On 3/16/2014 9:43 AM, Ian Jackson wrote:
In message , Channel Jumper
writes

The only people that worries about SWR is CB'rs.........

CB'rs only has one half of one megahertz to play with - hence antenna
tune is critical.

If all you are going to play with is one frequency or one band - then I
guess you are going in the right direction.

The missing information that my crystal ball is not clear on is the make
and model of the vehicle and antenna.

With HF it is more important to have a large metal ground plane - large
Suburban sized vehicle, that has all of its surfaces physically bonded
together with a wide copper braid straps at all hinge points and corners
- such as a pick up truck front walk away, hood, doors, cab, bed,
exhaust, engine, transmission, exhaust, suspension etc..

It's more important to bond these surfaces together then it is to tune
the antenna so it looks good on the analyzer.

At the same time, the ground conductivity changes as the vehicle moves
down the road, so unless you plan to never move the vehicle again and
operate from that one spot - the tune of the antenna will change with
the earth as you travel down the road.

Hence it is not as critical to get a perfect match in a vehicle as it is
using a home install that is not going to move once it is installed.

Can you see my point?

If you have a small plastic car - forget about trying to get a perfect
match.

I've never been aware of the antenna tuning changing as you drive along
over ground where the conductivity changes. However, especially on the
lower HF bands, being over an area of high ground conductivity certainly
enhances RF signal level (both TX and RF).

It doesn't (not who was posting the crap). Any change in ground
conductivity is so minor compared to everything else it will have no
discernible effect on the antenna tuning.

The antenna moving back and forth in the wind will have a much greater
effect.

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Jerry, AI0K

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