Go Back   WorldwideDX Amateur Radio Forums > Citizens Band Related > CB Antennas


Amateur Callsign Lookup
Enter Callsign:

THROUGH THE GLASS ANTENNAS

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-01-2010, 10:27 AM
TonyV225's Avatar
W9WDX Amateur Radio Club Member
iTrader: (8)
 
Join Date: Apr 2005
Location: Wisconsin
Posts: 5,626
TonyV225 is on a distinguished road
Default THROUGH THE GLASS ANTENNAS


How do these things work?? Is it a mist for the outside whip or antenna seeings how theres actually no connection between the 2 antenna parts?I actually bought a box of odds and ends and there was a brandnew through the glass but the stinger or outside mini whip is missing

I thought about using this when doing a trip if someone doesnt have a radio or antenna I can put a portable setup together for them with this antenna and if need be will have to mak a new outside stinger. I already know they are not the best way to go but for a portable for someone with nothing it will be fine for a few hundred feet of communicating or monitoring / emergency.
__________________
""""was not thinking of a cber sat with his makita screwdriver winding round the presets untill his meter said s9+60db from a guy on a handheld 15 miles away""""


Reply With Quote
  #2  
Old 11-01-2010, 02:12 PM
hookedon6's Avatar
W9WDX Amateur Radio Club Member
iTrader: (0)
 
Join Date: Jun 2008
Posts: 1,492
hookedon6 is on a distinguished road
Default

i'm not sure of your question.

are you asking how (why) they work?
or
are you asking how (well) they work?

@VHF & above, i have run 100 wats thru one with no problems.

as far as "why" they work, think of the 2 sides as the primary and the secondary of a transformer

Reply With Quote
  #3  
Old 11-01-2010, 02:23 PM
Senior Member
iTrader: (0)
 
Join Date: Oct 2010
Location: Macclenny,Fla.
Posts: 115
SIX-SHOOTER is on a distinguished road
Question Thru glass!

Most that I have seen have ONLY 50 watt or so power ratings so that could be an issue with some of todays rigs with higher output on 2 meters & 440 mhz.I have NEVER heard ANYONE bragging about how GREAT their THRU THE GLASS antenna was either! The connection is ALL RF thru the glass so that may be the issue with output power?

SIX-SHOOTER
__________________
ICOM 756 PRO II,ICOM 746 PRO,ICOM PW-1,REALISTIC TRC-458 & TRC-490 NAVAHO's,PRESIDENT MADISON

Reply With Quote
  #4  
Old 11-01-2010, 03:15 PM
Crotchety Old Bastard
iTrader: (0)
 
Join Date: Apr 2005
Location: Oklahoma
Posts: 6,799
W5LZ is on a distinguished road
Default

Those 'thru-glass' antennas work because the two parts act like the two plates of a capacitor. RF is AC and AC can 'pass' through a capacitor rather easily. The 'size' of those two plates, along with what separates them, determine the value of the capacitor.
Never having 'played' with them to determine the required size of those plates, or the dielectic insulation between those plate, I won't even guess as it. I can tell you that the frequency is also important in all that because 'higher' frequencies require 'less' capacitance than 'lower' frequencies.
Power ratings for the things? I don't know, but I certainly wouldn't expect as much capability as with a "real-live" antenna. That automotive glass insulated capacitor just isn't going to have a huge power rating.
Do I like the 'thru-glass' antennas? No, and I wouldn't have one unless absolutely necessary. Do they work? Yes, they do. Very well? No. They are adequate at VHF/UHF and higher, but forget it for HF. Just want one, or have to have one for some reason? Fine, do it. You can have the one reserved for me, tell'em I said so.
- 'Doc

Reply With Quote
  #5  
Old 11-01-2010, 04:05 PM
packrat's Avatar
Senior Member
iTrader: (7)
 
Join Date: Sep 2008
Location: S.W. Florida
Posts: 757
packrat is on a distinguished road
Default

Wouldn't be any good for "portable" use, as they are glued in place, and kinda difficult to move around. Also, I hear they are pretty picky when it comes to exact alignment of the plates.
__________________
Incentives are important.....I learned that in rehab!

Reply With Quote
  #6  
Old 11-01-2010, 05:08 PM
TonyV225's Avatar
W9WDX Amateur Radio Club Member
iTrader: (8)
 
Join Date: Apr 2005
Location: Wisconsin
Posts: 5,626
TonyV225 is on a distinguished road
Default

I was actually thinking about making a scanner antenna out the one I have. I was thinking about that today and found replacement outside whips and plates with the adhesive but I am wondering if this would work at all. I have the main part but never got the outside plate and antenna so I found these replacements but there for cell phone I believe.
__________________
""""was not thinking of a cber sat with his makita screwdriver winding round the presets untill his meter said s9+60db from a guy on a handheld 15 miles away""""

Reply With Quote
  #7  
Old 11-01-2010, 05:56 PM
Captain Kilowatt's Avatar
Professional Amateur
iTrader: (1)
 
Join Date: Apr 2005
Location: Nova Scotia,Canada
Posts: 10,536
Captain Kilowatt is on a distinguished road
Default

Doc is correct about the basic principle of operation being like a capacitor. I have used one on 2m and it was not bad. I actually made one several years ago when one of the radio station's clients wanted to play our audio thru their PA system but could not pick us up inside the mall,too much concrete and steel. It was also nearly impossible to run coax cable thru the brick wall but a sealed window was nearby.Myself and the other engineer at the time made up two pieces of copper clad PC board with the center of the coax cable connected to each plate, one inside the window the other outside, and the shields connected to the window frame on each side. The inside piece went to the receiver and the outside piece went to an FM antenna mounted on the roof. It worked like a charm with no continuity between the two pieces.
__________________
Marriage is like a deck of cards. In the beginning all you need is two hearts and a diamond. By the end you wish you had a club and a spade.

Reply With Quote
  #8  
Old 11-02-2010, 11:22 AM
Crotchety Old Bastard
iTrader: (0)
 
Join Date: Apr 2005
Location: Oklahoma
Posts: 6,799
W5LZ is on a distinguished road
Default


I've also seen pictures of such a 'thru-glass' system, home made, for use on the HF bands, which did work adequately. It definitely was not small, was not simple, and while the cost wasn't discussed, I'll bet it wasn't cheap either! Was too large for a mobile unless you drove something with windows the size on a Grey Hound bus. So impossible, nope. Unlikely, very much so!
- 'Doc

Reply With Quote
Reply

Bookmarks
Worldwide Radio Forum



Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Glass mount scanner antennas... KC9NTO Scanning & Shortwave Listening 11 06-05-2011 05:57 PM
Difference between 2m and 70cm HT antennas? ke7vvt Amateur Radio Antennas 2 01-17-2010 04:33 PM
baluns towernewbie Amateur Radio Antennas 16 03-02-2008 04:11 AM
Safety Standard for CB Base Antennas Master Chief CB Antennas 0 09-04-2007 09:09 AM
Antennas and the lies we tell... hossless CB Antennas 1 02-25-2005 09:21 PM


All times are GMT -7. The time now is 06:07 AM.


Powered by vBulletin®
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0
Worldwide Radio Forum