[Elecraft] Really OT: Inside-the-vehicle HF antennas (possible bonus points)

[Fred Jensen]

The Southern Pacific RR [now Union Pacific] used 160 MHz DDRR antennas 
on some of their signalling equipment. Generally on top of a big steel 
box beside the track(s).  Had a base plate bolted to the box, and a 
single 25-30 cm element, parallel to the top of the box, spaced about 
6-7 cm above it.  The whole antenna looked like it was cast in one 
piece.  For 20 m, it would be significantly larger, but might be 
disguised as, or in, a roof rack.  A lot of folks drive around with 
stuff piled on their cars these days.

http://www.orionmicro.com/ant/ddrr/ddrr1.htm has some design info

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 7/15/17 8:37 PM, Bob McGraw K4TAX wrote:
> Regarding the defrost heat element, there's two terminals, one on 
> either side.  However with the resistance of the defrost wiring in the 
> window, it might be more like a dummy load.  Of course one could just 
> feed one side against the auto body, unless one drives a Corvette 
> which is mostly plastic.   grrrr
>
> Seems I recall a DDRR antenna which was a low profile, roof mountable 
> antenna.   The 40M version would be a bit large with a diameter of 
> some 9 ft, although one might reduce the size and still make a 40M - 
> 10M of reasonable dimensions with reasonable efficiency.
>
> 73
>
> Bob, K4TAX
>
> K3S s/n 10163
>
>
>
>> On Jul 15, 2017 7:54 PM, "Wayne Burdick" <n6kr at elecraft.com> wrote:
>>
>>> I’m dealing with one of the last unsolved problems in amateur radio: 
>>> how
>>> to operate HF mobile without an antenna. At least not one that, 
>>> according
>>> to some vehicle co-owners/spouses, would defile your new sedan.
>>>
>>> For 10 bonus points that have only philosophical value, your 
>>> challenge is
>>> to create an invisible mobile antenna and actually make a QSO on it. 
>>> For
>>> practical purposes (i.e., not frying the car or passengers) let’s 
>>> say the
>>> maximum power level is 10 watts. The bands of interest are 40-10 
>>> meters.
>>>
>>> Here are some ideas I’m considering:
>>>
>>> - mag loop in the rear window
>>> - thin wire loop on a roof rack
>>> - gamma match to the entire roof
>>> - surface acoustic waves
>>> - prayer
>>>
>>> Other ideas?
>>>
>>> Yes, I know this violates the laws of physics and bioethics. And I 
>>> fully
>>> expect the car to generate debilitating levels of RFI. But isn’t 
>>> this the
>>> least you’d expect from an unsolved problem?
>>>
>>> Thanks in advance,
>>>
>>> Wayne
>>> N6KR
>>>
>>>
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