| Author |
Message |
    
Dale
Senior Member
Username: Dale
Post Number: 2335
Registered: 12-2002
| | Posted on Saturday, April 14, 2018 - 4:33 pm: | 
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i know what the antenna hand book says the centerload is better then base and top is better.
take for example wilson 1000 base load and wilson 2000 trucker. the trucker with a 10 inch shaft is 3 inches shorter than the baseload 1000.and the 2000 has a whip 10 inches shorter.now ive also heard its about having the coil elevated above the roof as opposed to havin it sitting on or nea the roof.whats everyones take
dale/a.k.a.hotrod
cef426
cvc#64
454 [dx numbers]
38lsb
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Tech833
Moderator
Username: Tech833
Post Number: 2404
Registered: 8-2002
| | Posted on Sunday, April 15, 2018 - 1:53 am: |
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What the antenna book doesn't fully explain is 'why'.
In fact, in some cases, a base loaded (loaded 1/4 wave) antenna can outperform a top loaded antenna. Why? Because of takeoff angle and radiation efficiency.
Over perfect ground, a top loaded antenna can outperform a base loaded antenna. However, there is no such thing as perfect ground in a mobile environment. The base loaded antennas work better over a less than ideal ground plane. Also, it is easier to achieve a perfect 50 ohm, zero reactance match with a base loaded antenna by tapping the coil (like the Wilsons do) or adding components to the feedpoint (like the K40 does).
Your radio 'Mythbuster' since 1998
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Dale
Senior Member
Username: Dale
Post Number: 2336
Registered: 12-2002
| | Posted on Sunday, April 15, 2018 - 8:27 am: |
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thank you tech 833. what about the centerloaded trucker serires with an elevated coil?given mounting locations were in same spot
dale/a.k.a.hotrod
cef426
cvc#64
454 [dx numbers]
38lsb
|
Tech237
Moderator
Username: Tech237
Post Number: 1915
Registered: 4-2004
| | Posted on Monday, April 16, 2018 - 9:02 am: |
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Also take into account, it is often easier to build a mechanically strong Base loaded antenna than it is to make a mechanically strong center or top loaded one.
Tech237
N7AUS
God made me an athiest, who are you to question his wisdom?
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Tech833
Moderator
Username: Tech833
Post Number: 2405
Registered: 8-2002
| | Posted on Wednesday, April 18, 2018 - 1:34 am: |
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Hi Dale,
Center loading and top loading are nearly identical in characteristics.
In the article "Big Coil Antennas Exposed", you can see that base and center loaded antennas on the same imperfect ground work about the same.
Your radio 'Mythbuster' since 1998
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Dale
Senior Member
Username: Dale
Post Number: 2337
Registered: 12-2002
| | Posted on Saturday, April 21, 2018 - 1:49 pm: |
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thanks guys
dale/a.k.a.hotrod
cef426
cvc#64
454 [dx numbers]
38lsb
|
