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Author Topic: Is a counterpoise on a vertical for TX or RX or both?  (Read 3639 times)
WALTERB
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Posts: 528




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« on: April 16, 2012, 07:24:15 AM »



I’m wanting to install a 75m hamstick on my roof for RX only.  Do I need radials of some sort?

thanks
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KA3NXN
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« Reply #1 on: April 16, 2012, 07:49:50 AM »

It's for both. The hamstick portion of the antenna is only 1/2 of the whole antenna, the radials or counterpoise is the other half. You don't need it for listening, although it will hear much better with the counterpoise. You do need it for transmitting. The antenna won't tune without a good counterpoise. An absolute minimum of 4 radials cut for the band should do O.K. Still it's one heck of a severe compromise compared to a dipole.

Jaime-KA3NXN
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N3OX
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« Reply #2 on: April 16, 2012, 08:20:35 AM »

There will always always always be a counterpoise; if you don't supply one it will be the shield of your coax.

I would probably just use another hamstick and build a hamstick vertical dipole for 75m listening, maybe with a choke on the coax shield.  Without doing that it will hear fine if you have a very quiet house but the coax will probably pick up tons of noise from consumer electronics in the average house.  If you just connect a hamstick to the center conductor of your coax and tune it up it will be very much like using a random wire starting back at the rig where your coax is.  For some people that works fine, for many in the early days of ham radio it would have worked fine.  For many people in 2012 it would be a disaster.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W9GB
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« Reply #3 on: April 16, 2012, 09:01:01 AM »

Walter --

This is a common beginner question,
which I answer with a Common Sense style question (too make you think and learn basics).

An antenna is the LOAD for your RF (Electromagnectic Waves) generated by your Radio,
just like a Speaker is the load for an Audio Amplifier (Audio is also an EM wave).

You need TWO wires for the Speaker circuit to be complete --- Right?
Your speaker wire from amplifier is 2-conductor ...
The coax from your radio is 2 conductor ...  So you Hamstik antenna requires a return path ---radials/counterpoise.  Otherwise it really does not work well (or at all).

For receiving, you antenna is like the microphone that picks up sound.
It needs 2 wires, or you do not hear the announcer or musician!!!!

Feel like Homer Simpson, for missing this very basic principle?
Physics, How Things Work, are God's Rules of the Road (Universe) -- Gravity works whether you believe in the rules or not.
« Last Edit: April 16, 2012, 09:06:12 AM by W9GB » Logged
K9IUQ
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Posts: 2078




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« Reply #4 on: April 16, 2012, 09:05:02 AM »

Still it's one heck of a severe compromise compared to a dipole.
Jaime-KA3NXN

A properly installed vertical with radials is not a compromise at all vs a dipole. A vertical will outperform a dipole on DX.

The key IS radials, lots of them, the more the better. Most hams, especially newbies put up a trapped vertical 2ft from the garage or house, and run the ground to the conduit in the garage. Then they get on the air or eham and tell everyone how much verticals suck.  Wink

Stan K9IUQ
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WX7G
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« Reply #5 on: April 16, 2012, 10:15:38 AM »

Still it's one heck of a severe compromise compared to a dipole.
Jaime-KA3NXN

A properly installed vertical with radials is not a compromise at all vs a dipole. A vertical will outperform a dipole on DX.

The key IS radials, lots of them, the more the better. Most hams, especially newbies put up a trapped vertical 2ft from the garage or house, and run the ground to the conduit in the garage. Then they get on the air or eham and tell everyone how much verticals suck.  Wink

Stan K9IUQ

A dipole up 3/8 wavelength or higher will outperform a 100% efficient vertical for take-off-angles above 5 degrees. Here are the results of a NEC simulation for a 100% efficient vertical and a dipole up 3/8 wavelength. This is broadside to the dipole and ground is "average."

Take-off-angle (deg)   Vertical (dBi)    Dipole (dBi)
5                            -6.7                -6.4
10                          -2.8                 -0.8
15                          -1.2                  2.2
20                          -0.5                  4.0
30                          -0.3                  5.8
40                          -1.2                  6.1                  

We see that for "DX angles" the difference is small. But get that dipole up a bit higher and see what happens.
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AA4PB
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« Reply #6 on: April 16, 2012, 10:22:38 AM »

"A properly installed vertical with radials is not a compromise at all vs a dipole. A vertical will outperform a dipole on DX."

A properly installed 1/4 wave vertical yes, but he is asking about a 75M Hamstick. A Hamstick is a very short vertical with lots of loading coil and lots of loss on 75M. A 75M hamstick is probably not more than 5% efficient (even with the best radials) as compared to a full-sized 1/2 wave dipole mouinted at the same height.


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WALTERB
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« Reply #7 on: April 16, 2012, 11:25:24 AM »

Thanks.  It sounds like I should figure out a way to put up 1/2 dipole instead.  I'm not married to the idea of a hamstick. I just want something up in the air for RX only. 

thanks again!
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K9IUQ
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Posts: 2078




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« Reply #8 on: April 16, 2012, 12:00:08 PM »


We see that for "DX angles" the difference is small. But get that dipole up a bit higher and see what happens.


