w4OP LOOP Antenna
W4OP Small Transmit/Receive Loop
Patent pending as of 06/14/2016
It seems that more and more, amateurs are facing increasingly strict HOAs. This antenna is not designed for the backpacker, but rather for the QRP amateur that is looking for a small antenna for home, backyard, portable or the park use.
The primary design goal was to offer a loop at lower cost than what is available but with better performance, high quality construction and features not found on the currently available loops.
To that end, this design has almost 100 parts, many of which require considerable machining to achieve excellent fit.
The coupling loop features a novel hybrid coupling scheme that guarantees a match of 1.2:1 or better from 60-10M when the antenna is mounted in the clear.
In addition, the coupling loop assembly easily adjusts in height to guarantee an optimal match on all bands. The height adjustment is accomplished by loosening the plastic thumb screw, adjusting the height and relocking the thumbscrew.
While height adjustment is not mandatory when changing bands, extremely low SWR can be achieved if one takes the time to adjust the coupling loop height.
The loop comes with 4 machined stabilizing feet that attach by custom locking thumb screws. A tripod option will be available in the near future, as will be 6M coverage.
The main tuning variable cap is dual gang and does not make use of the lossy grounding fingers. Rather, the 2 gangs are connected in series. A 6:1 reduction drive makes for easy tuning. On 12M and 10M, the bandspread is very wide making for even less critical adjustment.
The narrower the bandwidth for a given SWR, the more efficient the loop. Compare our 40M 2.62 and 2:1 bandwidth with our competition:
Plot of the W4OP LOOP on 60M:
Plot of the W4OP LOOP on 20M:
|Small HF Loop Specs|
|Band Coverage:||60m – 10m (6m option planned)|
|Power Handling:||15W SSB/CW, 10W Digital|
|Antenna Weight:||3 Pounds|
|Connector:||Female gold/Teflon BNC|
|Shipping Size:||18″ x 18″ x 4″|
|Hardware||Stainless Steel & Nylon|