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Hazel1919

Mon Feb 20 2012, 11:18AM

Registered Member #1376 Joined: Wed Mar 05 2008, 08:31AM
Location:
Posts: 49

Hello,

I would like to start preforming some experiments in the Super High Frequency Spectrum using a microwave transmitter, but am unfamilier with the equipment and procedures at this frequency range.
Some help getting started would be appreciated.

In paticular I am interested in this piece of equipment, but could not find any information on the internet about it (Data Sheets/manuels).

Eyal Gal RF Transmitter Microwave ED-0295-0 7.1-7.9GHz

Perhaps someone here knows what this transmitter would have been used for.

In addition, does anyone here have information on the pulsing of microwaves?

Many thanks in advance.

Proud Mary

Mon Feb 20 2012, 12:37PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Point-to-point telecommunications, microwave relay links and such.

Steve Conner

Mon Feb 20 2012, 01:01PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I remember the Unilab microwave apparatus from my high school physics lab.

It consisted of two boxes with horn antennas sticking out of them. One box had a small low-powered klystron inside and the other had a detector diode and meter.

Who knows, maybe you can find something similar in a surplus store?

Sulaiman

Mon Feb 20 2012, 01:34PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

For a cheap (but very limited use) start try eBay item 320688389995
WiFi equipment may be a good start due to cost and availability.

Proud Mary

Mon Feb 20 2012, 02:29PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Here is an extract from the UK Table of Frequency Allocations for 7 - 8 GHz. Usage in other jurisdictions is likely to be very similar and shows the kinds of applications your device was intended for. As you can see, there is no allocation for licensed amateurs in this frequency segment.

A transceiver based around a scavenged 10 GHz Gunn diode module is probably the easiest way onto the microwave amateur bands.

Have a look at A simple wideband FM 10GHz transceiver with 30MHz I.F. by G3PHO

to get some ideas.

PS: If you haven't got a 30MHz receiver, you can easily construct a single-transistor super-regenerative detector tuned to 30 MHz as your IF amp and detector. It won't be as good as using a communications receiver, but will work fairly well in wide-band single frequency use on uncrowded bands, with sensitivities down to a few Î¼V possible with careful construction.

Hazel1919

Tue Feb 21 2012, 02:20PM

Registered Member #1376 Joined: Wed Mar 05 2008, 08:31AM
Location:
Posts: 49

Thank you very much for your responses, In particular the link Proud Mary gave.
Please excuse my extreme lack of knowledge on this subject but the issue I can see myself having with the 10 GHz gunn diode is that I require an output connection to test various coil configurations as antennae.
The Solfan Doppler Module has only a wave guide output.
I understand that working with high frequencys like this is very difficult because the wavelength is about 30mm and care needs to be put into the design.

This has given me a good starting point in any case.

Thank you very much.

Proud Mary

Tue Feb 21 2012, 03:31PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Hi Plasma,

You may also find The Radio Amateur's Microwave Communications Handbook helpful, which you can download free here:

This 1985 book is a bit short on circuit diagrams and construction at the basic component level, but still contains much that is worth knowing.

The 2.3GHz 13cm amateur band is a much more accessible place to get started, in terms of money, theory, workshop equipment, and constructional skill.

As for waveguides, don't forget that circular waveguides (copper pipe, tin cans!

) of diameter appropriate to the frequency work far better than any coaxial cable, though their propagation mode is a bit different to the more common rectangular waveguide type. Google tin can waveguide and/or coffee can waveguide to see how it's done.

Hazel1919

Wed Feb 22 2012, 12:58PM

Registered Member #1376 Joined: Wed Mar 05 2008, 08:31AM
Location:
Posts: 49

Thank you very much for your help and my weekend reading material!

Steve Conner

Wed Feb 22 2012, 01:18PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

The idea of a "coil" as a microwave antenna doesn't really make sense.

You can make a "Tesla coil" by attaching a 2.5cm length of wire to a metal disc and placing it in your microwave oven. With only 2.5cm of wire in the "secondary", what is the point of coiling it up?

Hazel1919

Wed Feb 22 2012, 02:26PM

Registered Member #1376 Joined: Wed Mar 05 2008, 08:31AM
Location:
Posts: 49

Hello Steve Conner.

As I mentioned before, I have very little knowledge in microwave frequencys therefore it is purely for experimental purposes. I am interested in what would happen if you connected a microwave signal of such physically short wavelength to an inductor of similar dimensions. Perhaps in a similar arraignment to the picture that is attached.

I have found a Microwave VCO here:

There appears to be three pins, VCC, Vt and RF. Further to this, I came across a web page

detailing the construction of a 2.3GHz transmitter. Would anyone know about amplification of signals at this frequency?
The Pulsing of Microwaves is also of interest.

I appreciate the time you take in your responses!

Many Thanks.

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