Tell that to the USA hams I stomp on in the pileups chasing DX on 40 meters. 4 years ago I put up a monoband 40 Meter vertical, homemade with 60 1/4 wave radials, mounted in the clear on my hill. At the time I had a "Mystery" antenna (so called because it is a mystery why anyone uses one) a 40 meter dipole, a 377 foot loop fed with open feeders. All the wire antennas were up around 50-60 feet. The ground mounted vertical outperformed all of them on nightly european QSOes and morning S.Pacific contacts. Also 90% of the time the vertical does better on CONUSA contacts. I have done literally over a hundred comparison tests in 4 years between my wire antennas and vertical. I know what works here on 40 mtrs, I do not need any eham smartass (who uses a screwdriver vertical -LMAO) doing modeling to tell me what works. Cheesy

This is not my only experiment with verticals. I have used verticals along with many many other antenna types for 52 years. I like them. Yep, I even tried a hamstick and a screwdriver vertical. Now they do suck......

Stan K9IUQ

« Last Edit: April 16, 2012, 12:02:11 PM by K9IUQ » Logged
WB6BYU
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Posts: 13574




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« Reply #9 on: April 16, 2012, 12:09:55 PM »

Quote from: WALTERB

...I just want something up in the air for RX only. 



A simple piece of wire connected to the antenna connector of your radio should pick up
plenty of signals on receive.  If you can run it across your roof and down to the radio
so much the better.  Even 30' of wire should work if that is all you can manage, but try
to at least run it across the roof and down to the radio.
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N4JTE
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« Reply #10 on: April 16, 2012, 02:32:32 PM »

K9IUQ, funny I have the complete opposite of your findings with averaging over 100 contacts every week for the last 10 years of comparisons on 40 DX and stateside nets. A single vertical has maybe been better sometimes but too few to remember.
Even phased verticals never outworked a pair of phased 45 ft high dipoles to date. All real time testing with both available at the same time.  Probaly a location thing !
Bob
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K9IUQ
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« Reply #11 on: April 16, 2012, 03:21:56 PM »

K9IUQ, funny I have the complete opposite of your findings  Probaly a location thing !
Bob

This is why I do not go by antenna modeling. I put them antennas up and check performance against antennas I already have. Screw the modeling and yes I have done more than my share of antenna modeling.

Antenna location and surroundings are perhaps more important than the antenna. With a vertical antenna, ground conductivity can be important, ever work them DXers using verticals by the salt water?  Cheesy Nearby objects affect antenna performance etc etc..

FWIW I live on a very high hill and my vertical is away from my house and other buildings. The ground slopes away from the vertical.....

Stan K9IUQ
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KF6A
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Posts: 215




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« Reply #12 on: April 17, 2012, 02:30:00 AM »

K9IUQ, funny I have the complete opposite of your findings with averaging over 100 contacts every week for the last 10 years of comparisons on 40 DX and stateside nets. A single vertical has maybe been better sometimes but too few to remember.
Even phased verticals never outworked a pair of phased 45 ft high dipoles to date. All real time testing with both available at the same time.  Probaly a location thing !
Bob
Is it possible your verticals weren't "optimally" installed?

This is why I do not go by antenna modeling. I put them antennas up and check performance against antennas I already have. Screw the modeling and yes I have done more than my share of antenna modeling.

Antenna location and surroundings are perhaps more important than the antenna. With a vertical antenna, ground conductivity can be important, ever work them DXers using verticals by the salt water?  Cheesy Nearby objects affect antenna performance etc etc..

FWIW I live on a very high hill and my vertical is away from my house and other buildings. The ground slopes away from the vertical.....

Stan K9IUQ
Is it possible your dipoles weren't optimally installed?

You both cannot be right, however, one of you can be wrong.
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KF6A
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Posts: 215




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« Reply #13 on: April 17, 2012, 02:43:19 AM »

I know on 40m at my current location my experiences with my vertical agree with Bob's assessment however I do not have a dipole to compare it to at this location. I also seem to be able to bust pileups on 40m easily and a lot of the time I don't even use my amp. It could be that the people I am competing against in the pileup are using low dipoles, I don't know, but there has to be a rational explanation since it isn't magic. From the west coast my shorty 40 worked very well and normally I was one of the first getting through the pileup, but with my low dipole that didn't hold true.

To address the OP, yes, if you want the best performance from your antenna it should be "properly" installed. But it will still "work" to some degree if it isn't. IMO, you're better off with putting up as much wire as you can, even if it isn't very high, rather than use an 80m hamstick whether you use radials or not. I sometimes connect my SDR to my short ground mounted beverage, which is just a wire laying on my lawn, and I am able to hear lots of activity on HF. The great thing about ham radio is you get to experiment with different things. Put something up and try it!
« Last Edit: April 17, 2012, 02:46:29 AM by KF6A » Logged
WX7G
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Posts: 6327




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« Reply #14 on: April 17, 2012, 06:01:32 AM »

I compared a 7 MHz inverted-vee at 32' against vertical having a good ground system. A-B testing revealed essentially no difference. These findings are confirmed by NEC modeling.

Note that this is broadside to the dipole/inverted-vee. Given a non-rotating dipole up 3/8 wavelength or less vs a vertical having a good ground system the dipole will be the equal of the vertical over only about 90 degrees out of a 360 degree circle.
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