> and the loss is only higher when the SWR rises regardless any band
> or frequency operation.
That is demonstrably incorrect as shown by a multitude of analysis.
The terminating resistor is in series with the radiating element and
results in a minimum loss of 3dB just like any other terminated
"broadband" antenna.
Most reputable (commercial) manufacturers of the terminated folded
dipole for military/government service give "gain" specifications
ranging from -1 to -4 dBi in free space and efficiency ratings of
15% to 50% (30% average). Such performance is equivalent to turning
1 Kw to 250 watts ... or a barefoot 100 W rig into a 25W pea whistle
on most bands (and even worse on 160 or 80 meters depending on the
antenna size).
While such performance may be fine for military/government use with
frequency agile, high power ALE circuits, or in short range NVIS
applications, the terminated folded dipole belongs in the same
category as the Isotron, cross-field, and fractal antennas for
amateur purposes.
73,
... Joe, W4TV
On 4/21/2011 10:31 PM, K3WRY@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@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@msn.com>
>>>> Sent: Thursday, April 21, 2011 1:30 PM
>>>> To:<jim@audiosystemsgroup.com>;<towertalk@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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>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>> _______________________________________________
>>
>>
>>
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