[mythtv-users] Attic Antenna: simple question.

[blind Pete]

On Sat, 06 Sep 2014 13:18:44 -0400
Bert Haskins <bhaskins at chartermi.net> wrote:

> 
> I have been trying to recover at least a few channels after charter
> effectively  bricked my HDHR. One, CH8 is marginal and in an attempt
> to improve it I want to modify a existing antenna. The antenna has
> all of the elements including the center point of the dipole
> connected (grounded) to the main beam which then is bolted to the
> grounded mast. This just doesn't seem right to me, i.e. it seems like
> the dipole should be insulated from all the other parts(?). I've
> searched the net and found lots of other information but nothing on
> this.

Antenna design is a bit of a black art.  

With a Yagi-Uda design all of the directors and the reflector are 
simple conductors insulated from the boom.  There might be a bunch 
of plastic washers and sleeves where they are not obvious to the 
casual glance.  

If you doubled the length of the passive elements there 
would be a node at the centre, so electrical connection 
would be OK.  But that would make the antenna twice as 
large as necessary.  Such a design would surprise me.  

With a log-periodic antenna there are two parallel booms.  half 
of the elements are electrically connected to one and the other 
half are connected to the other.  

Many, many, weird and wonderful designs are possible.  

If you like mucking about with this stuff, go for it.  

If you just want a marginal signal to be a bit better 
consider buying a new (corrosion free), slightly larger antenna.  
Make sure that it is pointing in the right direction.  
Check that there are no obstructions, hills, neighbour's 
new attic, wet trees, etc.   Yes, at some frequencies a mess 
of leaf sized conductors will block a signal.  Dry leaves 
don't conduct enough to matter.  Then all of the usual stuff, 
check the cables and connectors.  Is anything generating 
electronic noise nearby?  

> BTW it may be of interest to note that the (1 year) cable box has
> been downgraded bigtime from previous units.
> No firewire, no channel display, and overall sort flaky operation.
> I am not planning to "cut the cord" yet but I'm not happy either.
> 
> Thanks,
>    Bert



-- 
testing
bP