[time-nuts] Smaller, and smaller antennas

[jimlux]

On 3/5/19 3:05 PM, Charles Steinmetz wrote:
> Ho, hum, yet another fantastical claim for magical gain from a 
> tiny-for-wavelength antenna.
> 
> See the many discussions of same by Kurt N. Sterba over the last several 
> decades, among many, many others.
> 
> The laws of physics are stubborn things....


these don't violate the theoretical limits.. 100 MHz BW at 2.4 GHz is 
pretty high Q (240).

What I'm interested in is the internal construction -  lambda at 2.4 GHz 
is 122 mm, and these things are 3x3x4mm.  If you tried to dielectrically 
load a half wavelength from 61 down to 3mm, that's a factor of 20, which 
implies an epsilon of 400.  Clearly, that's not what they're doing.

I'm a bit suspicious about that long feedline in the test fixture.


Johansen has lots of these in various frequencies and sizes
https://www.johansontechnology.com/antennas

Tons of WiFi (2.45 GHz) antennas in all sizes and shapes.

GPS/GLONASS antennas too
https://www.johansontechnology.com/datasheets/1575AT54A0010/1575AT54A0010.pdf
12x4mm




> 
> Best regards,
> 
> Charles
> 
> 
> On 3/5/2019 1:48 PM, jimlux wrote:
>> On 3/5/19 9:33 AM, Gregory Beat via time-nuts wrote:
>>> No, this is not an “L-band”, GNSS antenna ... BUT it demonstrates the
>>> shrinking size.
>>>
>>> NEW Molex 206513 Antenna for 2.4 GHz, 3x3x4 mm in size.
>>> Less than $1.00 for quantity 1, both Mouser and Digi-Key now stocking.
>>> https://www.digikey.com/en/product-highlight/m/molex/2-4-ghz-ceramic-antenna 
>>>
>>>
>>>
>>> Molex’s 206513 series is a 2.4 GHz embedded ceramic antenna with high
>>> efficiency over 55% on all frequency bands. This miniature SMT ceramic
>>> component requires a very small (4 mm x 4 mm) keep-out area and is
>>> designed to be mounted directly at the corner of the main device PCB.
>>> It has a frequency range of 2.4 GHz - 2.5 GHz, return loss of <-6 dB,
>>> and peak gain (max) 3.6 dBi. It features an omnidirectional radiation
>>> pattern.
>>>
>>
>> One needs to carefully look at the 55% claim with these kinds of things.
>>   Are they including that in the gain, 50% efficiency is a gain hit of
>> 3dB? Peak gain of 3.6dBi (is that circular or linear?) (is that
>> directivity, or gain?). Does the efficiency count the 25% of the power
>> reflected back from the 6dB return loss?
>>
>> https://www.molex.com/pdm_docs/ps/2065130001-PS.pdf is more about 
>> packaging
>>
>> https://www.molex.com/pdm_docs/as/2065130001-AS.pdf has the antenna
>> patterns..
>>
>>
>>
>> Also, what's the axial ratio off boresight...
>>
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