indoor7.art

一个很小和天线计算程序

SUBJECT:  Tape Antennas - part II
          o    Tape antennas on sun-film windows
          o    Tape antennas on screened windows


Tape antennas on sun-film windows:

       Using the tape loop, discussed earlier, I tested the antenna 
on two types of sun-film windows.  The first was a plastic film, often 
used in states such as Florida.  There was no significant pattern or 
gain change for the antenna.  The second type of film is the metal film
sun screen.  

       Results here were dramatic.  The pattern was severely disrupted as
well as SWR.  Be sure that your window films are not the metalic type if 
you plan to use indoor VHF/UHF antennas pointed out the window.  The metalic
film acts like a reflector to the signal.  Attenuation is a strong
factor concerning propagation.  Some plastic films appear metalic, but may 
not be.  


Tape antennas on screened windows:

       There are a three types of screen used as screening for windows. 
Plastic, fiber, and metal.  The first two show some attenuation of the
gain and pattern shape is similarly effected.  Basically, the addition 
of the screen frame effect the VHF spectrum greater than the UHF spectrum.
The screen frame size is near the size of VHF loops at frequency.

       Metal screen acts similar to metalic film with greater effect. Using
the top portion of the window is the best bet unless you don't have windows
like the type used in the Northern States.


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       Here in Florida, I have single windows that slide to the side rather
than the older storm type in Connecticut.  The film on the windows is 
plastic.  Testing was conducted here at my QTH and at the Electromagnetic
Laboratory, KSC, FL.  Questions can be directed to me here on this echo.
(HAM or HAM_TECH)


-WS