Cushcraft 5 element 432 MHz Yagi antenna. Purchased for $5 at the September 2013 Sacramento Valley Hamfest. The CushCraft antenna elements have been mounted on a new rigid aluminum boom.
70 cm 5 element Yagi antenna dimensions. The driven element (with pink center) is 1.2 cm diameter and the other elements are 0.4 cm diameter.
24 NOV 2013 - This weekend I did some preliminary testing on the 5 element 432 MHz Yagi antenna.
The antenna's gamma match capacitor is a piece of coaxial cable center and dielectric inside an aluminum tube. The WaveNode indicates 2:1 minimum SWR at 432 MHz with the shorting clip closest to the feed point. I question the accuracy of the SWR reading taken with a calibrated WaveNode sensor through an 8 foot length of RG-8A/U and plan to measure it with the miniVNA when its Extender accessory arrives.
70 cm 5 element Yagi 3-dimensional radiation pattern (with 4nec2)
The Yagi's NEC model over my metal roof estimates maximum gain of 16 dBi at 5° elevation angle.
The Yagi's NEC model over my metal roof estimates an effective gain of 16 dBi and 3 dB beam width of 50°.
The Radio Mobile Online application shows the expected coverage with a beam heading of 230° may reach Santa Rosa and the San Jose areas.
The yellow areas represent signal to noise ratio above -20 dB and the orange areas are -20 to -30 dB.
The lithium battery powered miniVNA and its Extender attaches directly at the 70cm Yagi antenna feedpoint to measure the antenna parameters. The VNA-J software program running on my ASUS netbook controls the miniVNA via Bluetooth. The Extender accessory raises the miniVNA frequency range up to 1.5 GHz.
Closeup view of the miniVNA Extender attached to the 70cm Yagi antenna feedpoint. The miniVNA extender accessory allows measurements up to 1.5 GHz.
70 cm Yagi antenna SWR and Return Loss measured with miniVNA and extender. 1.01:1 minimum SWR at 431.8 MHz with less than 1.7:1 from 427 to 437 MHz.
70 cm Yagi antenna Resistance and Reactance measured with miniVNA and extender. 49 ohms non-reactive impedance at 431.6 MHz.
These new 35 foot lengths of Times Microwave LMR-400 cable will replace the three 40 year old Belden 8214 RG-8/U cables on my VHF-UHF equipment. At 144 MHz each LMR-400 cable yields 0.49 dB measured attenuation vs. 1.6 dB with the Belden cables, a significant improvement for the VHF/UHF WSPR propagation study. The attenuation at 432 MHz is 1.0 dB.
The coaxial cables pass through the exterior wall via lengths of 3/4 inch schedule 40 PVC conduit with flush bushings on each end.
Rubber grommets seal the air space around the cables.
14 DEC 2013 - Today I replaced the old Belden 8214 coaxial cable with new Times Microwave LMR-400 cable on the Arrow OSJ 146/440 J-pole and stacked halo antennas. The halo antennas were rotated to the east side of the mast and the new 5 element 432 MHz Yagi mounted at 230° bearing.
14 DEC 2013 - View of the Arrow OSJ 146/440 J-pole (at 20 feet), the top 2 meter halo antenna of the stacked pair (at 18 feet), and the 5 element 432 MHz Yagi antenna (at 17 feet).
14 DEC 2013 - Close up view of the top 2 meter halo antenna of the stacked pair and the 5 element 432 MHz Yagi antenna
14 DEC 2013 - View from below: the 144 MHz stacked halo antennas face east, the 5 element 432 MHz Yagi antenna facing 230°. and the Arrow OSJ 146/440 J-pole at the top.
The Radio Mobile Online application shows the expected 432 MHz WSPR coverage with 50 watts transmitter power and the 5 element Yagi antenna with a heading of 230°. The red lines indicate the central main beam heading and the 50° 3 dB beamwidth.
18 DEC 2013 - 432 MHz WSPR decodes were achieved to Livermore, Tracy and over the Pacific Coast ranges to Santa Rosa, CA with 50 watts and 5 element Yagi antenna at 17 feet at KP4MD station near Sacramento, California.
Elevation profile KP4MD (Citrus Heights) - N6GN (Santa Rosa) path
Elevation profile KP4MD (Citrus Heights) - N6KOG (Tracy) path
Elevation profile KP4MD (Citrus Heights) - KD6RF (Livermore) path
Path from N6SKM in Pleasanton, CA to KP4MD in Citrus Heights, CA. 76.6 mi distance with intervening 2428' elevation Diablo Ridge.
11 DEC 2013 - Received WSPR signals on 432.3 MHz with a frequency correction at 15:14 UTC. These visible traces did not decode.
12 DEC 2013 - 432 MHz WSPR spots received at station KP4MD in Citrus Heights, CA. The signal from N6KOG in Tracy, CA was spotted at 0602 UTC and the N6GN signal from Santa Rosa, CA is seen with superimposed aircraft scatter at 0608 UTC.