What is this?
Upper side
Bottom side
It has a coaxial cable. It says, SONY at the upper side and at the bottom side
at all. Inside of the case has a home made SHF antenna for a ETC unit to use
for pay roads in Japan.
3 years ago, a good friend of mine wanted to install an ETC unit to his car.
He went to different shops but he couldn't buy any. “All sold out” was what
he was told at every shop. He was in a hurry and he succeeded to buy a
unit at the Yahoo Auction. But that ETC was not with an antenna. He tried
to purchase the antenna from the manufacture but it was impossible.
He asked me,“Is there any way to use any other manufacturer's antenna
for this?”
I clearly said,“No”.
ETC antennas are designed and made to fit the particular ETC unit and it is
not OK to use an antenna designed for another ETC. He was a bit disappointed to hear my response. He was so desperate that I was in a mood to do
something for him. What I intended to do was to make a home made antenna
that has a same characteristics such as the gain, the beam pattern, V.SWR
and the phase. Luckily another friend of mine has the same ETC unit and I
asked him to allow to investigate only the antenna. Using a spectrum analyzer
and a horn antenna with home made adapters, I was able to get all the
characteristics and I could make a clone antenna installing into SONY's case
for an electlet condenser microphone.
He was a bit afraid of using it but I had a good confidence to use it as good
as the original antenna. Actually there never had any problem at the registration
office and the gates at the interchages every time the car passes through.
To tell you the truth, it has a bit higher gain and a sharp beam pattern with lower
V.SWR. These make it possible to work a bit better and quicker. I want to show
you the inside how the elements are organized but it is related to my patents
and I am sorry I can not show it.
