On Performance of Hidden Car Roof Antennas

Abstract

Hidden antenna solutions for car roofs are of current interest to car manufacturers, to avoid having larger shark-fin based antenna systems to support growing number of wireless services. However, there are only a few studies in the literature on the integration of hidden antennas, particularly in relation to realistic roofs and propagation channels. This paper investigates the performance impact of hiding car roof-top antennas in roof cavities for an outdoor channel defined by an angular power spectrum. Different 700 MHz antenna concepts and roof cavity locations are considered for an idealized flat roof as well as a real curved roof. The results reveal that hiding antennas in cavities result in a minor mean effective gain (MEG) penalty of up to 1 dB, for a flat rectangular car roof. However, a realistic roof curvature can largely offset the MEG loss. Moreover, different monopole-based antenna concepts can provide MEG variations of up to nearly 3 dB, indicating that significant performance gain can be achieved through an optimized design.

Quad-Element LTE Hidden Car Roof Antenna System

“…For the single-element antenna design, the 6 dB impedance bandwidth should cover LTE Band 13 (746-787 MHz), and it should fit into a typical car roof cavity with slanting walls (see Fig. 1(a) and 1(c)) [6], [9]. Furthermore, since LTE signals are exchanged with elevated base station antennas, the main directions of arrival (and departure) of the radio signals at the car roof tend to be uniformly spread in azimuth but cluster around  = 60º-90º in elevation.…”

“…There have been recent investigations on the design and performance of hidden vehicular antennas in roof cavities, e.g., [5]- [9]. However, they focus on single-element antennas and only a few papers consider a low LTE band (e.g., Band 13, 746-787 MHz) [7]- [9].…”

“…There have been recent investigations on the design and performance of hidden vehicular antennas in roof cavities, e.g., [5]- [9]. However, they focus on single-element antennas and only a few papers consider a low LTE band (e.g., Band 13, 746-787 MHz) [7]- [9]. At the lower end of common LTE bands, Band 13 poses a great challenge when it comes to designing a physically compact antenna that can fit into the roof cavity.…”

Automotive Antenna Roof for Cooperative Connected Driving

“…The first antenna module was built at the front end of the car roof. A regular chassis antenna cavity with four walls at this position was considered in simulations in [35]. Instead of this straightforward approach, the investigated antenna module used the roof curvature as an advantage.…”