[VicPiMakers Projects] Fwd: a couple of quick questions

[James Briante]

Hi Dave,

Reflected power (that can cause damage) occurs when the antenna
resonant frequency does not match the frequency of the transmitting unit.
HAM radio operates on many different bands, so is the custom to place an
antenna tuner between the Antenna and the transmitter to match the
impedance (newer radio ham transceivers have built-in antenna turners). I
have both but my antenna tuner does not operate at the LoRa frequency. I
would not bother trying to build a homemade Lora antenna. Decide what
antenna gain (DBi) you require and  purchase one at amazon.ca.  Stubbies
are relatively cheap (2DBi, $13) with prices going ains for pole mounted
high gain ones.

Jim

On Thu, Apr 14, 2022 at 4:33 AM Deid Reimer <deid at drsol.com> wrote:

> Hi Dave,
>
> I don't have a spectrum analyzer, although it is on my list of things to
> acquire soon.
>
> A couple of videos worth watching on building antennas.   The bottom line,
> if you build it to specs the vswr should be acceptable.
>
> https://youtu.be/eQEmFlMW50o
>
> https://youtu.be/6cVYsHCLKq8
>
>
> Deid
> va7rei
> On Apr. 13, 2022, at 10:25 p.m., George Bowden <gtbowdeng at gmail.com>
> wrote:
>>
>> Hi Dave.  I've forwarded your query to the projects group.   That is the
>> best place to get a response, where more people can see it...
>> I dont think a spectrum analyser is needed.  You could attach a dipole of
>> the right length, depending on the frequency you choose for the lora .  at
>> 915 mhz it could be made from a couple pieces of copper wire, attached with
>> a uFL to the lora module, if that is what it has...
>> https://www.omnicalculator.com/physics/dipole is a dipole calculator,
>> which says two wires each 16.4 cm long would make a dipole.
>> Deid is the one to answer antenna questions...  He's a ham operator.
>>
>> ---------- Forwarded message ---------
>> From: Dave Gates <dbgates at gmail.com>
>> Date: Wed, Apr 13, 2022 at 8:52 PM
>> Subject: a couple of quick questions
>> To: George Bowden <gtbowdeng at gmail.com>
>>
>>
>> Hi George,
>>
>> First: does anyone in the group have a spectrum analyzer?
>>
>> The antenna with the LoRa modules looks like the recommended one (as per
>> the video you sent me) but I have no way of knowing for sure... the
>> video mentioned that if enough of the power sent to the antenna is
>> reflected back, it can heat up and even damage the circuit.
>>
>> ... I may be able to borrow a FLIR camera from a friend of mine - so
>> second question: if a spectrum analyzer is not available, what are your
>> thoughts on using a FLIR camera to avoid damage?
>>
>> Thanks!
>> Dave.
>>
>>
>>
>> --
>> George Bowden  250-893-7423
>> Victoria BC
>>
>> --
>> Projects mailing list
>> Projects at vicpimakers.ca
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>>
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>
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