Marine Radio using Aviation Antennae

Horsefeathers. A 2:1 VSWR transmits 90% of the applied power. A 3:1 VSWR
transmits 75% of the applied power. Have you actually ever MEASURED a
commercial aircraft band antenna from bandedge to bandedge as installed on an
aircraft?

Jim


(Steve Roberts)
shared these priceless pearls of wisdom:

-find a ham radio operator in your area with a VHF capable SWR meter
-(or just order a 2 meter swr meter from AES) if the SWR (standing
-wave ratio) is greater then 2:1 then the antenna is not well enough
-matched for even casual use.
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

As I'm sure you know, and to be fair to the previous poster, you are
implying 90% of full power for 2:1 VSWR. As he stated any decent
transmitter has VSWR protection so it will back off the power to
protect itself. You will then only transmitt 90% of what the
transmitter is now putting out!

Do you know what transmitter output power would you realistically
expect in these conditions?

Personally I have accept 3:1 VSWR for occasional use as long as the PA
is protected. One time on holiday I lost one half of my 14MHz inverted
V dipole but still manage to reach UK from Southern Spain with 10W
SSB. Don't even ask what the VSWR meter was reading, it looked like it
was all being reflected!

On Mon, 11 Aug 2003 07:45:34 -0700, Jim Weir wrote:

Horsefeathers. A 2:1 VSWR transmits 90% of the applied power. A 3:1 VSWR
transmits 75% of the applied power. Have you actually ever MEASURED a
commercial aircraft band antenna from bandedge to bandedge as installed on an
aircraft?

Jim


(Steve Roberts)
shared these priceless pearls of wisdom:

-find a ham radio operator in your area with a VHF capable SWR meter
-(or just order a 2 meter swr meter from AES) if the SWR (standing
-wave ratio) is greater then 2:1 then the antenna is not well enough
-matched for even casual use.
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com



E-mail (Remove Space after pilot): pilot

Ken Mattsson wrote:
if your just gonna receive, the airband antenna will be just fine.

Steve Roberts , N8VKD


Steve,

I was just thinking of using it with the scanner, no transmitting, on the
ground and not from the air.

But back to the basic question. Can this J-stick design by Jim be used for
any bands, that is be built for any specific wavelength, or is the J-stick
design for some reason good only for the VHF-range? You see, it would be fun
to build a couple of these antennas on other wavelengths just to explore
what can be heard. A set of base antennas for snooping around on the
different bands. Now that I have found out where to get parts for this water
pipe antenna, it would be relatively easy to make a few more, if only the
desing allows for it.

Best regards, Ken


Yes, it will. Just use the formula to make the elements the
proper lengths for your frequencies of interest. The J is a classic
and will work for most any band. You may need to use guy wires
if you descend into the HF bands, however. 8-)

Tom Pappano, PP-ASEL-IA

Not to mention the filing with the FAA for airspace intrusion {;-)

Jim


Thomas Pappano
shared these priceless pearls of wisdom:

You may need to use guy wires
-if you descend into the HF bands, however. 8-)
-
-Tom Pappano, PP-ASEL-IA

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com