[VHFcontesting] Log Periodic ?

[Mark Spencer]

Having used the smaller Create LPDA I don't necessarily disagree with your assessment of the gain, but I I have never measured mine so I can't really comment.

Subjectively the front to back ratio on mine seems quite good and of course  I set mine up for horizontal polarization.

Antother dimension to this issue is time.   I plan on spending 20 to 30 minutes per band to put up dedicated masts (typically 20 to 30 feet high to clear near by trees) and antennas for each band when I setup at a typical site.   Tear down time is a bit less.    The LPDA lets me operate on multiple bands vs spending time putting up and tearing down antennas.   By using the LPDA I can easily pickup two hours of operating time vs spending time on antenna setup and tear down during a contest.

That being said it does have limitations and to recap I left mine at home during the last contest.

73
Mark S

VE7AFZ

mark at alignedsolutions.com
604 762 4099

> On Sep 14, 2017, at 9:13 AM, Bill Olson <callbill at hotmail.com> wrote:
> 
> Hi all, Create claims the gain of the 50-1300MHz LPDA is 10-12dBi (~8-10dBd). I don't see how those numbers could possibly be accurate given the element taper and the boom length etc.. Reports of performance compared to single band Yagis seem to bear that out. I'd guess the realistic gain is more like 3-4dB over a dipole. That's like a 2 or 3 element single band Yagi.. Now admittedly you'd need 2,3,4, 5 or 6 single band Yagis to do the job since the Log Periodic does cover 6 ham bands.. If you can tolerate mediocre performance (probably really poor performance on 903/1296) but need the simplicity of a single antenna I guess this would be an option, but I sure wouldn't go that way,. Heck, it looks like the thing costs $519 too, (from DX Engineering at any rate)!! Holy smokes! The way I see it, you're paying for having broad band performance which you aren't using.. It works as well at 88MHz as it does at 144! Great for a TV antenna but who needs that on the ham bands?!
> 
> I GET the simplicity factor and agree that ANY antenna is better than no antenna, and I KNOW people are using these antennas and are happy with them, just saying my piece I guess..
> 
> 
> bill, K1DY in Maine
> 
> ________________________________
> From: VHFcontesting <vhfcontesting-bounces at contesting.com> on behalf of Zack Widup <w9sz.zack at gmail.com>
> Sent: Thursday, September 14, 2017 2:23 PM
> To: VHF Contesting Reflector
> Subject: Re: [VHFcontesting] Log Periodic ?
> 
> I think if you're close to a metropolitan area with a lot of people to
> work who are close by, the log periodic is the way to go. Some of the
> Rovers in the Chicago area I know use LPDA's. My favorite portable
> location is about 100 miles from the closest stations I work. I have
> found it's advantageous to use a separate, larger beam with more gain
> for each band.
> 
> 73, Zack W9SZ
> 
> 
>> On Thu, Sep 14, 2017 at 7:45 AM, Patrick Thomas <p-thomas at mindspring.com> wrote:
>> Like all things in contesting, I think it depends on one's goals and circumstances.  Sure, an LPDA will not perform as well as long (maybe even mid-length) yagis.  But... it also will cost less, take up less space in the vehicle, take up less space/weight on the mast, take less time to set up (assuming you start from scratch), and will only require one run of heavy coax.  Plus obviously AN antenna will outperform NO antenna!  And as others have mentioned, you can use it for a backup "any band that failed" antenna in the future, if you later graduate to a higher-performing setup.
>> 
>> Cheap surplus coax switches of good quality show up fairly often on ebay that can handle frequencies up to 1-2 GHz at a couple hundred watts, switching between 6-10 connectors, and these are easily controlled by anything from an automated arduino to a pushbutton control panel, so I would not be turned off by the need for a switch.
>> 
>> Just my thoughts on the matter.  I considered building my own LPDA as there are many good calculators out there, but ended up with a large van for a rove vehicle, which will happily swallow many large antennas.  Now if it would just run reliably....
>> 
>> Patrick
>> KB8DGC
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