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Maybe the matching at 70cm band is better because the coaxial cable losses are higher there ?

If I remember right there was a considerable length of lossy RG58 used during the measurements ?

Kind regards

Matthias

www.dd1us.de


-----Ursprüngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von W0LEV via groups.io
Gesendet: Donnerstag, 3. August 2023 19:38
An: [email protected]
Betreff: Re: [nanovna-users] Double Discone VSWR

I checked this antenna on the Moonraker site, specifically amateur radio antennas. It's rated for ONLY the 70-CM BAND.
[image: image.png]
Sure, it will receive over a wide band with relatively poor efficiency, but for transmit - low SWR - it's rated for only 130 to 175 MHz and 410 to 475 MHz. This is pretty much what the SWR sweeps have shown with the exception of the 2-meter and aircraft bands. The SWR sweeps that have been shown in this thread exhibit low SWR ONLY in the 70-CM BAND. That's what the spec's show!

Further, the claimed 5.5 dBi over a standard discone is bogus. A standard discone radiates (and receives) pretty much like a 1/4-wavelength over an image plane. 5.5 dBi over this is not realizable. And I can imagine, if it were, that figure would apply only to 70-cm.

Dave - W?LEV




On Thu, Aug 3, 2023 at 4:19?AM Bob Ecclestone VK2ZRE <becclest@...>
wrote:

I am surprised some folk on this group have rubbished Moonraker Antennas.
I know Moonraker HF antennas are used on some Australian Navy ships,
so I don't think they are really "Dollar Shop junk."
I don't have any connection with either Moonraker or the the
Australian Navy.
So perhaps those with complaints may need to examine their
installation practices.
Or contact Moonraker or their dealer for support.
Just my 2c worth.

Cheers...Bob VK2ZRE


On 3/08/2023 2:33 am, Clyde Spencer wrote:

one has to consider the environment, not discussed prior in this thread.

If

there were any metal or other electrically conductive material near
the antenna when tested that could be a possible cause for the
difference in measurement data and that which is published.
*Clyde K. Spencer*



On Wed, Aug 2, 2023 at 11:09?AM Jim via groups.io <teotwaki=
[email protected]> wrote:

This antenna is related to what antenna design literature calls a
“产颈肠辞苍颈肠补濒“

- - Biconical antennas have dipole characteristics. The double cone
elements structure contributes to their wider bandwidth. The
antenna becomes more broadband as the cone angle increases. - -

Search on that name for design and results discussions

Jim

--

*Dave - W?LEV*


--
Dave - W?LEV