if ou are thinking of using your fence as an antenna you have one issue that may or may not be a real problem. because the chain and associated hardware isn't electrically bonded, you can get poor contacts, or even semi conductive contacts with corrosion and can generate rfi . having coorsion and semiconductors, the signal you transmit can excite the those areas and cause them to re adioate and generate harmonics. you also have the issue that most fences of this type are grounded as well, so matching it would be very difficult
so be careful and if you decide to use the fence as an antenna, make sure you check for harmonics and tvi or rfi good luck
kb7nla
On Nov 22, 2010, at 5:07 PM, Junior Lolley wrote:
> Colin, that is an idea I have a 6 foot chain link fence.
> It is 468 foot long.
> Thanks much.
>
>
> Junior Lolley KG4ITD Liberty County E. C.
>
>
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of colin McDonald
> Sent: Monday, November 22, 2010 4:00 PM
> To: [log in to unmask]
> Subject: Re: nvis antenna
>
> try getting the antenna say 5 feet above the top rail of the fence. the
> metal top pipe rail will act as a paracytic element and may give you even
> better results with an NVIS antenna.
> as long as you can get a good 65, or better, 130 feet out of it.
> 73
> Colin, V A6BKX
> ----- Original Message -----
> From: "Gerry Leary" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, November 22, 2010 6:07 AM
> Subject: Re: nvis antenna
>
>
>> This is new information for me. I haven't been following this thread, but
>
>> I
>> might actually try it. My fence is a Metal chain link kind, but I could
>> clamp plastic pipe on the support poles and hang the antenna from that.
>> Do
>> you think the fence will absorb the RF, and How far above the Fence do you
>> think I should keep it? Gerry
>> ----- Original Message -----
>> From: "Junior Lolley" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Saturday, November 20, 2010 2:21 PM
>> Subject: Re: nvis antenna
>>
>>
>>> Colin, thanks much well it looks like I will have to lower the antenna a
>>> little bit.
>>>
>>>
>>> Junior Lolley KG4ITD Liberty County E. C.
>>>
>>> -----Original Message-----
>>> From: For blind ham radio operators
>>> [mailto:[log in to unmask]]
>>> On Behalf Of colin McDonald
>>> Sent: Saturday, November 20, 2010 4:05 PM
>>> To: [log in to unmask]
>>> Subject: Re: nvis antenna
>>>
>>> it'll depend on which bands you wish to work NVIS on.
>>> Typically, 160 and 80/75M are the usable NVIS bands.
>>> You want your main radiating wire down pretty low, say between 5 and 15
>>> feet
>>>
>>> off the ground. It has to be in a horizontal configuration. Some guys
>>> will
>>>
>>> put another wire along the ground as a paracytic element. A dipole at
>>> 30FT
>>> will have some NVIS properties, but not like something that is 8 or 10
>>> feet
>>> off the ground.
>>> One of the best antennas I ever built was an 80M NVIS wire. essentially
>>> just a piece of 14 gage copper wire strung in a large U shape around a
>>> fence
>>>
>>> line. I made the wire about 68 feet long, connected the center conducter
>>> of
>>>
>>> a coax to one end, and the ground of the coax to a cold water pipe that
>>> went
>>>
>>> straight into the ground near the feed point. The antenna was no more
>>> than
>>> 5 feet off the ground. I cut about 6 inches at a time off the far end
>>> from
>>> the feed point until I obtained a 1 to 1 match at 3.750. The final
>>> length
>>> was probably around 65 feet. The U was approximately 20 feet per side,
>>> with
>>>
>>> the longer leg being 25 feet long...the one that came back towards the
>>> feed
>>> point was the long side, that is, on the opposite side of the you...so
>>> the
>>> end of the antenna was actually about 5 feet back past the feet point,
>>> but
>>> 20 feet across the yard...this was a duplex back yard so there wasn't
>>> much
>>> room for an antenna. I just layed the wire on the top rail of the wooden
>>> fence and used large staples to keep it from blowing off.
>>> That antenna would consistently perform very well out to about 1200 miles
>>> in
>>>
>>> any direction, and more often than not could talk and hear into ontario,
>>> about 2500 miles to the east. It was a great NVIS antenna and the
>>> signals
>>> within that 1200 miles were almost always S9 and above...that is the
>>> great
>>> thing about NVIS antennas. they perform extremely well for what they are
>>> designed to do.
>>> Now, if that antenna had been up at 30FT, I don't think it would have
>>> performed as well.
>>> regards
>>> Colin
>>>
>>> ----- Original Message -----
>>> From: "Junior Lolley" <[log in to unmask]>
>>> To: <[log in to unmask]>
>>> Sent: Saturday, November 20, 2010 4:39 AM
>>> Subject: nvis antenna
>>>
>>>
>>>> I have a 132 foot dipole I want to use for NVIS.
>>>> I have sandy soil here in Florida.
>>>> What is the best height off the ground to have each end?
>>>> It is 30 foot center on the tower.
>>>> I now have each end about 10 foot off the ground.
>>>> I am trying to mess around with NVIS a little bit.
>>>> if anyone can give me a little info it would help.
>>>> Thanks very much.
>>>>
>>>>
>>>>
>>>> Junior Lolley KG4ITD Liberty County E. C.
>>>
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