omni-directional waveguide horn

Hi everyone
I want to design an omni-directional antenna with frequency of 11.4-11.6 GHz. Antenna must be waveguide horn. Now my antenna has very narrow directivity pattern. How can I made wider pattern without changes of the radius of waveguide?
Thanks

you need a hihat brass symbol set

and turn upside down

and tune add some sliding units as needed
and braise them up using brass tubes ...{not the best but you can plate them and smooth them as symbols are riged

or approch a symbol maker and ask for machines parts untuned as the tuning process add's the ridges

make a template using this system then get something machined from a solid block

only thing i can think of for omni

or maybe two wok's for simple experiment's

maybe you can add sliding trumbone style but on gaps and as for sizes of guide

then im not sure this is possible on omni without some sort of moving guide media
like above..:?

and maybe two flat circles on silvered polyfilm
if the power isnt too high output or is for rx only

look to mucial brass etc .. instruments
and change there plane .. from vertical to horizontal

thanks a lot. and if i want to reduce the influence of another antennas can i use chokes?

i have no idea what the guy above it talking about. however, we need to know a bit more about your gain requirements. sounds as if you need a slotted waveguide. there are techniques you can use to make the pattern reasonably omni, but tends to work better if your required directivity is a few db.

gain requirement in max is about 4-6 db, and the pattern must be as wide as it imposible. Desigh of antenna is open-end of waveguide. Also i want to use chokes. Could you tell me about that techniques?

you really need to define your definitions, or at least understand the ones you have given :)

a waveguide opening or a horn antenna/radiator is, by definition, directive. They are NOT omni-directional. A slotted waveguide radiator (as suggested ny one other poster) has an excellent omni-directional radiation pattern which is made even better by the use of "wings/fins".

do some goodle searching on slotted antennas or read up some of the ARRL antenna handbooks

Dave

do not use a horn antenna is the answer
use a radiator mounted in free space

between two symbols {drum symbols}

if you want gain
mount re-radiators some distance from the funnel guide antenna

its the same way as phase radar works
its just a small set of symbols mounted one above the other


rx tx tx rx

if you dont understand shapes
then you dont understand microwaves...

for omni direction you must not use a horn

uni direction of a spread will work with a horn

omi only works with an rf funnel and exibits gain in an onmi and planar proportion

4-5 db is a small dipole gain

you need 7/8 wave stacks as re radiators
and some shape to the discone wave radiator you use

you also need a small inflector like a mushroom below the top symbol

top reflector {> }<---- in bottom

tune 90 deg clockwise the above
the > is the inflector
the { a symbol shape reflector with bevel inflection

/|\ bottom
/^\ top

---------- Post added at 07:24 ---------- Previous post was at 07:17 ----------

so you can use chokes
but only on the feeder and build a balance breaker
if you wish to mount with other antenna
its best to leave it all planer insulated

...

---------- Post added at 07:26 ---------- Previous post was at 07:24 ----------

omni and horn dont belong in the same sentance ... they are a contradiction ,... in fact..

---------- Post added at 07:33 ---------- Previous post was at 07:26 ----------

you can make such antenna like the army does made of rubber that has a high carbon

on there jeep the antenna main element is hf and vhf and uhf

the bottom suspension of it is shf and sshf for phones etc

it uses upside down mushroom cap shape
one above the other

its hard to discribe

but each pair of plates is a sub size of the one above

it just looks like a spring for the antenna
but really its the key to the whole radio they use ... ...

upside down discone

but for real use with more than 2-2.5 db gain
you must use re radiators and fixed metals tuned to an exact size

this avoids any cross talk ...between stacks

---------- Post added at 07:38 ---------- Previous post was at 07:33 ----------

i think your total post is therefore a contradiction

why narrow a beam from an omni direction antenna

there is no such element unless you work duplex...

if you do
use a fractle antenna... for tx and omni discone for rx

not even a dipole is omni unless you use re-radiators ...

a horn isnt a discone is
why use a discone for direction ....?
you get 7.5db from a yagi over 5 elements in a loop 1.5 foward to back

an omni will give 2db max without directors and rediators,,,

A complete construction guide is given here:
Universitt Duisburg-Essen - Hochfrequenztechnik - Amateurfunk
the reference is available in german only: http://hft.uni-duisburg-essen.de/amateurfunk/hlssa.pdf

i concur with dave, open ended waveguide contradicts your request for omni pattern. just for giggles, you could make a slotted waveguide array with the omni pattern and gain you have noted, while leaving the ends of the waveguide open. so technically it would be an open ended waveguide antenna (with some handy slots )