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Message |
    
Sdc1342
Junior Member
Username: Sdc1342
Post Number: 33
Registered: 12-2003
| | Posted on Saturday, April 11, 2009 - 1:59 pm: | 
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i am wondering if anyone has tried a groudplane kit on a 102 inch whip and if so the results? |
Barakuda318
Intermediate Member
Username: Barakuda318
Post Number: 199
Registered: 2-2002
| | Posted on Sunday, April 12, 2009 - 1:19 am: |
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well, if your trying to use the whip as a base antenna, then I would opt for the ground plane kit, but as for mobile operation there is no improving the 102" whip, they are simply the easiest and best antenna's to use for mobile operation in my book, when I hook them up mobile I use 18' of high quality coax, amphenol connectors and just the whip and almost always have flat swr's, only swings up a little when I'm next to buildings, and such, and that swing is hard to see, but if you are going to use it for a base antenna, then yes the ground plane makes sense as there is no vehicle to act as the ground plane... hope this helps.
73's Barakuda318
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Marconi
Advanced Member
Username: Marconi
Post Number: 804
Registered: 11-2001
| | Posted on Sunday, April 12, 2009 - 9:28 pm: |
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1342, the 1/4 wave needs a ground plane in order to work well at resonance. If you are talking about the A99 GPK, then you might find the radials too short for use with a 102" radiator. If you can get some more 102" whips, the setup will work even better for tune and resonance.
I use 6 radials, 3 horizontal and 3 slanted down. The hub is an A99 hub that is drilled for 6 radials as noted, and it works even better.
I sent you pictures via email, because my images are all too big for this forum's small image size requirements. |
Sitm
Intermediate Member
Username: Sitm
Post Number: 247
Registered: 1-2004
| | Posted on Monday, April 13, 2009 - 11:50 am: |
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I am actually kind of puzzled by this concept and would like to hear more about this so I can learn. So why doesn't an antenna such as a Antron 99 need radials but a 102 inch whip used as a base antenna does? If someone can explain this I would be appreciative. |
Inspector104
New member
Username: Inspector104
Post Number: 3
Registered: 12-2007
| | Posted on Tuesday, May 12, 2009 - 5:34 am: |
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The a-99 and Imax 2000 use an internal ground-matching network tuned by external rings on the base. It uses the grounding of the mast and the coax as the matched counterpoise or ground element. The addition of the A-99 Ground radial kit, just improves the physical ground-plane and improves the radiation angle to the horizon. I have made home-made 1/4wave antennas before and found that if your ground radials are bigger than your radiating element, the better- so I use three 104" elements when using a 102" vertical radiator. You could get away with a 102-104" single ground pointing down, opposite the 102" vertical. This is a true dipole...I have made emergency antennas out of just coax this way. |
Tech237
Moderator
Username: Tech237
Post Number: 1157
Registered: 4-2004
| | Posted on Tuesday, May 12, 2009 - 12:02 pm: |
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This a really good question, and one that, and one that many probably wish to know the answer to.
The A-99 doesnt need radials as it is really a half-wave end fed type of antenna. A properly designed half-wave antenna is it's own ground system.
The radials on a quarter wave antenna actually make it appear as if it is a full half-wave antenna. If you were to mount a 1/4 wave antenna directly on the ground, if may find no radials were needed as the ground would complete the "image" side to form the antenna - IF YOUR GROUND IS CONDUCTIVE ENOUGH.
Better explanations can be found in many books on antennas, but I hope this helps a little.
Simon
Tech237
N7AUS
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I thought he said, "there was no rust for the wicked, and I own an MGB"
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Bruce
Senior Member
Username: Bruce
Post Number: 5062
Registered: 9-2003
| | Posted on Tuesday, May 12, 2009 - 12:55 pm: |
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Just look at any 12 avq and you can see what needs to be done with a 1/4 wave antenna
On 6 since 66
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