[TowerTalk] Fw: Antennas for 80m

[Gene Fuller]

----- Original Message ----- 
From: "Gene Fuller" <w2lu at rochester.rr.com>
To: "Mike Fatchett W0MU" <w0mu at w0mu.com>
Sent: Saturday, April 23, 2011 8:05 PM
Subject: Re: [TowerTalk] Antennas for 80m


>A 43 foot vertical can be quite an effecient low angle radiator on 20 - 80 
>meters, IF it has a good radial system AND an effecient matching network. 
>For 80m, and somewhat less so for 40m, some top loading will raise the 
>radiation resistance, thus making it somewhat easier to design and build an 
>effecient matching network. In either case it probably would be best to 
>keep the resonante frequency, with the top loading, of not more than  .25 - 
>.375 wave, otherwise the vertical takeoff angle will start splitting up, 
>That is why the 43 foot vertical would not recommended for frequencies 
>above about 14 MHz. The same  principles apply to use on 160 meters. The 
>problem when you get down to 160 m is that the "radiation resistance" of 
>such a short (in terms of wavelengh) antenna is so low that its loss 
>resistance becomes quite significant relative to its radiation resistance 
>thus leading to a more inefficient radiator.
> There are many other implications along the way but this touches on some 
> of the basics.
> Gene / W2LU
>
> ----- Original Message ----- 
> From: "Mike Fatchett W0MU" <w0mu at w0mu.com>
> To: <towertalk at contesting.com>
> Sent: Saturday, April 23, 2011 3:00 PM
> Subject: Re: [TowerTalk] Antennas for 80m
>
>
>>I wasn't talking about the 43ft works everywhere, sorta, antenna.  I
>> believe they have a 80/40 offering.
>>
>> On 4/23/2011 11:31 AM, Tom Osborne wrote:
>>> I think I'd stay away from those '43 foot antennas'.  We had one of 
>>> those at
>>> FD last year and it didn't work all that well for 80.  You can make them
>>> load up, but don't think the efficiency is all that good.  73
>>> Tom W7WHY
>>>
>>>
>>>
>>> DX Eng might have some other 80/40 options too.
>>>
>>>
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