Evaluation of log periodic, 0.8-2.7 GHz

Created: Mar. 2023

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This log periodic aerial is advertised for cellular reception in the 0.8-0.96 GHz and 1.7-2.7 GHz bands but I saw no reason why the log periodic would not have continuous reception over 0.8-2.7 GHz. I desired a continuous coverage because my intended use is locating RF interference and measuring shielding effective. Incidentally, it also covers the ham bands 1296 MHz (23 cm) & 2420 MHz (13 cm). 

Unlike most log periodic sold online, this one is NOT a PCB, but a conventional metal (steel?) construction. It is enclosed by a radome made of ABS plastic (fig. 1). Connection is made thru a 20 cm long pigtail with an N female. Peeking inside the radome reveals an 8 element aerial.

The advertised performances are:

800-960 MHz / 1710-2700 MHz

Gain: 9dBi/13dBi

Pmax = 50W

The aerial can be attached to a pole / mast via a mounting bracket with a U-bolt. The The U-bolt's position can be adjusted for down-tilting the aerial. Unfortunately, using the supplied bracket, only vertical polarization is possible.

I measured the return loss on a nanoVna v2. The minimum freq does go a little lower than advertised; i.e. the return loss is still acceptable at ~660 MHz (fig. 2). The max. freq is as advertised; i.e. 2.7 GHz. There are two unexpected mismatches at 2.0 GHz and 2.25 GHz.

This post's most glaring shortcoming is that it lacks gain measurement and radiation pattern plot. I plan to measure these in the future, but I need to set up a measurement range first!