Combined 24 & 47 & 76 GHz station

In Europe almost everybody uses 144 MHz as IF for microwave operations. This is mainly initiated by design's coming from Germany. To avoid difficulties in making a good narrow pasband filter for 24 GHz and higher I decided to use 1296 MHz as IF for 24 GHz. Some calculations showed that with the same LO used for 24 GHz it was possible to activate 47 GHz as well with the same IF of 1296 MHz.

24.192-1296=22896/2=11448 MHz
47.088-1296=45792/4=11448 MHz

But as happens before we had suddenly to move from 24192 MHz to 24048 MHz due to lack of international co-ordination and making a proper planning for microwave operation.

The results from calculations showed that with an IF of 1008 MHz the same trick was still possible. An other advantage of this change being the harmonic relation between the 24 & 47 GHz LO's. After some ideas and critical looks it showed that it was possible to generate all the required LO frequencies based on one single X-tall. Big advantage only one good oscillator is required and needs to be locked to Gallileo/GPS to have an accurate frequency on the required microwave band.

Here are the calculations:
96MHz *9 + 144MHz = 1008MHz
96MHz *120 = 11520 MHz

11520 *2 + 1008MHz = 24048 MHz
11520 *4 + 1008MHz = 47088 MHz

All the calculations can be seen in the block diagram below.

Due to lack of time I have not come further than some prototypes. However the 24 GHz transvertor has been tested with a positive result.

The same set-up can be made with 432 MHz IF. The block diagram below shows this.

Having some discussions with Eene (PA3CEG) we wonder if it was possible to expand the system with 76 GHz. This led to the idea where an additional 123 MHz signal was required. This was generated with a 27 MHz X-tall and some dividers and a "PLL". The result is in the block diagram below.

Having some "thoughts" about the "PLL" an other idea was born which is in the block diagram below.

In earlier days there has been a harmonic relationship between de microwave bands. Some of these relations still exists. So we wonder if more LO's for other bands can be exitited from the 96MHz. Once again Eene came with an idea.

96MHz /2= 48 MHz
96MHz + 48 MHz = 144 MHz(LO)

96MHz *96 = 9216 MHz +144 MHz(LO)= 9360 MHz
9360 MHz + 1008 MHZ = 10369 MHz

All the calculations can be seen in the block diagram below.

A disadvantage is the use of 144 MHz. This can give some trouble operating microwave in the near ficinity of a high power 144 MHz station. Mostly this occure during contests.

More about this subject will follow.

Back to PE1CQQ Page.
(c) PE1CQQ Last update 4-8-2007