[Antennas] On The Glass Antennas

[Chris Boone]

A coupling plate on an on-glass antenna is a percentage of the
wavelength...on Larsen antennas where the coupling is done at LOW Z
(High Z is a waste of RF through the glass), the lowest freq they make
such is 2mtrs..I inquired about a lowband VHF model for use on
48MHz...Larsen laughed saying it would as big as a windshield is tall!
(which is about right)..
On HF, you would have to have the thing maybe 15ft or more big on HF.
Forget the onglass idea for HF....it is not the way to go..

Use a dryer vent pipe and hood...run the cable through after drilling
and mounting the pipe/hood thru the wall, and then use expanding foam
with no acid in it to fill the pipe up after running the coaxes thru it
to the outside..
IF you want to go an expensive but versatile way, mount a thick plate of
AL under the roof eave....with several different coax bulkhead
connections on it....either female to female or female to coax bulkheads
will do..run the coaxes inside the roof to the shack...use another plate
at that end and this way you have several runs of coax (different
styles, say
1 or 2 7/8in, a couple of 1/2in and 3-4 LMR400 or RG8 style and maybe
two-3 RG58s and RG59s or RG6 for 75 ohm use)
And you can mix/match as needed..

Chris
WB5ITT

> -----Original Message-----
> From: antennas-bounces at mailman.qth.net 
> [mailto:antennas-bounces at mailman.qth.net] On Behalf Of 
> fkamp at comcast.net
> Sent: Saturday, September 04, 2004 7:28 PM
> To: Hue Miller
> Cc: antennas at mailman.qth.net
> Subject: Re: [Antennas] On The Glass Antennas
> 
> 
> 
> 
> Hue Miller wrote:
> > 
> > The reason i became interested in thru-glass, is yes, for 
> home use to 
> > get RF thru glass, as for a balcony, without having to 
> pinch cable in 
> > a door. I have a couple replies that were interesting enuff, i hope 
> > the senders posted to the list also. I was a wee bit leery about 
> > large-ish aluminum foil pads on window glass just because high-Z 
> > points out in the open could be entry points for  local 
> noise. That's 
> > why i'm interested in how a low-Z, thru-glass system works. As in, 
> > imagine a receiving HF loop on the balcony, how to bring the coax 
> > inside without holes, cable pinched in doors, or noise from exposed 
> > wiring.
> 
> 
> I don't ever recall seeing through the glass antenna coupling 
> without holes on HF stuff.  Most of the schemes I have seen 
> are designed for VHF.
> 
> I can understand why such a scheme would be attractive as 
> long as it works, and works up to several hundred watts on transmit.
> 
> In my case I use a section of white painted lexan that mates 
> with the bottom on my window sash.  Ceramic feed through 
> insulators take care of the open wire line and holes are 
> drilled for coax.  Everything is weather proofed with caulk 
> and the window has been modified to lock even with the added 
> section of lucite.
> 
> One approach that I have seen in some of the older literature 
> is to remove a pane of glass from multiple pane window.  
> Replace it with a sheet of lexan that is drilled for your 
> feedthroughs for antenna leads. 
> In retrospect that appears to be the more suitable method.  
> You can always restore the window to normal by reinstalling 
> the original glass pane.
> 
> Regards,
> Frank Kamp
> - - - 
> 
> Your moderator for this list is:
> Larry Wilson KE1HZ antennas-owner at mailman.qth.net 
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