[time-nuts] Re: Loop Antennas

[Alex Pummer]

Hi Bob,
that is my 60kHz remote receiver,
the remote tuning could be made relative simple, see the attached 
circuit diagram; by changing the supply voltage -- right to corner -- 
between 15V and 20V the tuning voltage for the varicaps  -- D8 and D9 -- 
will change between +1V and +10,5V, which causes 800pF capacitance 
changing the coil  L6 is approx 2,2mHy,
D6 an D7 prevent the damage Q25 gate, the op-amp circuit is matching the 
high impedance of the C108 L7 tank circuit to 50 ohm cable impedance. At 
the 20 long end of the cable -- with 50 termination -- I could see a p_p 
voltage  between 60mV and 500mV here in the Bay Area, in California, 
behind the wall, inside of the house, outside I could get at least 6dB more.
I am using that antenna for a frequency reference  --  a 10MHz PLL is 
locked to that 60kHz -- only just to verify that the output of the GPS 
is locked correct

73
KJ6UHN
Alex


On 6/7/2023 2:47 PM, Bob Camp via time-nuts wrote:
> Hi
>
> The next layer to this is that some (but not all) WWVB receiver designs appear to rely
> upon the “bandpass filter” of the antenna to provide reasonable rejection of “crud”.
>
> Having any sort of resonant circuit out in the back yard has implications. As the resonance
> shifts with temperature, so does the phase shift. At VLF phase is indeed a big deal. Just
> how big a deal …..
>
> As with a lot of things, you can indeed measure outside temperature and model this or that.
> Lots of fun can be had.
>
> Bob
>
>> On Jun 7, 2023, at 5:30 PM, Graham / KE9H <ke9h.graham at gmail.com> wrote:
>>
>> For WWVB time signals, I use a resonant ferrite rod antenna, but depending on the rod, the antenna bandwidth can be several hundred to several thousand Hz. Resonant multi-turn loops are likely to be similar.
>>
>> You will need a broad-band (non-resonant) loop for receiving Loran-C, due to the much wider modulation bandwidth of the signal.
>> --- Graham
>>
>> On Wed, Jun 7, 2023 at 3:46 PM Bob Camp via time-nuts <time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com>> wrote:
>>> Hi
>>>
>>> There are a number of sites around the web that go through the details
>>> of doing large-ish loop antennas for various LF signals. Are you trying to
>>> do something small (fit in your pocket) or something fairly large (10 foot
>>> diameter) ?
>>>
>>> Bob
>>>
>>>> On Jun 7, 2023, at 2:25 PM, JOHN HARTZELL via time-nuts <time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com>> wrote:
>>>>
>>>> Dear time nuts,
>>>>
>>>> Who has experience using loop antennas on the front end of receivers for receipt of Loran C, and other time signals?
>>>>
>>>> Kind regards,
>>>>
>>>> John
>>>>
>>>> https://linkedin.com/in/john-h-6a131b12/
>>>>
>>>>
>>>>
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