The BOLPA (Band Optimised Log Periodic Array) von InnovAntenna
The BOLPA (Band Optimised Log Periodic Array) is a Log Periodic Dipole Array (LPDA) that is as far away from a traditional ‘calculator-based’ LPDA as you can get. Rather than all elements being sized and spaced to give an even performance throughout, the BOLPA have been optimised to give highest performance within the ham bands leading to exceptional performance over the whole of any covered band. With a direct 50Ohm feed point, overall F/B and forward gain is increase over generic 200Ohm LPDAs too as well as a marked increase in power handing ability. A total of 10 elements on a 7.7m boom. Designer Justin Johnson G0KSC overviews the BOLPA Design in the ARRL Antenna Book.
The BOLPA-10 is the flag-ship model. It is produced by means of placing 3 monoband LPDAs (20/15/10) on the same boom along with a dedicated 17m element and then the spacing between each 3 element cell adjusted to enhance performance for each band. 17m is not compromised as it still uses the last of the 3element 20m elements and first of the 15m element to achieve its performance. Not only does the BOLPA-10 cover all of 20, 17 and 15m band fully without an ATU being needed, performance and SWR remains flat from 24MHz through to 30MHz too. The BOLPA-10 is fast becoming the choice of Europe’s ‘home-station’ Big Guns.
The BOLPA-4 is brand new and gives the advantages of the BOLPA to those with reduced space. The BOLPA-4 have a boom length of 5.5m and just 4 elements yet covers the 15m band fully and then covers 24.8MHz to 30MHz flat and without gaps. Like all BOLPAs the BOLPA-4 has a direct 50Ohm feed point impedance and is super HD with element tapers allowing for wind handling well over 160KPH.
A picture of the BOLPA-4 and antenna patterns at different frequencies: ( Slide the pictures further for all frequencies ;) )
The BOLPA-3 is provided in a much smaller package so is suitable to light weight masts and towers. The BOLPA-3 sits on a 3.5m boom and covers 24.8MHz to 30MHz without gaps so really is an excellent choice for those who want to have something for the upper HF bands for the new solar peak.
A picture of the BOLPA-3 and antenna patterns at different frequencies: ( Slide the pictures further for all frequencies ;) )
The BOLPA-2 is a very compact version of this antenna with just a 2.4m boom and 2 elements, the BOLPA-2 covers all of the 11m and 10m bands. SWR is a little high on 12m but with a ‘nudge’ from an ATU the BOLPA-2 works well on 12m and still delivers round 4.5dBi on that band. When tower space is limited but 10m is a must, the BOLPA-2 is the one to choose.
A picture of the BOLPA-2 and antenna patterns at different frequencies: ( Slide the pictures further for all frequencies ;) )
If you have any questions about the BOLPA or InnovAntenna, please feel free to contact us!
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