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Perfect height for 1/4 wave vertical.

Cody Dixson

Active Member
May 3, 2020
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If 11m is basically line of sight, and the fcc says a cb antenna can't be any higher than 60ft. Or 20 ft above the building or tree in which its mounted If i had an 80ft tall tree am I restricted to 60ft or would I be allowed 20 ft above tree?


The reason I'm asking this question is for a few reasons.

1. My current antenna sits at about 16ft above
the peak of my roof. Its a 102 steel whip no spring or riser. But the antenna is eye level with powerlines.
I have tall trees and I know if I could get above the power lines my noise level would cut down significantly.
2. I was told by an older fella that there are 3 levels of height that complement the cb band and from what he's saying im still in the first level. If any of this is smoke in your receive, I hear you!

Anyways any info is greatly appreciated!
73
 

Currently I have the antennas radials mounted at or as close to 45⁰ as possible. Tied off using parracord.

If I go higher. For the radials I thought I'd take some small aluminum tubing or pvc pipe and wire.
Attached to a mounting bracket all the radials will set at 45⁰. Mfj and others like sirio make similar base style antennas with this design. @sp5it
 
s-l400.jpg

I thought this might be the best radial set up for the 102 whip. @sp5it

My main question is if my trees are higher than 60 ft am I allowed to go above 60ft or am I restricted to a max height of 60ft for the 11m band
 
Download mmana, use this data and check what height will be fine for you. I would go for 25m
GP with slope radials
*
27.20
***Wires***
4
0.0, 0.0, 0.0, 0.0, 0.0, 2.64333, 0.01, -1
0.0, 0.0, 0.0, 2.38157, 0.0, -1.32167, 0.01, -1
0.0, 0.0, 0.0, -1.19078, 2.0625, -1.32167, 0.01, -1
0.0, 0.0, 0.0, -1.19078, -2.0625, -1.32167, 0.01, -1
***Source***
1, 0
w1b, 0.0, 1.0
***Load***
0, 1
***Segmentation***
400, 40, 2.0, 2
***G/H/M/R/AzEl/X***
2, 30.0, 0, 50.0, 120, 60, 0.0
 
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Reactions: Cody Dixson
@BJ radionut well shoot if thats the case imma send it up as high as I can get it, or untill the city can spot it from town hall. Lol I learn new stuff every day about this hobby. I thought the height restriction was for the band itself didn't know it was a restriction on the operator. Thanks for the heads up!!!
 
https://static.dxengineering.com/global/images/instructions/dxe-va-base_ig.pdf

See figure #2 and #4 specifically

Cody: I offer this as an example of possible construction of the antenna your going to raise.
The larger diameter of the tubing (vs. steel whip) tends to make the antenna cover a larger frequency range. (overall bandwidth)
You can then build this antenna to cover both the 10 and 11 meter band with "usable" VSWR. You can then tune the antenna for the bottom of the 10 meter band. (28.0)
The larger diameter of the tubing (ex.: 1 1/2 inch OD) as a starting point, will tend to "widen" the frequency range the antenna will operate effectively.
I built my homebrew 10 meter antenna using that size as a base, then added short sections that telescoped down in size. I overlapped the sections so that I had easily a foot of tubing inside each section. This made the antenna very strong.
However, by doing this the antenna covered the entire 10 meter band (28.0 thru 29.5) with a VSWR of less than 1.6:1.
The interesting point is this, by tuning the antenna to resonance at 28.0. ( I was shooting to optimize the CW range) I found out when sweeping the antenna with my analyzer that the VSWR of the antenna was less than 2.0 :1 all the way down to the top end of the 11 meter band. (VSWR@ 27.350).
I had a usable antenna with the radio's internal tuner, (or external manual tuner) that would cover BOTH bands nicely.
I should note I have not been on the 11 meter band in a VERY long time.
I do though have the ability to do so if I wished.

Note: The statement I made regarding antenna height is this.
The 60 foot limit on antenna height for the 11 meter band is a rule. However, as pointed out it is not enforced.
The antenna height restriction for the US Amatuer Radio operator is 200 feet (unless living next to an airport runway system).
That said, if at some point an "inspection" by FCC was to ever occur:D your "10 meter" antenna is in compliance at whatever height it resides.:whistle::ROFLMAO:
Enjoy, many here to help.
All the Best
Gary/W9FNB
 
Blackcat: You may be actually correct. The antenna structure can exceed 200 feet. The FAA and FCC then adds multiple extra provisions. Hence, most US Amateurs' "elect" to stay with-in the 200 foot range, to avoid the extra provisions.
Yes, these can involve "outside Engineering requirements" involved in not only design, installation, maintaince, registry and FAA compliance. BIG $$$$
Hence many towers are "identified" as 196 feet when installed.(y):ROFLMAO:
I will never be concerned with any of those, as 99% of US amateur's.:LOL:
I do have a private airfield less than a mile away, however the single runway is turned away from my location.
I had antennas at one time, that extended the 100 foot level at the top. The orientation of the runway, and the fact that the minimum 500 foot flight limit over the town never justified any registry etc.(y)
This is no longer the case, as I have stated before Hurricane IKE in the late 90's took care of that structure.:cry:

Sounds like the 6 meter band trying to OPEN...or some very good sustained meteor bursts occurring. Time to make some NOISE!!!
Later 73

All the Best
Gary/W9FNB
 

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