Example Report 7: Minature LPDA 2 - 11 GHz
Description: This PCB antenna is designed and sold by Kent Britain WA5VJB, and can be found on his website. On eBay, they were a mere $6.00 at the time of this testing. It is a Log Periodic Dipole Array (LPDA) antenna designed for the 2 - 11 GHz range, implemented on a FR4 PCB . This RTCE report covers 251 frequency points (700 MHz - 18.5 GHz) with 1 degree resolution 2D polar-cut gain results. LPDA antennas are not the same as Yagi antennas, and are a compromise arrangement of shrinking elements designed to cover a broad range of frequencies. The designer tries to minimize the number of elements to save space, without leaving "gaps" in the operating range which occur at frequencies in between the operating lengths of the actual elements.
Analysis: The antenna had a peak forward gain of +5.8 dBi at 6 GHz. See the graph in the results spreadsheet for gain vs. frequency over the entire operating range (and well outside of this range!). The swept front-to-back ratio graph always shows a lot of peaks and valleys, and varies considerably with frequency because of the width and depth of nulls that form exactly along the -Z reverse axis. When smoothed, F/B rises from around 2dB at 2 GHz, to 8 dB at 3 GHz, to 20 dB at 6 GHz, remaining above 20 dB to above 13.4 GHz.
As always, since all data is recorded in spread sheet format, additional plots and post analysis is always possible.
All pictures are "click to enlarge".
| Closeup photo of the antenna under test. |
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| Please click on the icon to the right to download the Excel data for this test report. |
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| 2D polar plot (non-standard 1 degree resolution) at 7.3 GHz. This is a frequency of interest because the antenna displays peak F/B ratio. |
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| A very wide band froward gain plot, from 700 MHz to 18.5 GHz |
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| A setup photo showing the mounting arrangement |
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| An additional setup photo showing the antenna under test with a paper diagram illustrating the coordinate system axes |
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| An additional setup photo showing the antenna under test at a distance |
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Service Summary
Antenna Gain Patterns
EIRP, TRP, Efficiency
RF Design and Debug
RSE and Harmonics
Failure Mitigation
GSM/CDMA Cellular
