Of all the terms and jargon in ham radio, "Standing Wave Ratio" has to
be at least in the top 5 misunderstood ones, and maybe even top 3. It
didn't even really enter the ham vocabulary until the middle of the last
century.
Helping a ham trying to use an 11 m vertical-ish wire on 80 m, was
instructive. Rig was a KX3 with ATU. ATU indicated about 1.3:1 SWR,
but no contacts. EZNEC4 and TLW revealed the "gozinto" end of the coax
looked like about 0.4+j<big> ohms
The totally misnamed "Antenna Tuner" matched that to what the radio
thought was roughly 50 + j0 ohms [L-networks are good at that].
However, that network, plus I-squared R loss in the connectors, cable,
and wire were eating almost all the power. Ultimately, center loading
the wire raised the RR to about 20 ohms, lowered the reactance, and the
ATU still reported about 1.3:1 SWR. Only now, there were contacts now
being made.
My KAT2 will match a 1 foot RG-58 jumper on 15 meters to about 1.5:1
however I won't make many, if any, Q's.
73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
/31/2017 3:09 PM, Bill Frantz wrote:
However, these radios do report a SWR in the UI, and that is what I
was referring to. Since a naive user might look at that figure and
say, "The SWR is 2. The antenna must be good.", it is important to
know that the tuners can produce a low figure on that meter with
nothing connected to the antenna connector.
73 Bill AE6JV
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