[OZAPRS] VK2HAB 25/05/16

Matthew Cook vk5zm at bistre.net
Thu May 26 16:40:22 AEST 2016


Norm,

In truth just a short mobile whip, one of those short diamond CR-77's
usually.

http://www.strictlyham.com.au/diamond-cr-77

They have such a horrible pattern and gain they work quite well in this
application (*grin*).

The best and cheapest antenna I've found yet for HAB work is a pair of
crossed dipoles over a ground plane.  I've so far built one for the car on
70cm and one for home on 2m.  The crossed dipole at home just sits on top
of the verandah.

If you look carefully at this image in the centre of the car roof you'll
see my crossed dipole over a ground plane on 70cm.  On the driver side
front quarter panel is the CR-77 for 2m.

http://projecthorus.org/wp-content/uploads/2011/12/STA_1943.jpg

The crossed dipoles were made with a magbase, PL259 connector, 25mm pvc
pipe, hexagonal tin plated standoffs, 75ohm coax & welding rod.  Cost me
peanuts, is deadly on 70cm. My 2m one I built using broom handle, welding
rods and some RG59 coax.  I can copy the ISS and HAB's with a preamp from
horizon to horizon.

Other alternatives are Turnstyles, egg beaters, QFHA or J-poles.  Any of
the LEO satellite antennas are good for HAB work on 2m.

YMMV

73

Matthew
VK5ZM

PS:  That's me with the beard in the photo above.

On 26 May 2016 at 15:17, Norm McMillan <vk3xci at gmail.com> wrote:

> As a matter of interest... what do you use for a 2M antenna? Given that a
> 1/4 wave vert has a doughnut hole right underneath, assuming it's hanging
> from the payload, and a dipole or turnstile would give polarization issues?
> Then there is weight to consider.
>
> norm
> vk3xci
>
> On Thu, May 26, 2016 at 2:50 PM, Andrew Rich <vk4tec at tech-software.net>
> wrote:
>
>> You shoul copy aircraft systems
>>
>> -----------------------------
>> Sent from my iPhone
>> Andrew Rich
>> vk4tec at tech-software.net
>> www.tech-software.net
>> 0419 738 223
>>
>> > On 26 May 2016, at 11:08, Matthew Cook <vk5zm at bistre.net> wrote:
>> >
>> > Hi Norm,
>> >
>> > That sounds about right with respect
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