[TowerTalk] Multi-band dipoles

[David Gilbert]

Sorry ...  I don't buy that.

1.  It can ONLY be quieter because of additional loss.  There is no 
other reason for it to be quieter since it has the same polarity and 
pattern as an equal length dipole.

2.  Without actually running a model, it would seem that any frequency 
that results in a current maximum at the resistor would have a lot of 
loss irrespective of what the SWR would be without the resistor.

Dave  AB7E


On 4/21/2011 7:31 PM, K3WRY at aol.com wrote:
> All interested hams:
>
> With many opinions about the B&  W folded dipoles, one needs to  understand
> the design and actual tested operations of this antenna design.
> It actually is quieter on receive, and the loss is only higher when the SWR
>   rises regardless any band or frequency operation.
> Therefore, if the SWR is kept low,  the transmitter efficiency of the
> antenna is actually measured, the actual radiated power can be very  high with
> minimal power being actually lost through the  resistor.
> The higher the SWR, the less efficient the antenna and consequently more
> power is lost through the resistor.
>
> Regards,
> Dr Joe Palsa
> k3wry
>
>
> No trees were destroyed in  the sending of this message, however, a
> significant number of electrons were  terribly inconvenienced
>
>
> In a message dated 4/21/2011 4:39:50 P.M. Eastern Daylight Time,
> steve at karinya.net writes:
>
> The  military love them because they value frequency agility over
> efficiency.
>
> Cebik's analysis put the power in the terminating resistor  at somewhere
> between half and 90% of the applied power, depending on the  band.
>
> 73,
> Steve G3TXQ
>
>
> On 21/04/2011 21:30, Grant Saviers  wrote:
>> I had one of these elevated resistors briefly in 1980.  It  was very very
>> quiet at both ends.
>>
>> Might be ok for  quick GOTA, emergency, or NVIS, that's what it seems the
>> military  wanted it for.
>>
>> Grant KZ1W
>>
>> On 4/21/2011 12:36  PM, David Gilbert wrote:
>>> By all accounts I've read, the B&W  folded dipole is indeed broadband.
>>> Since it has a relatively small  fixed "tuning network", that can only
>>> mean it has significant loss  relative to a normal dipole.  Estimates
>>> I've read vary  between one and two S-units.
>>>
>>> By all accounts I've  read, it is a "quiet" antenna on receive.  Since
>>> noise  rejection can only come from pattern or polarity discrimination
>>>   and the B&W antenna has no more of either of those than does a  standard
>>> dipole, that again means it has significant loss.   The antenna is
>>> probably just as quiet on the other end as it is on  yours.
>>>
>>> Dave    AB7E
>>>
>>>
>>>
>>>> From: "Fred  Serota"<fserota at msn.com>
>>>> Sent: Thursday, April 21, 2011  1:30 PM
>>>>   To:<jim at audiosystemsgroup.com>;<towertalk at contesting.com>
>>>>   Subject: Re: [TowerTalk] Multi-band  dipoles
>>>>
>>>>> Suggest trying Barker and  Willamson's folded dipole. They have three
>>>>> or 4 varieties,  some made of stainless wire for very tough climates.
>>>>> The  longest is approximately 120' and fives a flat SWR under 2:1  for
>>>>> 160-6 meters. Due to built in matching does not need a  tuner. This
>>>>> antenna has a special name, I have forgotten.  Can be ordered direct or
>>>>> I, thing, through HRO and  AES.
>>>>>
>>>>> Mine is hung as an inverted V and  works out very well.
>>>>>
>>>>> Fred,  K3BHX
>>>   _______________________________________________
>>>
>>>
>>>
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>>
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