Simple 60 GHz Oscillator?

Thread Starter

eromlignod

Joined Dec 8, 2012
4
Gentlemen:

I have a new application (proprietary, so I can't tell you a whole lot about the device) where I need to provide a simple RF continuous beacon. I need to be able to detect the signal from a few hundred yards away. There is no modulation or encoding of data, just bursts of 60 GHz carrier wave. I need millimeter waves because the application is so tiny that I have no room for an antenna for longer-wave bands. There will be no line-of-sight for anything optical and the product is embedded where ultrasonic is of no use. It's also a consumer product where low cost is important, so full-blown RF transmitter chips are out of my cost range.

Is there anywhere to buy or construct (SMT chip size) just a super high frequency oscillator like this for less than $10?

Don
 

bertus

Joined Apr 5, 2008
20,227
Hello,

On 60Ghz you will have major problems with obstackes in the way of the signal.
From the wiki:
Compared to lower bands, radio waves in this band have high atmospheric attenuation: they are absorbed by the gases in the atmosphere. Therefore, they have a short range and can only be used for terrestrial communication over about a kilometer. Absorption by humidity in the atmosphere is significant except in desert environments, and attenuation by rain (rain fade) is a serious problem even over short distances. However the short propagation range allows smaller frequency reuse distances than lower frequencies. The short wavelength allows modest size antennas to have a small beam width, further increasing frequency reuse potential.

https://en.wikipedia.org/wiki/Extremely_high_frequency
Here are some product pages:
http://www.insight-product.com/60_GHZ.htmlhttps://www.balticnetworks.com/mikrotik-wireless-wire-60ghz-ptp-gigabit-link-kit.htmlhttp://www.60ghzwireless.com/
As said, you will need a clear path to have any signal left at the mentioned distance.

Bertus
 

Papabravo

Joined Feb 24, 2006
12,767
There is no such thing as a simple 60 GHz. oscillator. You should also consider purchasing at least a 10X rifle scope to aim transmitting antenna at the receiver dish.
 

Thread Starter

eromlignod

Joined Dec 8, 2012
4
Thanks guys. Yeah, I may be pushing my range a little with 60 GHz. I found some little Gunn diodes on eBay that are 30 GHz, which would only require about a centimeter antenna. I might be able to make that work. I was shooting for 60 GHz so that I could get in on the unlicensed millimeter ISM band.

I wish I could find a source for the Gunn diodes other than ex-Soviet military though.

Don
 

bertus

Joined Apr 5, 2008
20,227
Hello,

As said before, for 60Ghz you will need a line of sight.
Anything in between the line of sight will block the signal.
A long time ago, I did some experiments on 10Ghz.
A hand between the transmitter and receiver was enough to block the signal.

Bertus
 

danadak

Joined Mar 10, 2018
3,782
Never worked up there, 60 Ghz. I am thinking just creating a short
a real challenge, let alone confirm and observe 60 Ghz oscillator
functionality.

Where mathematics and art compete for reality.

Regards, Dana.

PS : Did a H line 21 cm parametric amp in HS for a radio telescope. First time
built it like it was an audio amp. Microwave engineer renting a garage told me
thats a serious wasted of solder. Read a book, rebuilt per governing practice at
time. Lost the regional science fair award because I was told it was built
by a professional, could not have been done by a teenager. Lesson learned,
be careful when judging others. Especially their work.
 

Janis59

Joined Aug 21, 2017
965
How far I can see, to avoid use of magnetron or klistron, You may try to build a common-base oscillator circ on basis of 7 transistors for choice - f(betah in brackets)
1) BFU910FX (90 GHz)
2) BFP840 FESDH and ESDH (85 and 80 GHz)
3) BFR840L3 (75 GHz)
4) BFP620H (65 HGHz)
5) BFP842ESDH and ADR5740 (60 GHz)
Here are bits of circuitry guidlines https://www.mikrocontroller.net/attachment/82537/High_Frequency_VCO_Design_and_Schematics__VA3IUL.pdf

If my task, I would beforehand tried to warm up the hands with sth like modified Clapp circuit with (1) transistor. Modified means throw out C3 and C4 from circuit of page 4. There the inner parasythics works well enough instead. L2 and R2 must to be, tank is obligatorium, R1 and R5 MUST !!!! be insulated for RF by means of choke. Otherhow them always burns off in seconds. C1L1 and all more left of them throw away. Instead of place where stays in circuit R1 place the serial contour of tanks. May use the coaxial structure with known uniform L and C, as the lambda is 300/60 000=~5 mm means no any other dielectric except the air. Dont near the any pcb except the teflon-based, best to "hang up mount". Then, if no satisfactory result obtained (but this circuit generates a kilovolts thus may be essential for any power-works), may try to make a common base capacitative bridge - base is biased by two resistors as normally but for RF earhed by cap. Emitter is sinked via not big resistor, for taking off the signal. Collector have tank contour. The E to C stays positive feedback loop. If not help even this circ, try up the cascode schematics (see article i the link). In attachment is short circuitry history, and You should concentrate on the fig 5 (Modified Clapp).
 

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Janis59

Joined Aug 21, 2017
965
Ah ya, there is more one extra vivid circ well working on 2 GHz, thus I cannot see why it not work well even on 60 GHz. Take a transistor of rather high power (originally 5W mosfet, but I cannot see any reason it may not pass a bjt as well). So, make Gate (or Base) via RF choke to the biasing potentiometer. Adjust good bias for Your aim according the datasheet. Between Gate and Drain (B to Collector) apply the feeder line resonator described below. Just few mm thick wires or plate-cut-outs, one soldered to B and onother to C, having near distance parallel one to other). For case of 2 GHz the gap must be about 1...4 mm and length about 10...15 cm, thus let make it proportionally smaller. When work will go on, the heavy Microvawe arc will happen between both resonators, kind of fireball sliding up and down searching the smallest gap distance. Collector/Drain set to the gnd via 4-7 pF trimmer (thus apply proportionally smaller at 60 GHz), and organize the DC power feed to the drain via certain choke (some 6 turns at 2 GHz thus smaller coils at 60 Hz). Plasma means that voltage and power is really impressible, just laid it to antenna. More over, actually both resonators form the antenna. Maybe is worth to bend wider the ends?
 

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