing is irrelevant and this should not be a forum for degrading all CB radio operators when ever you feel like it.
 
  • Like
Reactions: Shadetree Mechanic

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
3,430
1,321
173
I will throw my 2 cents in.
Most CB radios are crappy compared to other options of transceivers.
Some 11 meter rigs are definitely better than others.

What is the use of understanding take off angles if the radio you are using can not hear the weak signals?

No one is dishing on CBers as most of the members here enjoy all types of communications.
You only quoted part of the post, the rest of the post he explained the general progression of antenna improvement and height vs operating requirements wither local or DX,
Any questions re read the post you quoted in its entirety.
 

Shockwave

Sr. Member
Sep 19, 2009
3,785
3,301
273
There is nothing I can hear on my Kenwood or Yaesu that I can't hear on my Tram or Browning in the 11 meter band. The HF rigs have better selectivity but their sensitivity is not noticeably better and with 10 KHz. channel separation, selectivity is not nearly as critical on 11. I'll also mention I've never seen a noise blanker on an HF rig work as well as it does in a narrow band receiver like a Cobra. You have to turn it up for a weak signal and off for strong ones or it distorts the signal. You would think one of the HF manufacturers could tie the NB in with the AGC so that it automatically reduced blanking on strong signals. Then my NB switches wouldn't wear out.
 
Last edited:

Flatop

Active Member
Apr 12, 2019
50
37
28
51
I will throw my 2 cents in.
Most CB radios are crappy compared to other options of transceivers.
Some 11 meter rigs are definitely better than others.

What is the use of understanding take off angles if the radio you are using can not hear the weak signals?

No one is dishing on CBers as most of the members here enjoy all types of communications.
You only quoted part of the post, the rest of the post he explained the general progression of antenna improvement and height vs operating requirements wither local or DX,
Any questions re read the post you quoted in its entirety.
I don't have to quote the entire post, the radio you are using has nothing to do with it, that's why I said it is a constant.
 

Flatop

Active Member
Apr 12, 2019
50
37
28
51
And Wavrider, here are two quotes from two other separate posts in this thread alone. They are rather sarcastic.

'Oh boy. There you go again, tilting at our 11M windmills.
You said it yourself in another post, something like "Normal laws of physics don't apply in the 11M band" :laugh:'

And...

'Thats a cool read but :oops: remember this doesnt apply to citizens band LMA:LOL:!!!!'
 

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
3,430
1,321
173
http://www.rigpix.com/kenwood/ts440s.htm
Kenwood specs old ts 440
https://www.cnet.com/products/cobra-29-ltd-classic-cb-radio/
cobra 29 specs

Sensitivity is different??
On SSB there is a big difference.
Once again comparing apples to oranges.
I do agree the brownings have a great receive, especially if one knows how to increase the gain in the If sections. my Browning Eagle and Mark II can hear a gnat fart three counties away.

As far as sarcasm?, last I remember this is a radio forum, ALL the ham bands and 11 meters are full of sarcasm, what makes you think that an online forum dedicated to the hobby would be any different?
 
Last edited:
  • Like
Reactions: LeapFrog

AudioShockwav

Extraterrestrial
Staff member
Apr 6, 2005
7,969
6,386
593
Nor Cal Sierra Nevada
Flat top the CB vers Ham radio stuff never ends well.
Everyone is entitled to a opinion.
Sometimes on internet forums you need a little thicker skin to allow others to post there opinion with out getting butt hurt.
I guess I could point out that this is the Amateur section of the forum but most of us manage to get over it with out being too anal about it.
It has worked well over many years.....
Try to lighten up and just enjoy the forum.

73
Jeff
 

Shockwave

Sr. Member
Sep 19, 2009
3,785
3,301
273
http://www.rigpix.com/kenwood/ts440s.htm
Kenwood specs old ts 440
https://www.cnet.com/products/cobra-29-ltd-classic-cb-radio/
cobra 29 specs

Sensitivity is different??
On SSB there is a big difference.
Once again comparing apples to oranges.
The 29 doesn't have SSB to compare against but lets look at the 148GTL here: https://www.universal-radio.com/catalog/cb_radio/4634spec.html
Notice they both have exactly .25uv sensitivity for a 10db signal to noise ratio on SSB? You may be surprised to see the AM sensitivity is more on the 148GTL than the TS-440S too.
 

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
3,430
1,321
173
If you would like you can start another thread and we can copy and paste specifications for radios. ;)
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
17,041
11,552
823
59
Nova Scotia,Canada
Flat top the CB vers Ham radio stuff never ends well.
Everyone is entitled to a opinion.
Sometimes on internet forums you need a little thicker skin to allow others to post there opinion with out getting butt hurt.
I guess I could point out that this is the Amateur section of the forum but most of us manage to get over it with out being too anal about it.
It has worked well over many years.....
Try to lighten up and just enjoy the forum.

73
Jeff

If this were in the CB section of the forum it is where someone would jump in and say that if hams didn't like what they read they should stay out of the CB forums and refrain from commenting in them however we won't do that as everyone is welcome but they should be prepared to hear things that they do not agree with since this section deals more with reality than it does perception when it comes to technical aspects.
 

dxChat
Help Users
  • No one is chatting at the moment.
  • @ BJ radionut:
    We have a pronounced focus on human modes:ROFLMAO::cool:
  • @ BJ radionut:
    There will be NO FT8 robots running unattended at Bouvet,:ROFLMAO:
  • @ BJ radionut:
    10M BAND.....>28400 SSB .... Always give your full callsign. Listening is the key so be sure we call you before replying. 3Y0J will always listen up (using split) so it will be useless to call us on our transmission frequency.
  • @ BJ radionut:
    I like these guys already. :cool: Sounds to me like ROBO callers in ANY Mode will be ignored!!!!(y)