.:: HERF004 ::.
This project is a continuation of the HERF003 project. It will be just like the HERF001 but many times more compact and efficient due to optimization and better calculated design. The actual device (excluding the horn antenna) will be about 50 times smaller in volume than HERF001 while having the same output power yet even better antenna efficiency and low VSWR. I hope to get much more detailed tests done on the effects and range of this device. Results and test images/videos will be posted allong with data sheets, radiation patterns and videos of test shots on dummy PC's.
- 800W 2.458GHz Magnetron
- 2kV @ 1.2uF capacitor
- 12kV piv microwave oven diode
- Sheet metal
- Sheet copper
- Other small parts
This is the basic magnetron coupling design. It is designed after the WR340 waveguide and can allow 1.70GHz to 2.60GHz to pass through with low attenuation. Of course my RF output will be within this range being 2.458GHz. The full dimentions of the waveguide are 4.318cm x 9.147cm x 8.636cm. The horn antenna is not as small as pictured. The magnetron feed will be inserted 1/4 the wavelength from the back of the waveguide.
a = 86.36mm
b = 43.18mm
c = 91.47mm
For a 15dB horn antenna:
p = 152.5mm
a1 = 320.6mm
b1 = 237.5mm
For a 18dB horn antenna:
p = 365.9mm
a1 = 452.9mm
b1 = 335.5mm
These are the dimentions of the plates that must be cut out in order to form a 15dB horn antenna.
These are the dimentions of the plates that must be cut out in order to form a 18dB horn antenna. Of course two of each plate must be made in order to make a complete horn antenna. The back end is then welded to the waveguide.
This is the circular waveguide and conical horn and its dimentions. The distance between the magnetron feed and the back waveguide wall should be fine tuned and adjusted as needed. The waveguide diameter is 3/4 the 2.458GHz wavelength and the distance from the magnetron feed and the base of the horn is 1/2 the wavelength.
This is the schematic of the HERF004 if powered from a 120VAC (or 240VAC) source. The circuit consists of a transformer and a voltage doubler cap/diode setup. A filiment heater is also needed.
This is the schematic of the HERF004 if powered from a 12VDC battery source. This design will provide less average RMS output power but will provide the same if not higher pulse peak power. Most magnetrons have the markings F, FA, C, or K next to the leads of which F, C and K are the magnetron cathode. Most microwave oven magnetrons will be marked with FA and F while radar magnetrons will only have one lead marked with either a K or a C. Since the magnetron I am planning to use is not a pulsed magnetron I will not construct a pulse forming network although it would help.
This clip shows a series of herf004 shots at different distances. The video clip contains both video and audio. In the audio you can hear the 60Hz hum as it was induced into the camera via 2.458GHz carier wave.
herflight01.webm (169 kB)
This clip shows HERF004 exciting the gas within a flourecent light tube causing it to glow.
herfmotion01.webm (223 kB)
This clip shows HERF004 triggering the driveway motion detector of my home and the house next door.
This is the horn right after its construction. I cut it out of sheet copper and then welded each sheet together. My welding skills weren't that great so the plates may be misaligned by upto 4mm. The horn was designed to be 17dB since my sheet copper wasn't large enough to make an 18dB horn. I will probably make a conical horn after this one though and use it instead since this one turned out to be quite large.
First HERF004 victim, me. As I was drilling a hole for the magnetron feed the drill bit caught the sheet of copper and swung it around slicing my hand in various places. I also got some burns from my blow torch.
Side of the 13dB conical horn with circular waveguide.
Front of the 13dB conical horn with circular waveguide.
Top of the 13dB conical horn with circular waveguide.
Side view of the mains powered HERF004.
Front view of the mains powered HERF004.
Back view of the mains powered HERF004.
© Copyright Rostislav Persion 2003