Microwave Stimulation Bob Horst
As Mats said, the antenna is the key. If the antenna does not resonate at the transmitted frequency, the
SWR will be very high and most of the energy reflected back. Not only does that greatly reduce the
RF energy entering the core, but the reflected power could burn out the amplifier.
It is possible to use a simple quarter-wavelength antenna, but then we are stuck with a single
frequency. Given that we may not know the best frequency in advance, it would be better to design
for a range of frequencies. The attached files show a set of equipment that can cover 700-2400 MHz.
The Analog Devices synthesizer chip is available on a demo board and can be purchased in combination with a touch-panel
controller for $66. See
I have one on order that I will try at home first. If this is not good, we could borrow a sweep
generator if someone has one that covers this frequency range.
The amplifier is one of many available from
There are more with higher and lower power than the attached datasheet for the 125W amp. The
owner of the company is a friend of a friend and I can later contact him to check prices or if a loaner
could be arranged.
The antenna is low cost (< $100 from Ebay) and covers a broad frequency range with low SWR. We
can remove the plastic Radome and then the aluminum elements should be able to stand the high
temperatures. This antenna is directional with an impressive gain of over 8 DB. We may be able to
aim it at the core and get away without full RF shielding of the experiment. Instead, we may be able to
position and shield the other equipment to keep interference low enough.
Icon_pdf_big ADF4350 437-4400 MHz synthesizer.pdf
Icon_pdf_big RF Amp 700-4200 MHz 125W 125S1G4.pdf
Icon_pdf_big Wilson 700-2700 MHz Log Periodic Antenna.pdf